. is one of the rare European surgeons to make authority in the USA. It is true that at the same time researcher and clinician, it managed to be essential like the international category leader of the prostheses to coating of hydroxyapatite. Because it resides at Maastricht, one cannot prevent oneself from referring to .

 

 

. : , which are you?

. : I am before any csotcina.comedic surgeon, in post with the University hospital of Maastricht. I also occupy the functions of “senior ” to the head of the csotcina.comédique research service, within the laboratory of the Biomaterials of our University.
Beyond the hip surgery, and in particular the surgery of recovery, I can thus be interested particularly in search of the techniques relating to bone regeneration and the implant fixation.


. : , which are you?

. : I am before any csotcina.comedic surgeon, in post with the University hospital of Maastricht. I also occupy the functions of “senior ” to the head of the csotcina.comédique research service, within the laboratory of the Biomaterials of our University.
Beyond the hip surgery, and in particular the surgery of recovery, I can thus be interested particularly in search of the techniques relating to bone regeneration and the implant fixation.


: You and researcher, is this is thus at the same time clinician easy to manage, in an everyday activity?

. : The combination of an activity of surgeon and scientist being described as ideal, insofar as the problems encountered by the clinician are examined (and sometimes solved) by the researcher in the most direct way.
It should be recognized that it results a considerable workload from it to reconcile these two poles of activity at the same person. I try to organize my timetable consequently, say two thirds for my work of csotcina.comedic surgeon, and the last third party for the basic research and private clinics.

. : The name of the University of is often quoted in your work…

. : The Group of Search of has a very old fame as regards work on the biomaterials, in the medical field and in dentistry. We began our collaboration with this group with beginning of the year 80, starting from their experiments on the coatings hydroxyapatite (HA) in dental implementations.
In fact if one their work axes is devoted as for us to the , it is more on the plan of the manufactoring processes of materials, while our Group of Maastricht is mainly interested in the elements of biochemical and experimental search. In this direction, Maastricht and seem completely complementary.

. : Did you begin your work on the hydroxyapatite by Universitaire tradition, or personal conviction?

. : By personal conviction. I started to interest me in search on coatings ha because I was not satisfied by the methods of implant fixation available at the time. That one speaks about cement or porous metal, one finds a significant number of disadvantages during their use, primarily because of the nonbiological character of these materials. I then acquired the conviction that the hydroxyapatite and the others compounds could have to offer much more, and this certainty was not since then contradicted
I have in fact begun the implantations from femoral stems ha since 1986. The cups ha followed at the beginning of 87. This clinical experiment made following the multiple experimental work undertaken during the last decade, which had been able to show the superiority of the coatings hydroxyapatite, compared to the other methods used previously for fixing uncemented of the implants.

. : You in Maastricht, do you feel live particularly European?

. : Yes, I feel very European, but it is undoubtedly more than one choice of individual that about a place of residence. It is true however that Maastricht, as one of the cities more in the south of the Netherlands, always maintained the very close relations with Belgium and Germany. Here nearly twenty years that I live Maastricht, and I am very happy to state me European, especially since the opening of the borders of the European Union.

. : You have thus to applaud the creation of ?

. : Not only I applauded the constitution of , but I am one of the charter members. This offers to the European surgeons at the same time a challenge and a chance to work together under better conditions. There exists in Europe a fantastic potential of scientific knowledge, perhaps higher than what one can find in the USA. But because we are usually divided by problems of language or other barriers, we let flee a great number of opportunities to the Unis or in the Asian countries. offers a single chance to us to improve our collaboration between European countries and in the long term to restore our csotcina.comedic leadership on a world level.

. : What did you think of the first meeting of the in Peak last year?

. : This first congress in Peak revealed small problems of organization, because each country sends its “delegates”, and that it results from it sometimes from the situations close to the political meetings. It is in addition necessary to reconcile the requirements of timetable and the access of the greatest number of speakers, which is by definition the quadrature of the circle in the event of “open” society. In this direction, the problem of parallel meetings on similar subjects must certainly be corrected, with a segmentation according to the poles of interest, even if it is always of and hip surgery
One can however consider that this meeting was very profitable on the scientific level, would be only because it succeeded in proving that at the European level a great number of research tasks are in hand, and that we have to learn from/to each other much

. : “” American is an entity very special and closed, think that a reconciliation with the is possible?

. : The first of the things to be made for Europeans is to link itself. It is only once this aim reached which one could consider a closer cooperation with American. Still be necessary-you he initially to speak about equal footing with the US surgeons that this is the proof of its credibility and can acquire a sufficiently strong identity.

. : In connection with North-American surgeons, you with them, how do you consider them worked much?

. : I enormously have respect for the American surgeons because of their excellent standards of quality of care. On another side, and as a main part in consequence of the implication of the FDA in the development of modern technologies, the therapeutic guidelines tend to remain primarily “preserving”. We must do everything in Europe to avoid such an administrative brake with therapeutic progress. Obviously, new technologies must be evaluated according to very strict scientific criteria to avoid any harmful side-effect. But these methods of assessment should not in no case to prove Draconian at the point to keep the patients away of significant progresses which modern medicine can offer to them.

. : The “preserving” guidelines to which you made allusion slow down the hydroxyapatite in the USA naturally, which in is in Europe?

. : You know, even if the “” currently finds a gain of popularity in the United States, and even if the coatings hydroxyapatite are still difficult access for the whole of the American surgeons for administrative reasons, it does not remain about it less than certain prostheses ha are legally authorized on the US market, in particular the stem, since the Christmas Day 90! In addition, and little by little, these types of coating start to be dissociated from different “without cement”, and all the large american companies are interested in it, including ! Japanese and the other countries of “” tend to imply in a more precise way, and I would not be astonished that these countries open in the years to come in a very fast way to technologies ha.
As regards Europe, my impression is that there exists already currently a great interest for the hydroxyapatite in all the Community countries. A great number of research tasks relating to very a large range of parameters of fixing of the prostheses was published right now, and the clinical use of the covered implants of hydroxyapatite is in increase.

. : It seems that there are several qualities of ha; if one increases the number of prostheses ha, and thus of manufacturers, T it does not have there not a risk of degradation of the results?

.: The risk of discredit of which can suffer a relatively new technique such as the ha because of the poor results of bad coatings is real, and I want of it for proof the repercussion given to the USA with some fragmentary observations published by and Hoffmann. It will never be said rather indeed that the techniques of coating hydroxyapatite must be assumed by centers of manufacture particularly broken with these methods.
One however attends the multiplication of coatings ha commercially available. In terms of clinical results, there is for the moment between them more similar observations that points of difference. Nevertheless, with regard to the tissue answer in situ, of the significant differences probably exist between the various coatings, chemical composition methods of implementation. The components of crystallinity, from purity of the hydroxyapatite, thickness, density and recovery vary in a major way from one manufacturer to another. Consequently, the speed of ostéo-affixing and the degree of degradation can vary in a major way. Which will be the consequences of these variations, we can for the moment only apprehend it partially.
In practice, a coating low thickness (up to icrons) of high density and intermediate crystallinity implemented to the rough substrate of an implant whose geometry is adapted to a transmission stresses in charge, constitutes certainly a good approach.

. : To avoid the defective coatings, would be you in favor of a monopoly of manufacture of coatings ha?

. : Not, at all. The competition between various Research centres and of manufacture of coatings ha is in oneself an excellent element of stimulation and progress. But this is true only if each one of these Centers is implied in search to improve its characteristic produced. However force is to note that unfortunately many manufacturers are satisfied to copy certain products servilely. This is not only detrimental for scientific progresses, but also tends to accredit in the spirit of the csotcina.comedic Community the idea according to which it could suffice for a prosthesis to be painted in #FFFFFF to be valid, without being concerned with parameters of coating. We must expect some serious disasters on the plan of the clinical outcomes, simply because of bad copies of coatings ha implemented to bad implants. And then indeed this irrefutable fact can generate a bad name for the hydroxyapatite.
It will never be said enough, the coating itself is not the essential component of a prosthesis. What characterizes a good implant, it is a balance successful between on the one hand a geometry adapted, including the surface quality of the substrate, and on the other hand the technically powerful implementation of a valid coating.

. : And criticisms concerning the resorption of the ha and the risk of remote osteolysis?

.: The is a physiological material prone to osteoclastic degradation just like any other mineral-bearing party of our skeleton. If this degradation occurs in a slow and controlled way, the ha could be replaced by bone while the remains of coating ha will be destroyed in a physiological and natural way by the human body: there is not matter with problems. This process depends much on quality of the coating. So indeed this coating is not good quality, a not controlled degradation can generate the remains salting out formed by harmful particles, with all the consequences which can result from it.
The remains salting out of hydroxyapatite sometimes put forward by the detractors of the hydroxyapatite, and supposed to come from a “not controlled” degradation is thus seen only for the coatings of poor quality. Thomas made into 93 in the USA a study concerning the comparative wear of polyethylene for similar metal heads coming from stems ha, cemented and with porous metal. Stems ha were recognized like inducing the weakest wear. Thus, association Ha-increase in articular wear is a myth
It is the same for “migrating” osteolyses whose no case was reported at the end of a recent clinical review published in the Books of teaching of , the radiographic results of more than 5000 stems ha established by Authors coming from different horizons. The explanation could lie in the intimate contact bone-metal permitted by the of apatite, and preventing the passage of the particles and remains between prosthesis and bone structures. As he was written in addition, the hydroxyapatite protects the bone from osteolysis due to the remains.

. : Can one speak about the hydroxyapatite like “biological cement”?

. : The hydroxyapatite could be actually regarded as biological cement as regards solidity of fixing in the short and medium term. However, this name which is placed in parallel with acrylic cement, can appear not very suitable long-term. Indeed, contrary to cement, the ha is intended to undergo a physiological degradation to be replaced by bone. A robust ostéo-integration bone-implant constitutes the finality of an implant with coating ha. Thus after having fulfilled its role, the hydroxyapatite can disappear gradually, without letting plane the risk of later potential disasters. Acrylic cement on the contrary can as for him still be likely to be degraded in the long run, without leaving of second valid line of defense.
The hydroxyapatite thus brought to the implant fixation a “biological” potentiality, not yet forwards for any of all the methods of prosthetic fixing used previously. The fixing of the prostheses with coating hydroxyapatite can be regarded as different from any other, in particular porous cement and metal. In this direction, the term of “third channel”, that we regularly used, seems me to be appropriate perfectly.

. : What is it coatings ha of knee prostheses?

. : Knees ha are forwarded under one day different. The technique of coating is worked out, although this problem can be now regarded as solved. The real difference, it is that as regards knees, success does not depend only on the capacities of fixing of the implant to the neighbouring bone, but also of a rigorous balance and an correct alignment of the mechanical axis of the lower extremity. Thus to obtain an initial mechanical stability can appear more difficult with a knee than with a hip.

. : Then can the hydroxyapatite appear reliable at a place and dubious with others?

. : Not. There do not exist specific differences between the various surfaces of implementation of the coatings ha, which it is about femoral components or of hip prosthese, or of femoral components or tibial of knee prostheses, even still of shoulder prosthese or tibio-tarsal implants the differences in results are explained by the degree of obtaining a sufficient initial mechanical stability to the interface to make it possible fixing by osseointegration to develop in a valid way. And for this reason of course exist very different conditions according to the anatomical localization.
Even if it were proven, in particular by , that a covered implant of ha and forwarded to will be able nevertheless to forward an ostéo-integration, which will be never the case of not covered implants, it is obvious that if these exceeds a critical point, this osteogenesis will not be able never to be carried out and it will be the failure. The difference between the various sites in implantation for a given coating thus does not hold with the coating itself, but with the mechanical conditions of prosthetic geometry, recipient site, and surgical procedure.

. : You speak about clinical outcomes, how to evaluate them in an objective way?

. : Certain tools are at our disposal as regards investigations, and in particular the radiography for which we developed the score MACAW, but also the osseous .
I am interested particularly in the , it is for me a tool of foreground for the scientific assessment of the arthroplasties, simply because it is likely to provide more precise information concerning the osseous answer with respect to the implant, in a period of time much shorter than the conventional methods. The period of observation of becoming implant can be thus considerably short cut, with in corollary an obvious benefit for all the parties concerned, including the patient

. : You quoted the score MACAW?

. : MACAW means “Agora ”. It is about a quantified score of radiographic evaluation of the femoral components of the uncemented prostheses, developed by the AGORA Group, which we had the occasion to publish in the Books of Teaching of devoted to the prostheses with coating hydroxyapatite, and to forward in complement at the time of a communication at the time of the last into 94. We will forward soon the slope this evaluation.
This score MACAW represents for us an significant improvement compared to the other methods of analysis of the parameters, and their quantified evaluation. Starting from a very broad data-processing basis and of a systematized confrontation of the clinical and radiographic data, we endeavoured to highlight certain parameters of potential risk, on the basis of the basic principle that certain signs of bone remodeling could potentially lead to problems, according to various degrees. Thus at the end of data-processing mixing several thousands of simulations radio-private clinics, according to a method corresponding to the calculation of risk factors of the insurance companies, we could allot an digital asset to each potential “risk factor”. The result is a simple figure from 0 to 6, of a handling corresponding to the quantified evaluation of Blackbird of and for clinical quotation. This score MACAW authorizes a radiographic of a series, at the individual or overall level, evolutionary evaluation in time. It also makes it possible to establish precise prognostic comparisons between various implants of geometry or different procedures of coating.

. : You are group chief executive AGORA, why this Group, which are the objectives?

. : Search in the field of csotcina.comedy was still here is little of time the fields of activity of a single personality. It is enough to refer to , , , Lord and others. Today the achievements of high-tech require the co-operation of all the scientific disciplines, with in corollary the need for a multidisciplinary co-operation at the same time enters and within the various disciplines. And this not only to generate sufficiently important series of number for the clinical judgment, but also to profit from an overall mechanism of “regulation in return” for each individual concerned separately. Thus the concept of groups directed towards a specific subject appears it like particularly gravitational, because it provides an ideal environment for the co-operation between clinicians, scientists, and engineers. We spoke much throughout this interview about Europe and of its scientific potential, the creation of this European group since 1990 answered this waiting
I thus could materialize the relations of very close cooperation founded since 1987 with Jean-Alain Epinette, who implied himself very precociously in this channel of the hydroxyapatite in France. Taking into account at the same time our joint conclusions concerning the promising future of the coatings hydroxyapatite as regards csotcina.comedic surgery, as well as need for clinical studies rigorous and equipped with suitable means for the study of the results, we decided Co-to found this Scientific Group AGORA. The AGORA is in fact “Apatite Arthroplasties”. We had appreciated in this name the Helene symbolic system of this gathering place of the ideas and knowledge of the Greek people, with the cradle of our civilization. Profiting from a logistic support of the Research center and Documentation of the Arthroplasties, based in , the AGORA largely could contribute to the development since then of knowledge as regards coating hydroxyapatite of joint prostheses.

. : Let us speak about the future: hydroxyapatite or other coatings ?

. : The coatings hydroxyapatite certainly do not have to disappear. However certain amendments of the elements can be planned to improve their biological potential. Thus their association with others made up or other methods of osseous stimulation is a gravitational idea. We will certainly not fail to note soon significant progresses in this direction. However, the basic principles of the of the coatings will be always of setting. An ideal coating is that which induces a robust ostéo-affixing in the shortest period of time, then disappears gradually while falling under the physiological process of bone remodeling, i.e. while being replaced by bone without leaving behind him persistent marks of its former existence. We are as of now very close to this result.

. : If one turns now towards the problems of polyethylene, friction and articular interface, that to think of the current evolutions: metal-metal, ceramics-polyethylene?

. : It is clear that joint surfaces of our prostheses represent from now on the main challenge for future progress of the prosthetic surgery. Although one can speak about promising options such as articular metal-metal, or ceramics, or the ionic bombardment of metal surfaces type the L-FIT, no element and no long-term follow-up allow reasonably, for the moment at least, to conclude in a clear way. Progress could also be under consideration for polyethylene itself, although one can consider it regrettable that these potential improvements of the existing components hardly impassions the polyethylene manufacturers, undoubtedly because it acts for them of a “marginal” market, and that they thus express little interest to invest in this type of prosthetic improvement. With my opinion however, it could be an possible option. At all events, we can only await the emergence of new technologies, perhaps ceramics on metal?

. : In do conclusion, how see you to it future of the coatings such as the hydroxyapatite?

. : The csotcina.comedic Community, everywhere in the world, is characterized by a relatively conservative approach with regard to the implant fixation. The rule is to confine itself (too much) a long time with the traditional methods of prosthetic fixing, while remaining perfectly conscious of their limitations. However, because at the same time of the increasingly marked control of the implants with coating hydroxyapatite, at the same time as of the publication of long-term excellent results of this type of implants in the columns of the independent reviews of the csotcina.comedic world, should note to us a fast progression of the hydroxyapatite to the international level.
In the long term, the negotiable instruments of this extension of the hydroxyapatite should initially make obsolete the other methods of fixing without cement, and in the second place, partially encroach on the market of the cemented prostheses. With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their elevated level of function activities
With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their high standard of functional activities, we will be able to only resort to optimal fixing that only the implants can offer.

: You and researcher, is this is thus at the same time clinician easy to manage, in an everyday activity?

. : The combination of an activity of surgeon and scientist being described as ideal, insofar as the problems encountered by the clinician are examined (and sometimes solved) by the researcher in the most direct way.
It should be recognized that it results a considerable workload from it to reconcile these two poles of activity at the same person. I try to organize my timetable consequently, say two thirds for my work of csotcina.comedic surgeon, and the last third party for the basic research and private clinics.

. : The name of the University of is often quoted in your work…

. : The Group of Search of has a very old fame as regards work on the biomaterials, in the medical field and in dentistry. We began our collaboration with this group with beginning of the year 80, starting from their experiments on the coatings hydroxyapatite (HA) in dental implementations.
In fact if one their work axes is devoted as for us to the , it is more on the plan of the manufactoring processes of materials, while our Group of Maastricht is mainly interested in the elements of biochemical and experimental search. In this direction, Maastricht and seem completely complementary.

. : Did you begin your work on the hydroxyapatite by Universitaire tradition, or personal conviction?

. : By personal conviction. I started to interest me in search on coatings ha because I was not satisfied by the methods of implant fixation available at the time. That one speaks about cement or porous metal, one finds a significant number of disadvantages during their use, primarily because of the nonbiological character of these materials. I then acquired the conviction that the hydroxyapatite and the others compounds could have to offer much more, and this certainty was not since then contradicted
I have in fact begun the implantations from femoral stems ha since 1986. The cups ha followed at the beginning of 87. This clinical experiment made following the multiple experimental work undertaken during the last decade, which had been able to show the superiority of the coatings hydroxyapatite, compared to the other methods used previously for fixing uncemented of the implants.

. : You in Maastricht, do you feel live particularly European?

. : Yes, I feel very European, but it is undoubtedly more than one choice of individual that about a place of residence. It is true however that Maastricht, as one of the cities more in the south of the Netherlands, always maintained the very close relations with Belgium and Germany. Here nearly twenty years that I live Maastricht, and I am very happy to state me European, especially since the opening of the borders of the European Union.

. : You have thus to applaud the creation of ?

. : Not only I applauded the constitution of , but I am one of the charter members. This offers to the European surgeons at the same time a challenge and a chance to work together under better conditions. There exists in Europe a fantastic potential of scientific knowledge, perhaps higher than what one can find in the USA. But because we are usually divided by problems of language or other barriers, we let flee a great number of opportunities to the Unis or in the Asian countries. offers a single chance to us to improve our collaboration between European countries and in the long term to restore our csotcina.comedic leadership on a world level.

. : What did you think of the first meeting of the in Peak last year?

. : This first congress in Peak revealed small problems of organization, because each country sends its “delegates”, and that it results from it sometimes from the situations close to the political meetings. It is in addition necessary to reconcile the requirements of timetable and the access of the greatest number of speakers, which is by definition the quadrature of the circle in the event of “open” society. In this direction, the problem of parallel meetings on similar subjects must certainly be corrected, with a segmentation according to the poles of interest, even if it is always of and hip surgery
One can however consider that this meeting was very profitable on the scientific level, would be only because it succeeded in proving that at the European level a great number of research tasks are in hand, and that we have to learn from/to each other much

. : “” American is an entity very special and closed, think that a reconciliation with the is possible?

. : The first of the things to be made for Europeans is to link itself. It is only once this aim reached which one could consider a closer cooperation with American. Still be necessary-you he initially to speak about equal footing with the US surgeons that this is the proof of its credibility and can acquire a sufficiently strong identity.

. : In connection with North-American surgeons, you with them, how do you consider them worked much?

. : I enormously have respect for the American surgeons because of their excellent standards of quality of care. On another side, and as a main part in consequence of the implication of the FDA in the development of modern technologies, the therapeutic guidelines tend to remain primarily “preserving”. We must do everything in Europe to avoid such an administrative brake with therapeutic progress. Obviously, new technologies must be evaluated according to very strict scientific criteria to avoid any harmful side-effect. But these methods of assessment should not in no case to prove Draconian at the point to keep the patients away of significant progresses which modern medicine can offer to them.

. : The “preserving” guidelines to which you made allusion slow down the hydroxyapatite in the USA naturally, which in is in Europe?

. : You know, even if the “” currently finds a gain of popularity in the United States, and even if the coatings hydroxyapatite are still difficult access for the whole of the American surgeons for administrative reasons, it does not remain about it less than certain prostheses ha are legally authorized on the US market, in particular the stem, since the Christmas Day 90! In addition, and little by little, these types of coating start to be dissociated from different “without cement”, and all the large american companies are interested in it, including ! Japanese and the other countries of “” tend to imply in a more precise way, and I would not be astonished that these countries open in the years to come in a very fast way to technologies ha.
As regards Europe, my impression is that there exists already currently a great interest for the hydroxyapatite in all the Community countries. A great number of research tasks relating to very a large range of parameters of fixing of the prostheses was published right now, and the clinical use of the covered implants of hydroxyapatite is in increase.

. : It seems that there are several qualities of ha; if one increases the number of prostheses ha, and thus of manufacturers, T it does not have there not a risk of degradation of the results?

.: The risk of discredit of which can suffer a relatively new technique such as the ha because of the poor results of bad coatings is real, and I want of it for proof the repercussion given to the USA with some fragmentary observations published by and Hoffmann. It will never be said rather indeed that the techniques of coating hydroxyapatite must be assumed by centers of manufacture particularly broken with these methods.
One however attends the multiplication of coatings ha commercially available. In terms of clinical results, there is for the moment between them more similar observations that points of difference. Nevertheless, with regard to the tissue answer in situ, of the significant differences probably exist between the various coatings, chemical composition methods of implementation. The components of crystallinity, from purity of the hydroxyapatite, thickness, density and recovery vary in a major way from one manufacturer to another. Consequently, the speed of ostéo-affixing and the degree of degradation can vary in a major way. Which will be the consequences of these variations, we can for the moment only apprehend it partially.
In practice, a coating low thickness (up to icrons) of high density and intermediate crystallinity implemented to the rough substrate of an implant whose geometry is adapted to a transmission stresses in charge, constitutes certainly a good approach.

. : To avoid the defective coatings, would be you in favor of a monopoly of manufacture of coatings ha?

. : Not, at all. The competition between various Research centres and of manufacture of coatings ha is in oneself an excellent element of stimulation and progress. But this is true only if each one of these Centers is implied in search to improve its characteristic produced. However force is to note that unfortunately many manufacturers are satisfied to copy certain products servilely. This is not only detrimental for scientific progresses, but also tends to accredit in the spirit of the csotcina.comedic Community the idea according to which it could suffice for a prosthesis to be painted in #FFFFFF to be valid, without being concerned with parameters of coating. We must expect some serious disasters on the plan of the clinical outcomes, simply because of bad copies of coatings ha implemented to bad implants. And then indeed this irrefutable fact can generate a bad name for the hydroxyapatite.
It will never be said enough, the coating itself is not the essential component of a prosthesis. What characterizes a good implant, it is a balance successful between on the one hand a geometry adapted, including the surface quality of the substrate, and on the other hand the technically powerful implementation of a valid coating.

. : And criticisms concerning the resorption of the ha and the risk of remote osteolysis?

.: The is a physiological material prone to osteoclastic degradation just like any other mineral-bearing party of our skeleton. If this degradation occurs in a slow and controlled way, the ha could be replaced by bone while the remains of coating ha will be destroyed in a physiological and natural way by the human body: there is not matter with problems. This process depends much on quality of the coating. So indeed this coating is not good quality, a not controlled degradation can generate the remains salting out formed by harmful particles, with all the consequences which can result from it.
The remains salting out of hydroxyapatite sometimes put forward by the detractors of the hydroxyapatite, and supposed to come from a “not controlled” degradation is thus seen only for the coatings of poor quality. Thomas made into 93 in the USA a study concerning the comparative wear of polyethylene for similar metal heads coming from stems ha, cemented and with porous metal. Stems ha were recognized like inducing the weakest wear. Thus, association Ha-increase in articular wear is a myth
It is the same for “migrating” osteolyses whose no case was reported at the end of a recent clinical review published in the Books of teaching of , the radiographic results of more than 5000 stems ha established by Authors coming from different horizons. The explanation could lie in the intimate contact bone-metal permitted by the of apatite, and preventing the passage of the particles and remains between prosthesis and bone structures. As he was written in addition, the hydroxyapatite protects the bone from osteolysis due to the remains.

. : Can one speak about the hydroxyapatite like “biological cement”?

. : The hydroxyapatite could be actually regarded as biological cement as regards solidity of fixing in the short and medium term. However, this name which is placed in parallel with acrylic cement, can appear not very suitable long-term. Indeed, contrary to cement, the ha is intended to undergo a physiological degradation to be replaced by bone. A robust ostéo-integration bone-implant constitutes the finality of an implant with coating ha. Thus after having fulfilled its role, the hydroxyapatite can disappear gradually, without letting plane the risk of later potential disasters. Acrylic cement on the contrary can as for him still be likely to be degraded in the long run, without leaving of second valid line of defense.
The hydroxyapatite thus brought to the implant fixation a “biological” potentiality, not yet forwards for any of all the methods of prosthetic fixing used previously. The fixing of the prostheses with coating hydroxyapatite can be regarded as different from any other, in particular porous cement and metal. In this direction, the term of “third channel”, that we regularly used, seems me to be appropriate perfectly.

. : What is it coatings ha of knee prostheses?

. : Knees ha are forwarded under one day different. The technique of coating is worked out, although this problem can be now regarded as solved. The real difference, it is that as regards knees, success does not depend only on the capacities of fixing of the implant to the neighbouring bone, but also of a rigorous balance and an correct alignment of the mechanical axis of the lower extremity. Thus to obtain an initial mechanical stability can appear more difficult with a knee than with a hip.

. : Then can the hydroxyapatite appear reliable at a place and dubious with others?

. : Not. There do not exist specific differences between the various surfaces of implementation of the coatings ha, which it is about femoral components or of hip prosthese, or of femoral components or tibial of knee prostheses, even still of shoulder prosthese or tibio-tarsal implants the differences in results are explained by the degree of obtaining a sufficient initial mechanical stability to the interface to make it possible fixing by osseointegration to develop in a valid way. And for this reason of course exist very different conditions according to the anatomical localization.
Even if it were proven, in particular by , that a covered implant of ha and forwarded to will be able nevertheless to forward an ostéo-integration, which will be never the case of not covered implants, it is obvious that if these exceeds a critical point, this osteogenesis will not be able never to be carried out and it will be the failure. The difference between the various sites in implantation for a given coating thus does not hold with the coating itself, but with the mechanical conditions of prosthetic geometry, recipient site, and surgical procedure.

. : You speak about clinical outcomes, how to evaluate them in an objective way?

. : Certain tools are at our disposal as regards investigations, and in particular the radiography for which we developed the score MACAW, but also the osseous .
I am interested particularly in the , it is for me a tool of foreground for the scientific assessment of the arthroplasties, simply because it is likely to provide more precise information concerning the osseous answer with respect to the implant, in a period of time much shorter than the conventional methods. The period of observation of becoming implant can be thus considerably short cut, with in corollary an obvious benefit for all the parties concerned, including the patient

. : You quoted the score MACAW?

. : MACAW means “Agora ”. It is about a quantified score of radiographic evaluation of the femoral components of the uncemented prostheses, developed by the AGORA Group, which we had the occasion to publish in the Books of Teaching of devoted to the prostheses with coating hydroxyapatite, and to forward in complement at the time of a communication at the time of the last into 94. We will forward soon the slope this evaluation.
This score MACAW represents for us an significant improvement compared to the other methods of analysis of the parameters, and their quantified evaluation. Starting from a very broad data-processing basis and of a systematized confrontation of the clinical and radiographic data, we endeavoured to highlight certain parameters of potential risk, on the basis of the basic principle that certain signs of bone remodeling could potentially lead to problems, according to various degrees. Thus at the end of data-processing mixing several thousands of simulations radio-private clinics, according to a method corresponding to the calculation of risk factors of the insurance companies, we could allot an digital asset to each potential “risk factor”. The result is a simple figure from 0 to 6, of a handling corresponding to the quantified evaluation of Blackbird of and for clinical quotation. This score MACAW authorizes a radiographic of a series, at the individual or overall level, evolutionary evaluation in time. It also makes it possible to establish precise prognostic comparisons between various implants of geometry or different procedures of coating.

. : You are group chief executive AGORA, why this Group, which are the objectives?

. : Search in the field of csotcina.comedy was still here is little of time the fields of activity of a single personality. It is enough to refer to , , , Lord and others. Today the achievements of high-tech require the co-operation of all the scientific disciplines, with in corollary the need for a multidisciplinary co-operation at the same time enters and within the various disciplines. And this not only to generate sufficiently important series of number for the clinical judgment, but also to profit from an overall mechanism of “regulation in return” for each individual concerned separately. Thus the concept of groups directed towards a specific subject appears it like particularly gravitational, because it provides an ideal environment for the co-operation between clinicians, scientists, and engineers. We spoke much throughout this interview about Europe and of its scientific potential, the creation of this European group since 1990 answered this waiting
I thus could materialize the relations of very close cooperation founded since 1987 with Jean-Alain Epinette, who implied himself very precociously in this channel of the hydroxyapatite in France. Taking into account at the same time our joint conclusions concerning the promising future of the coatings hydroxyapatite as regards csotcina.comedic surgery, as well as need for clinical studies rigorous and equipped with suitable means for the study of the results, we decided Co-to found this Scientific Group AGORA. The AGORA is in fact “Apatite Arthroplasties”. We had appreciated in this name the Helene symbolic system of this gathering place of the ideas and knowledge of the Greek people, with the cradle of our civilization. Profiting from a logistic support of the Research center and Documentation of the Arthroplasties, based in , the AGORA largely could contribute to the development since then of knowledge as regards coating hydroxyapatite of joint prostheses.

. : Let us speak about the future: hydroxyapatite or other coatings ?

. : The coatings hydroxyapatite certainly do not have to disappear. However certain amendments of the elements can be planned to improve their biological potential. Thus their association with others made up or other methods of osseous stimulation is a gravitational idea. We will certainly not fail to note soon significant progresses in this direction. However, the basic principles of the of the coatings will be always of setting. An ideal coating is that which induces a robust ostéo-affixing in the shortest period of time, then disappears gradually while falling under the physiological process of bone remodeling, i.e. while being replaced by bone without leaving behind him persistent marks of its former existence. We are as of now very close to this result.

. : If one turns now towards the problems of polyethylene, friction and articular interface, that to think of the current evolutions: metal-metal, ceramics-polyethylene?

. : It is clear that joint surfaces of our prostheses represent from now on the main challenge for future progress of the prosthetic surgery. Although one can speak about promising options such as articular metal-metal, or ceramics, or the ionic bombardment of metal surfaces type the L-FIT, no element and no long-term follow-up allow reasonably, for the moment at least, to conclude in a clear way. Progress could also be under consideration for polyethylene itself, although one can consider it regrettable that these potential improvements of the existing components hardly impassions the polyethylene manufacturers, undoubtedly because it acts for them of a “marginal” market, and that they thus express little interest to invest in this type of prosthetic improvement. With my opinion however, it could be an possible option. At all events, we can only await the emergence of new technologies, perhaps ceramics on metal?

. : , which are you?

. : I am before any csotcina.comedic surgeon, in post with the University hospital of Maastricht. I also occupy the functions of “senior ” to the head of the csotcina.comédique research service, within the laboratory of the Biomaterials of our University.
Beyond the hip surgery, and in particular the surgery of recovery, I can thus be interested particularly in search of the techniques relating to bone regeneration and the implant fixation.


: You and researcher, is this is thus at the same time clinician easy to manage, in an everyday activity?

. : The combination of an activity of surgeon and scientist being described as ideal, insofar as the problems encountered by the clinician are examined (and sometimes solved) by the researcher in the most direct way.
It should be recognized that it results a considerable workload from it to reconcile these two poles of activity at the same person. I try to organize my timetable consequently, say two thirds for my work of csotcina.comedic surgeon, and the last third party for the basic research and private clinics.

. : The name of the University of is often quoted in your work…

. : The Group of Search of has a very old fame as regards work on the biomaterials, in the medical field and in dentistry. We began our collaboration with this group with beginning of the year 80, starting from their experiments on the coatings hydroxyapatite (HA) in dental implementations.
In fact if one their work axes is devoted as for us to the , it is more on the plan of the manufactoring processes of materials, while our Group of Maastricht is mainly interested in the elements of biochemical and experimental search. In this direction, Maastricht and seem completely complementary.

. : Did you begin your work on the hydroxyapatite by Universitaire tradition, or personal conviction?

. : By personal conviction. I started to interest me in search on coatings ha because I was not satisfied by the methods of implant fixation available at the time. That one speaks about cement or porous metal, one finds a significant number of disadvantages during their use, primarily because of the nonbiological character of these materials. I then acquired the conviction that the hydroxyapatite and the others compounds could have to offer much more, and this certainty was not since then contradicted
I have in fact begun the implantations from femoral stems ha since 1986. The cups ha followed at the beginning of 87. This clinical experiment made following the multiple experimental work undertaken during the last decade, which had been able to show the superiority of the coatings hydroxyapatite, compared to the other methods used previously for fixing uncemented of the implants.

. : You in Maastricht, do you feel live particularly European?

. : Yes, I feel very European, but it is undoubtedly more than one choice of individual that about a place of residence. It is true however that Maastricht, as one of the cities more in the south of the Netherlands, always maintained the very close relations with Belgium and Germany. Here nearly twenty years that I live Maastricht, and I am very happy to state me European, especially since the opening of the borders of the European Union.

. : You have thus to applaud the creation of ?

. : Not only I applauded the constitution of , but I am one of the charter members. This offers to the European surgeons at the same time a challenge and a chance to work together under better conditions. There exists in Europe a fantastic potential of scientific knowledge, perhaps higher than what one can find in the USA. But because we are usually divided by problems of language or other barriers, we let flee a great number of opportunities to the Unis or in the Asian countries. offers a single chance to us to improve our collaboration between European countries and in the long term to restore our csotcina.comedic leadership on a world level.

. : What did you think of the first meeting of the in Peak last year?

. : This first congress in Peak revealed small problems of organization, because each country sends its “delegates”, and that it results from it sometimes from the situations close to the political meetings. It is in addition necessary to reconcile the requirements of timetable and the access of the greatest number of speakers, which is by definition the quadrature of the circle in the event of “open” society. In this direction, the problem of parallel meetings on similar subjects must certainly be corrected, with a segmentation according to the poles of interest, even if it is always of and hip surgery
One can however consider that this meeting was very profitable on the scientific level, would be only because it succeeded in proving that at the European level a great number of research tasks are in hand, and that we have to learn from/to each other much

. : “” American is an entity very special and closed, think that a reconciliation with the is possible?

. : The first of the things to be made for Europeans is to link itself. It is only once this aim reached which one could consider a closer cooperation with American. Still be necessary-you he initially to speak about equal footing with the US surgeons that this is the proof of its credibility and can acquire a sufficiently strong identity.

. : In connection with North-American surgeons, you with them, how do you consider them worked much?

. : I enormously have respect for the American surgeons because of their excellent standards of quality of care. On another side, and as a main part in consequence of the implication of the FDA in the development of modern technologies, the therapeutic guidelines tend to remain primarily “preserving”. We must do everything in Europe to avoid such an administrative brake with therapeutic progress. Obviously, new technologies must be evaluated according to very strict scientific criteria to avoid any harmful side-effect. But these methods of assessment should not in no case to prove Draconian at the point to keep the patients away of significant progresses which modern medicine can offer to them.

. : The “preserving” guidelines to which you made allusion slow down the hydroxyapatite in the USA naturally, which in is in Europe?

. : You know, even if the “” currently finds a gain of popularity in the United States, and even if the coatings hydroxyapatite are still difficult access for the whole of the American surgeons for administrative reasons, it does not remain about it less than certain prostheses ha are legally authorized on the US market, in particular the stem, since the Christmas Day 90! In addition, and little by little, these types of coating start to be dissociated from different “without cement”, and all the large american companies are interested in it, including ! Japanese and the other countries of “” tend to imply in a more precise way, and I would not be astonished that these countries open in the years to come in a very fast way to technologies ha.
As regards Europe, my impression is that there exists already currently a great interest for the hydroxyapatite in all the Community countries. A great number of research tasks relating to very a large range of parameters of fixing of the prostheses was published right now, and the clinical use of the covered implants of hydroxyapatite is in increase.

. : It seems that there are several qualities of ha; if one increases the number of prostheses ha, and thus of manufacturers, T it does not have there not a risk of degradation of the results?

.: The risk of discredit of which can suffer a relatively new technique such as the ha because of the poor results of bad coatings is real, and I want of it for proof the repercussion given to the USA with some fragmentary observations published by and Hoffmann. It will never be said rather indeed that the techniques of coating hydroxyapatite must be assumed by centers of manufacture particularly broken with these methods.
One however attends the multiplication of coatings ha commercially available. In terms of clinical results, there is for the moment between them more similar observations that points of difference. Nevertheless, with regard to the tissue answer in situ, of the significant differences probably exist between the various coatings, chemical composition methods of implementation. The components of crystallinity, from purity of the hydroxyapatite, thickness, density and recovery vary in a major way from one manufacturer to another. Consequently, the speed of ostéo-affixing and the degree of degradation can vary in a major way. Which will be the consequences of these variations, we can for the moment only apprehend it partially.
In practice, a coating low thickness (up to icrons) of high density and intermediate crystallinity implemented to the rough substrate of an implant whose geometry is adapted to a transmission stresses in charge, constitutes certainly a good approach.

. : To avoid the defective coatings, would be you in favor of a monopoly of manufacture of coatings ha?

. : Not, at all. The competition between various Research centres and of manufacture of coatings ha is in oneself an excellent element of stimulation and progress. But this is true only if each one of these Centers is implied in search to improve its characteristic produced. However force is to note that unfortunately many manufacturers are satisfied to copy certain products servilely. This is not only detrimental for scientific progresses, but also tends to accredit in the spirit of the csotcina.comedic Community the idea according to which it could suffice for a prosthesis to be painted in #FFFFFF to be valid, without being concerned with parameters of coating. We must expect some serious disasters on the plan of the clinical outcomes, simply because of bad copies of coatings ha implemented to bad implants. And then indeed this irrefutable fact can generate a bad name for the hydroxyapatite.
It will never be said enough, the coating itself is not the essential component of a prosthesis. What characterizes a good implant, it is a balance successful between on the one hand a geometry adapted, including the surface quality of the substrate, and on the other hand the technically powerful implementation of a valid coating.

. : And criticisms concerning the resorption of the ha and the risk of remote osteolysis?

.: The is a physiological material prone to osteoclastic degradation just like any other mineral-bearing party of our skeleton. If this degradation occurs in a slow and controlled way, the ha could be replaced by bone while the remains of coating ha will be destroyed in a physiological and natural way by the human body: there is not matter with problems. This process depends much on quality of the coating. So indeed this coating is not good quality, a not controlled degradation can generate the remains salting out formed by harmful particles, with all the consequences which can result from it.
The remains salting out of hydroxyapatite sometimes put forward by the detractors of the hydroxyapatite, and supposed to come from a “not controlled” degradation is thus seen only for the coatings of poor quality. Thomas made into 93 in the USA a study concerning the comparative wear of polyethylene for similar metal heads coming from stems ha, cemented and with porous metal. Stems ha were recognized like inducing the weakest wear. Thus, association Ha-increase in articular wear is a myth
It is the same for “migrating” osteolyses whose no case was reported at the end of a recent clinical review published in the Books of teaching of , the radiographic results of more than 5000 stems ha established by Authors coming from different horizons. The explanation could lie in the intimate contact bone-metal permitted by the of apatite, and preventing the passage of the particles and remains between prosthesis and bone structures. As he was written in addition, the hydroxyapatite protects the bone from osteolysis due to the remains.

. : Can one speak about the hydroxyapatite like “biological cement”?

. : The hydroxyapatite could be actually regarded as biological cement as regards solidity of fixing in the short and medium term. However, this name which is placed in parallel with acrylic cement, can appear not very suitable long-term. Indeed, contrary to cement, the ha is intended to undergo a physiological degradation to be replaced by bone. A robust ostéo-integration bone-implant constitutes the finality of an implant with coating ha. Thus after having fulfilled its role, the hydroxyapatite can disappear gradually, without letting plane the risk of later potential disasters. Acrylic cement on the contrary can as for him still be likely to be degraded in the long run, without leaving of second valid line of defense.
The hydroxyapatite thus brought to the implant fixation a “biological” potentiality, not yet forwards for any of all the methods of prosthetic fixing used previously. The fixing of the prostheses with coating hydroxyapatite can be regarded as different from any other, in particular porous cement and metal. In this direction, the term of “third channel”, that we regularly used, seems me to be appropriate perfectly.

. : What is it coatings ha of knee prostheses?

. : Knees ha are forwarded under one day different. The technique of coating is worked out, although this problem can be now regarded as solved. The real difference, it is that as regards knees, success does not depend only on the capacities of fixing of the implant to the neighbouring bone, but also of a rigorous balance and an correct alignment of the mechanical axis of the lower extremity. Thus to obtain an initial mechanical stability can appear more difficult with a knee than with a hip.

. : Then can the hydroxyapatite appear reliable at a place and dubious with others?

. : Not. There do not exist specific differences between the various surfaces of implementation of the coatings ha, which it is about femoral components or of hip prosthese, or of femoral components or tibial of knee prostheses, even still of shoulder prosthese or tibio-tarsal implants the differences in results are explained by the degree of obtaining a sufficient initial mechanical stability to the interface to make it possible fixing by osseointegration to develop in a valid way. And for this reason of course exist very different conditions according to the anatomical localization.
Even if it were proven, in particular by , that a covered implant of ha and forwarded to will be able nevertheless to forward an ostéo-integration, which will be never the case of not covered implants, it is obvious that if these exceeds a critical point, this osteogenesis will not be able never to be carried out and it will be the failure. The difference between the various sites in implantation for a given coating thus does not hold with the coating itself, but with the mechanical conditions of prosthetic geometry, recipient site, and surgical procedure.

. : You speak about clinical outcomes, how to evaluate them in an objective way?

. : Certain tools are at our disposal as regards investigations, and in particular the radiography for which we developed the score MACAW, but also the osseous .
I am interested particularly in the , it is for me a tool of foreground for the scientific assessment of the arthroplasties, simply because it is likely to provide more precise information concerning the osseous answer with respect to the implant, in a period of time much shorter than the conventional methods. The period of observation of becoming implant can be thus considerably short cut, with in corollary an obvious benefit for all the parties concerned, including the patient

. : You quoted the score MACAW?

. : MACAW means “Agora ”. It is about a quantified score of radiographic evaluation of the femoral components of the uncemented prostheses, developed by the AGORA Group, which we had the occasion to publish in the Books of Teaching of devoted to the prostheses with coating hydroxyapatite, and to forward in complement at the time of a communication at the time of the last into 94. We will forward soon the slope this evaluation.
This score MACAW represents for us an significant improvement compared to the other methods of analysis of the parameters, and their quantified evaluation. Starting from a very broad data-processing basis and of a systematized confrontation of the clinical and radiographic data, we endeavoured to highlight certain parameters of potential risk, on the basis of the basic principle that certain signs of bone remodeling could potentially lead to problems, according to various degrees. Thus at the end of data-processing mixing several thousands of simulations radio-private clinics, according to a method corresponding to the calculation of risk factors of the insurance companies, we could allot an digital asset to each potential “risk factor”. The result is a simple figure from 0 to 6, of a handling corresponding to the quantified evaluation of Blackbird of and for clinical quotation. This score MACAW authorizes a radiographic of a series, at the individual or overall level, evolutionary evaluation in time. It also makes it possible to establish precise prognostic comparisons between various implants of geometry or different procedures of coating.

. : You are group chief executive AGORA, why this Group, which are the objectives?

. : Search in the field of csotcina.comedy was still here is little of time the fields of activity of a single personality. It is enough to refer to , , , Lord and others. Today the achievements of high-tech require the co-operation of all the scientific disciplines, with in corollary the need for a multidisciplinary co-operation at the same time enters and within the various disciplines. And this not only to generate sufficiently important series of number for the clinical judgment, but also to profit from an overall mechanism of “regulation in return” for each individual concerned separately. Thus the concept of groups directed towards a specific subject appears it like particularly gravitational, because it provides an ideal environment for the co-operation between clinicians, scientists, and engineers. We spoke much throughout this interview about Europe and of its scientific potential, the creation of this European group since 1990 answered this waiting
I thus could materialize the relations of very close cooperation founded since 1987 with Jean-Alain Epinette, who implied himself very precociously in this channel of the hydroxyapatite in France. Taking into account at the same time our joint conclusions concerning the promising future of the coatings hydroxyapatite as regards csotcina.comedic surgery, as well as need for clinical studies rigorous and equipped with suitable means for the study of the results, we decided Co-to found this Scientific Group AGORA. The AGORA is in fact “Apatite Arthroplasties”. We had appreciated in this name the Helene symbolic system of this gathering place of the ideas and knowledge of the Greek people, with the cradle of our civilization. Profiting from a logistic support of the Research center and Documentation of the Arthroplasties, based in , the AGORA largely could contribute to the development since then of knowledge as regards coating hydroxyapatite of joint prostheses.

. : Let us speak about the future: hydroxyapatite or other coatings ?

. : The coatings hydroxyapatite certainly do not have to disappear. However certain amendments of the elements can be planned to improve their biological potential. Thus their association with others made up or other methods of osseous stimulation is a gravitational idea. We will certainly not fail to note soon significant progresses in this direction. However, the basic principles of the of the coatings will be always of setting. An ideal coating is that which induces a robust ostéo-affixing in the shortest period of time, then disappears gradually while falling under the physiological process of bone remodeling, i.e. while being replaced by bone without leaving behind him persistent marks of its former existence. We are as of now very close to this result.

. : If one turns now towards the problems of polyethylene, friction and articular interface, that to think of the current evolutions: metal-metal, ceramics-polyethylene?

. : It is clear that joint surfaces of our prostheses represent from now on the main challenge for future progress of the prosthetic surgery. Although one can speak about promising options such as articular metal-metal, or ceramics, or the ionic bombardment of metal surfaces type the L-FIT, no element and no long-term follow-up allow reasonably, for the moment at least, to conclude in a clear way. Progress could also be under consideration for polyethylene itself, although one can consider it regrettable that these potential improvements of the existing components hardly impassions the polyethylene manufacturers, undoubtedly because it acts for them of a “marginal” market, and that they thus express little interest to invest in this type of prosthetic improvement. With my opinion however, it could be an possible option. At all events, we can only await the emergence of new technologies, perhaps ceramics on metal?

. : In do conclusion, how see you to it future of the coatings such as the hydroxyapatite?

. : The csotcina.comedic Community, everywhere in the world, is characterized by a relatively conservative approach with regard to the implant fixation. The rule is to confine itself (too much) a long time with the traditional methods of prosthetic fixing, while remaining perfectly conscious of their limitations. However, because at the same time of the increasingly marked control of the implants with coating hydroxyapatite, at the same time as of the publication of long-term excellent results of this type of implants in the columns of the independent reviews of the csotcina.comedic world, should note to us a fast progression of the hydroxyapatite to the international level.
In the long term, the negotiable instruments of this extension of the hydroxyapatite should initially make obsolete the other methods of fixing without cement, and in the second place, partially encroach on the market of the cemented prostheses. With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their elevated level of function activities
With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their high standard of functional activities, we will be able to only resort to optimal fixing that only the implants can offer.

 

. : , which are you?

. : I am before any csotcina.comedic surgeon, in post with the University hospital of Maastricht. I also occupy the functions of “senior ” to the head of the csotcina.comédique research service, within the laboratory of the Biomaterials of our University.
Beyond the hip surgery, and in particular the surgery of recovery, I can thus be interested particularly in search of the techniques relating to bone regeneration and the implant fixation.


: You and researcher, is this is thus at the same time clinician easy to manage, in an everyday activity?

. : The combination of an activity of surgeon and scientist being described as ideal, insofar as the problems encountered by the clinician are examined (and sometimes solved) by the researcher in the most direct way.
It should be recognized that it results a considerable workload from it to reconcile these two poles of activity at the same person. I try to organize my timetable consequently, say two thirds for my work of csotcina.comedic surgeon, and the last third party for the basic research and private clinics.

. : The name of the University of is often quoted in your work…

. : The Group of Search of has a very old fame as regards work on the biomaterials, in the medical field and in dentistry. We began our collaboration with this group with beginning of the year 80, starting from their experiments on the coatings hydroxyapatite (HA) in dental implementations.
In fact if one their work axes is devoted as for us to the , it is more on the plan of the manufactoring processes of materials, while our Group of Maastricht is mainly interested in the elements of biochemical and experimental search. In this direction, Maastricht and seem completely complementary.

. : Did you begin your work on the hydroxyapatite by Universitaire tradition, or personal conviction?

. : By personal conviction. I started to interest me in search on coatings ha because I was not satisfied by the methods of implant fixation available at the time. That one speaks about cement or porous metal, one finds a significant number of disadvantages during their use, primarily because of the nonbiological character of these materials. I then acquired the conviction that the hydroxyapatite and the others compounds could have to offer much more, and this certainty was not since then contradicted
I have in fact begun the implantations from femoral stems ha since 1986. The cups ha followed at the beginning of 87. This clinical experiment made following the multiple experimental work undertaken during the last decade, which had been able to show the superiority of the coatings hydroxyapatite, compared to the other methods used previously for fixing uncemented of the implants.

. : You in Maastricht, do you feel live particularly European?

. : Yes, I feel very European, but it is undoubtedly more than one choice of individual that about a place of residence. It is true however that Maastricht, as one of the cities more in the south of the Netherlands, always maintained the very close relations with Belgium and Germany. Here nearly twenty years that I live Maastricht, and I am very happy to state me European, especially since the opening of the borders of the European Union.

. : You have thus to applaud the creation of ?

. : Not only I applauded the constitution of , but I am one of the charter members. This offers to the European surgeons at the same time a challenge and a chance to work together under better conditions. There exists in Europe a fantastic potential of scientific knowledge, perhaps higher than what one can find in the USA. But because we are usually divided by problems of language or other barriers, we let flee a great number of opportunities to the Unis or in the Asian countries. offers a single chance to us to improve our collaboration between European countries and in the long term to restore our csotcina.comedic leadership on a world level.

. : What did you think of the first meeting of the in Peak last year?

. : This first congress in Peak revealed small problems of organization, because each country sends its “delegates”, and that it results from it sometimes from the situations close to the political meetings. It is in addition necessary to reconcile the requirements of timetable and the access of the greatest number of speakers, which is by definition the quadrature of the circle in the event of “open” society. In this direction, the problem of parallel meetings on similar subjects must certainly be corrected, with a segmentation according to the poles of interest, even if it is always of and hip surgery
One can however consider that this meeting was very profitable on the scientific level, would be only because it succeeded in proving that at the European level a great number of research tasks are in hand, and that we have to learn from/to each other much

. : “” American is an entity very special and closed, think that a reconciliation with the is possible?

. : The first of the things to be made for Europeans is to link itself. It is only once this aim reached which one could consider a closer cooperation with American. Still be necessary-you he initially to speak about equal footing with the US surgeons that this is the proof of its credibility and can acquire a sufficiently strong identity.

. : In connection with North-American surgeons, you with them, how do you consider them worked much?

. : I enormously have respect for the American surgeons because of their excellent standards of quality of care. On another side, and as a main part in consequence of the implication of the FDA in the development of modern technologies, the therapeutic guidelines tend to remain primarily “preserving”. We must do everything in Europe to avoid such an administrative brake with therapeutic progress. Obviously, new technologies must be evaluated according to very strict scientific criteria to avoid any harmful side-effect. But these methods of assessment should not in no case to prove Draconian at the point to keep the patients away of significant progresses which modern medicine can offer to them.

. : The “preserving” guidelines to which you made allusion slow down the hydroxyapatite in the USA naturally, which in is in Europe?

. : You know, even if the “” currently finds a gain of popularity in the United States, and even if the coatings hydroxyapatite are still difficult access for the whole of the American surgeons for administrative reasons, it does not remain about it less than certain prostheses ha are legally authorized on the US market, in particular the stem, since the Christmas Day 90! In addition, and little by little, these types of coating start to be dissociated from different “without cement”, and all the large american companies are interested in it, including ! Japanese and the other countries of “” tend to imply in a more precise way, and I would not be astonished that these countries open in the years to come in a very fast way to technologies ha.
As regards Europe, my impression is that there exists already currently a great interest for the hydroxyapatite in all the Community countries. A great number of research tasks relating to very a large range of parameters of fixing of the prostheses was published right now, and the clinical use of the covered implants of hydroxyapatite is in increase.

. : It seems that there are several qualities of ha; if one increases the number of prostheses ha, and thus of manufacturers, T it does not have there not a risk of degradation of the results?

.: The risk of discredit of which can suffer a relatively new technique such as the ha because of the poor results of bad coatings is real, and I want of it for proof the repercussion given to the USA with some fragmentary observations published by and Hoffmann. It will never be said rather indeed that the techniques of coating hydroxyapatite must be assumed by centers of manufacture particularly broken with these methods.
One however attends the multiplication of coatings ha commercially available. In terms of clinical results, there is for the moment between them more similar observations that points of difference. Nevertheless, with regard to the tissue answer in situ, of the significant differences probably exist between the various coatings, chemical composition methods of implementation. The components of crystallinity, from purity of the hydroxyapatite, thickness, density and recovery vary in a major way from one manufacturer to another. Consequently, the speed of ostéo-affixing and the degree of degradation can vary in a major way. Which will be the consequences of these variations, we can for the moment only apprehend it partially.
In practice, a coating low thickness (up to icrons) of high density and intermediate crystallinity implemented to the rough substrate of an implant whose geometry is adapted to a transmission stresses in charge, constitutes certainly a good approach.

. : To avoid the defective coatings, would be you in favor of a monopoly of manufacture of coatings ha?

. : Not, at all. The competition between various Research centres and of manufacture of coatings ha is in oneself an excellent element of stimulation and progress. But this is true only if each one of these Centers is implied in search to improve its characteristic produced. However force is to note that unfortunately many manufacturers are satisfied to copy certain products servilely. This is not only detrimental for scientific progresses, but also tends to accredit in the spirit of the csotcina.comedic Community the idea according to which it could suffice for a prosthesis to be painted in #FFFFFF to be valid, without being concerned with parameters of coating. We must expect some serious disasters on the plan of the clinical outcomes, simply because of bad copies of coatings ha implemented to bad implants. And then indeed this irrefutable fact can generate a bad name for the hydroxyapatite.
It will never be said enough, the coating itself is not the essential component of a prosthesis. What characterizes a good implant, it is a balance successful between on the one hand a geometry adapted, including the surface quality of the substrate, and on the other hand the technically powerful implementation of a valid coating.

. : And criticisms concerning the resorption of the ha and the risk of remote osteolysis?

.: The is a physiological material prone to osteoclastic degradation just like any other mineral-bearing party of our skeleton. If this degradation occurs in a slow and controlled way, the ha could be replaced by bone while the remains of coating ha will be destroyed in a physiological and natural way by the human body: there is not matter with problems. This process depends much on quality of the coating. So indeed this coating is not good quality, a not controlled degradation can generate the remains salting out formed by harmful particles, with all the consequences which can result from it.
The remains salting out of hydroxyapatite sometimes put forward by the detractors of the hydroxyapatite, and supposed to come from a “not controlled” degradation is thus seen only for the coatings of poor quality. Thomas made into 93 in the USA a study concerning the comparative wear of polyethylene for similar metal heads coming from stems ha, cemented and with porous metal. Stems ha were recognized like inducing the weakest wear. Thus, association Ha-increase in articular wear is a myth
It is the same for “migrating” osteolyses whose no case was reported at the end of a recent clinical review published in the Books of teaching of , the radiographic results of more than 5000 stems ha established by Authors coming from different horizons. The explanation could lie in the intimate contact bone-metal permitted by the of apatite, and preventing the passage of the particles and remains between prosthesis and bone structures. As he was written in addition, the hydroxyapatite protects the bone from osteolysis due to the remains.

. : Can one speak about the hydroxyapatite like “biological cement”?

. : The hydroxyapatite could be actually regarded as biological cement as regards solidity of fixing in the short and medium term. However, this name which is placed in parallel with acrylic cement, can appear not very suitable long-term. Indeed, contrary to cement, the ha is intended to undergo a physiological degradation to be replaced by bone. A robust ostéo-integration bone-implant constitutes the finality of an implant with coating ha. Thus after having fulfilled its role, the hydroxyapatite can disappear gradually, without letting plane the risk of later potential disasters. Acrylic cement on the contrary can as for him still be likely to be degraded in the long run, without leaving of second valid line of defense.
The hydroxyapatite thus brought to the implant fixation a “biological” potentiality, not yet forwards for any of all the methods of prosthetic fixing used previously. The fixing of the prostheses with coating hydroxyapatite can be regarded as different from any other, in particular porous cement and metal. In this direction, the term of “third channel”, that we regularly used, seems me to be appropriate perfectly.

. : What is it coatings ha of knee prostheses?

. : Knees ha are forwarded under one day different. The technique of coating is worked out, although this problem can be now regarded as solved. The real difference, it is that as regards knees, success does not depend only on the capacities of fixing of the implant to the neighbouring bone, but also of a rigorous balance and an correct alignment of the mechanical axis of the lower extremity. Thus to obtain an initial mechanical stability can appear more difficult with a knee than with a hip.

. : Then can the hydroxyapatite appear reliable at a place and dubious with others?

. : Not. There do not exist specific differences between the various surfaces of implementation of the coatings ha, which it is about femoral components or of hip prosthese, or of femoral components or tibial of knee prostheses, even still of shoulder prosthese or tibio-tarsal implants the differences in results are explained by the degree of obtaining a sufficient initial mechanical stability to the interface to make it possible fixing by osseointegration to develop in a valid way. And for this reason of course exist very different conditions according to the anatomical localization.
Even if it were proven, in particular by , that a covered implant of ha and forwarded to will be able nevertheless to forward an ostéo-integration, which will be never the case of not covered implants, it is obvious that if these exceeds a critical point, this osteogenesis will not be able never to be carried out and it will be the failure. The difference between the various sites in implantation for a given coating thus does not hold with the coating itself, but with the mechanical conditions of prosthetic geometry, recipient site, and surgical procedure.

. : You speak about clinical outcomes, how to evaluate them in an objective way?

. : Certain tools are at our disposal as regards investigations, and in particular the radiography for which we developed the score MACAW, but also the osseous .
I am interested particularly in the , it is for me a tool of foreground for the scientific assessment of the arthroplasties, simply because it is likely to provide more precise information concerning the osseous answer with respect to the implant, in a period of time much shorter than the conventional methods. The period of observation of becoming implant can be thus considerably short cut, with in corollary an obvious benefit for all the parties concerned, including the patient

. : You quoted the score MACAW?

. : MACAW means “Agora ”. It is about a quantified score of radiographic evaluation of the femoral components of the uncemented prostheses, developed by the AGORA Group, which we had the occasion to publish in the Books of Teaching of devoted to the prostheses with coating hydroxyapatite, and to forward in complement at the time of a communication at the time of the last into 94. We will forward soon the slope this evaluation.
This score MACAW represents for us an significant improvement compared to the other methods of analysis of the parameters, and their quantified evaluation. Starting from a very broad data-processing basis and of a systematized confrontation of the clinical and radiographic data, we endeavoured to highlight certain parameters of potential risk, on the basis of the basic principle that certain signs of bone remodeling could potentially lead to problems, according to various degrees. Thus at the end of data-processing mixing several thousands of simulations radio-private clinics, according to a method corresponding to the calculation of risk factors of the insurance companies, we could allot an digital asset to each potential “risk factor”. The result is a simple figure from 0 to 6, of a handling corresponding to the quantified evaluation of Blackbird of and for clinical quotation. This score MACAW authorizes a radiographic of a series, at the individual or overall level, evolutionary evaluation in time. It also makes it possible to establish precise prognostic comparisons between various implants of geometry or different procedures of coating.

. : You are group chief executive AGORA, why this Group, which are the objectives?

. : Search in the field of csotcina.comedy was still here is little of time the fields of activity of a single personality. It is enough to refer to , , , Lord and others. Today the achievements of high-tech require the co-operation of all the scientific disciplines, with in corollary the need for a multidisciplinary co-operation at the same time enters and within the various disciplines. And this not only to generate sufficiently important series of number for the clinical judgment, but also to profit from an overall mechanism of “regulation in return” for each individual concerned separately. Thus the concept of groups directed towards a specific subject appears it like particularly gravitational, because it provides an ideal environment for the co-operation between clinicians, scientists, and engineers. We spoke much throughout this interview about Europe and of its scientific potential, the creation of this European group since 1990 answered this waiting
I thus could materialize the relations of very close cooperation founded since 1987 with Jean-Alain Epinette, who implied himself very precociously in this channel of the hydroxyapatite in France. Taking into account at the same time our joint conclusions concerning the promising future of the coatings hydroxyapatite as regards csotcina.comedic surgery, as well as need for clinical studies rigorous and equipped with suitable means for the study of the results, we decided Co-to found this Scientific Group AGORA. The AGORA is in fact “Apatite Arthroplasties”. We had appreciated in this name the Helene symbolic system of this gathering place of the ideas and knowledge of the Greek people, with the cradle of our civilization. Profiting from a logistic support of the Research center and Documentation of the Arthroplasties, based in , the AGORA largely could contribute to the development since then of knowledge as regards coating hydroxyapatite of joint prostheses.

. : Let us speak about the future: hydroxyapatite or other coatings ?

. : The coatings hydroxyapatite certainly do not have to disappear. However certain amendments of the elements can be planned to improve their biological potential. Thus their association with others made up or other methods of osseous stimulation is a gravitational idea. We will certainly not fail to note soon significant progresses in this direction. However, the basic principles of the of the coatings will be always of setting. An ideal coating is that which induces a robust ostéo-affixing in the shortest period of time, then disappears gradually while falling under the physiological process of bone remodeling, i.e. while being replaced by bone without leaving behind him persistent marks of its former existence. We are as of now very close to this result.

. : If one turns now towards the problems of polyethylene, friction and articular interface, that to think of the current evolutions: metal-metal, ceramics-polyethylene?

. : It is clear that joint surfaces of our prostheses represent from now on the main challenge for future progress of the prosthetic surgery. Although one can speak about promising options such as articular metal-metal, or ceramics, or the ionic bombardment of metal surfaces type the L-FIT, no element and no long-term follow-up allow reasonably, for the moment at least, to conclude in a clear way. Progress could also be under consideration for polyethylene itself, although one can consider it regrettable that these potential improvements of the existing components hardly impassions the polyethylene manufacturers, undoubtedly because it acts for them of a “marginal” market, and that they thus express little interest to invest in this type of prosthetic improvement. With my opinion however, it could be an possible option. At all events, we can only await the emergence of new technologies, perhaps ceramics on metal?

. : In do conclusion, how see you to it future of the coatings such as the hydroxyapatite?

. : The csotcina.comedic Community, everywhere in the world, is characterized by a relatively conservative approach with regard to the implant fixation. The rule is to confine itself (too much) a long time with the traditional methods of prosthetic fixing, while remaining perfectly conscious of their limitations. However, because at the same time of the increasingly marked control of the implants with coating hydroxyapatite, at the same time as of the publication of long-term excellent results of this type of implants in the columns of the independent reviews of the csotcina.comedic world, should note to us a fast progression of the hydroxyapatite to the international level.
In the long term, the negotiable instruments of this extension of the hydroxyapatite should initially make obsolete the other methods of fixing without cement, and in the second place, partially encroach on the market of the cemented prostheses. With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their elevated level of function activities
With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their high standard of functional activities, we will be able to only resort to optimal fixing that only the implants can offer.

 

. : , which are you?

. : I am before any csotcina.comedic surgeon, in post with the University hospital of Maastricht. I also occupy the functions of “senior ” to the head of the csotcina.comédique research service, within the laboratory of the Biomaterials of our University.
Beyond the hip surgery, and in particular the surgery of recovery, I can thus be interested particularly in search of the techniques relating to bone regeneration and the implant fixation.


: You and researcher, is this is thus at the same time clinician easy to manage, in an everyday activity?

. : The combination of an activity of surgeon and scientist being described as ideal, insofar as the problems encountered by the clinician are examined (and sometimes solved) by the researcher in the most direct way.
It should be recognized that it results a considerable workload from it to reconcile these two poles of activity at the same person. I try to organize my timetable consequently, say two thirds for my work of csotcina.comedic surgeon, and the last third party for the basic research and private clinics.

. : The name of the University of is often quoted in your work…

. : The Group of Search of has a very old fame as regards work on the biomaterials, in the medical field and in dentistry. We began our collaboration with this group with beginning of the year 80, starting from their experiments on the coatings hydroxyapatite (HA) in dental implementations.
In fact if one their work axes is devoted as for us to the , it is more on the plan of the manufactoring processes of materials, while our Group of Maastricht is mainly interested in the elements of biochemical and experimental search. In this direction, Maastricht and seem completely complementary.

. : Did you begin your work on the hydroxyapatite by Universitaire tradition, or personal conviction?

. : By personal conviction. I started to interest me in search on coatings ha because I was not satisfied by the methods of implant fixation available at the time. That one speaks about cement or porous metal, one finds a significant number of disadvantages during their use, primarily because of the nonbiological character of these materials. I then acquired the conviction that the hydroxyapatite and the others compounds could have to offer much more, and this certainty was not since then contradicted
I have in fact begun the implantations from femoral stems ha since 1986. The cups ha followed at the beginning of 87. This clinical experiment made following the multiple experimental work undertaken during the last decade, which had been able to show the superiority of the coatings hydroxyapatite, compared to the other methods used previously for fixing uncemented of the implants.

. : You in Maastricht, do you feel live particularly European?

. : Yes, I feel very European, but it is undoubtedly more than one choice of individual that about a place of residence. It is true however that Maastricht, as one of the cities more in the south of the Netherlands, always maintained the very close relations with Belgium and Germany. Here nearly twenty years that I live Maastricht, and I am very happy to state me European, especially since the opening of the borders of the European Union.

. : You have thus to applaud the creation of ?

. : Not only I applauded the constitution of , but I am one of the charter members. This offers to the European surgeons at the same time a challenge and a chance to work together under better conditions. There exists in Europe a fantastic potential of scientific knowledge, perhaps higher than what one can find in the USA. But because we are usually divided by problems of language or other barriers, we let flee a great number of opportunities to the Unis or in the Asian countries. offers a single chance to us to improve our collaboration between European countries and in the long term to restore our csotcina.comedic leadership on a world level.

. : What did you think of the first meeting of the in Peak last year?

. : This first congress in Peak revealed small problems of organization, because each country sends its “delegates”, and that it results from it sometimes from the situations close to the political meetings. It is in addition necessary to reconcile the requirements of timetable and the access of the greatest number of speakers, which is by definition the quadrature of the circle in the event of “open” society. In this direction, the problem of parallel meetings on similar subjects must certainly be corrected, with a segmentation according to the poles of interest, even if it is always of and hip surgery
One can however consider that this meeting was very profitable on the scientific level, would be only because it succeeded in proving that at the European level a great number of research tasks are in hand, and that we have to learn from/to each other much

. : “” American is an entity very special and closed, think that a reconciliation with the is possible?

. : The first of the things to be made for Europeans is to link itself. It is only once this aim reached which one could consider a closer cooperation with American. Still be necessary-you he initially to speak about equal footing with the US surgeons that this is the proof of its credibility and can acquire a sufficiently strong identity.

. : In connection with North-American surgeons, you with them, how do you consider them worked much?

. : I enormously have respect for the American surgeons because of their excellent standards of quality of care. On another side, and as a main part in consequence of the implication of the FDA in the development of modern technologies, the therapeutic guidelines tend to remain primarily “preserving”. We must do everything in Europe to avoid such an administrative brake with therapeutic progress. Obviously, new technologies must be evaluated according to very strict scientific criteria to avoid any harmful side-effect. But these methods of assessment should not in no case to prove Draconian at the point to keep the patients away of significant progresses which modern medicine can offer to them.

. : The “preserving” guidelines to which you made allusion slow down the hydroxyapatite in the USA naturally, which in is in Europe?

. : You know, even if the “” currently finds a gain of popularity in the United States, and even if the coatings hydroxyapatite are still difficult access for the whole of the American surgeons for administrative reasons, it does not remain about it less than certain prostheses ha are legally authorized on the US market, in particular the stem, since the Christmas Day 90! In addition, and little by little, these types of coating start to be dissociated from different “without cement”, and all the large american companies are interested in it, including ! Japanese and the other countries of “” tend to imply in a more precise way, and I would not be astonished that these countries open in the years to come in a very fast way to technologies ha.
As regards Europe, my impression is that there exists already currently a great interest for the hydroxyapatite in all the Community countries. A great number of research tasks relating to very a large range of parameters of fixing of the prostheses was published right now, and the clinical use of the covered implants of hydroxyapatite is in increase.

. : It seems that there are several qualities of ha; if one increases the number of prostheses ha, and thus of manufacturers, T it does not have there not a risk of degradation of the results?

.: The risk of discredit of which can suffer a relatively new technique such as the ha because of the poor results of bad coatings is real, and I want of it for proof the repercussion given to the USA with some fragmentary observations published by and Hoffmann. It will never be said rather indeed that the techniques of coating hydroxyapatite must be assumed by centers of manufacture particularly broken with these methods.
One however attends the multiplication of coatings ha commercially available. In terms of clinical results, there is for the moment between them more similar observations that points of difference. Nevertheless, with regard to the tissue answer in situ, of the significant differences probably exist between the various coatings, chemical composition methods of implementation. The components of crystallinity, from purity of the hydroxyapatite, thickness, density and recovery vary in a major way from one manufacturer to another. Consequently, the speed of ostéo-affixing and the degree of degradation can vary in a major way. Which will be the consequences of these variations, we can for the moment only apprehend it partially.
In practice, a coating low thickness (up to icrons) of high density and intermediate crystallinity implemented to the rough substrate of an implant whose geometry is adapted to a transmission stresses in charge, constitutes certainly a good approach.

. : To avoid the defective coatings, would be you in favor of a monopoly of manufacture of coatings ha?

. : Not, at all. The competition between various Research centres and of manufacture of coatings ha is in oneself an excellent element of stimulation and progress. But this is true only if each one of these Centers is implied in search to improve its characteristic produced. However force is to note that unfortunately many manufacturers are satisfied to copy certain products servilely. This is not only detrimental for scientific progresses, but also tends to accredit in the spirit of the csotcina.comedic Community the idea according to which it could suffice for a prosthesis to be painted in #FFFFFF to be valid, without being concerned with parameters of coating. We must expect some serious disasters on the plan of the clinical outcomes, simply because of bad copies of coatings ha implemented to bad implants. And then indeed this irrefutable fact can generate a bad name for the hydroxyapatite.
It will never be said enough, the coating itself is not the essential component of a prosthesis. What characterizes a good implant, it is a balance successful between on the one hand a geometry adapted, including the surface quality of the substrate, and on the other hand the technically powerful implementation of a valid coating.

. : And criticisms concerning the resorption of the ha and the risk of remote osteolysis?

.: The is a physiological material prone to osteoclastic degradation just like any other mineral-bearing party of our skeleton. If this degradation occurs in a slow and controlled way, the ha could be replaced by bone while the remains of coating ha will be destroyed in a physiological and natural way by the human body: there is not matter with problems. This process depends much on quality of the coating. So indeed this coating is not good quality, a not controlled degradation can generate the remains salting out formed by harmful particles, with all the consequences which can result from it.
The remains salting out of hydroxyapatite sometimes put forward by the detractors of the hydroxyapatite, and supposed to come from a “not controlled” degradation is thus seen only for the coatings of poor quality. Thomas made into 93 in the USA a study concerning the comparative wear of polyethylene for similar metal heads coming from stems ha, cemented and with porous metal. Stems ha were recognized like inducing the weakest wear. Thus, association Ha-increase in articular wear is a myth
It is the same for “migrating” osteolyses whose no case was reported at the end of a recent clinical review published in the Books of teaching of , the radiographic results of more than 5000 stems ha established by Authors coming from different horizons. The explanation could lie in the intimate contact bone-metal permitted by the of apatite, and preventing the passage of the particles and remains between prosthesis and bone structures. As he was written in addition, the hydroxyapatite protects the bone from osteolysis due to the remains.

. : Can one speak about the hydroxyapatite like “biological cement”?

. : The hydroxyapatite could be actually regarded as biological cement as regards solidity of fixing in the short and medium term. However, this name which is placed in parallel with acrylic cement, can appear not very suitable long-term. Indeed, contrary to cement, the ha is intended to undergo a physiological degradation to be replaced by bone. A robust ostéo-integration bone-implant constitutes the finality of an implant with coating ha. Thus after having fulfilled its role, the hydroxyapatite can disappear gradually, without letting plane the risk of later potential disasters. Acrylic cement on the contrary can as for him still be likely to be degraded in the long run, without leaving of second valid line of defense.
The hydroxyapatite thus brought to the implant fixation a “biological” potentiality, not yet forwards for any of all the methods of prosthetic fixing used previously. The fixing of the prostheses with coating hydroxyapatite can be regarded as different from any other, in particular porous cement and metal. In this direction, the term of “third channel”, that we regularly used, seems me to be appropriate perfectly.

. : What is it coatings ha of knee prostheses?

. : Knees ha are forwarded under one day different. The technique of coating is worked out, although this problem can be now regarded as solved. The real difference, it is that as regards knees, success does not depend only on the capacities of fixing of the implant to the neighbouring bone, but also of a rigorous balance and an correct alignment of the mechanical axis of the lower extremity. Thus to obtain an initial mechanical stability can appear more difficult with a knee than with a hip.

. : Then can the hydroxyapatite appear reliable at a place and dubious with others?

. : Not. There do not exist specific differences between the various surfaces of implementation of the coatings ha, which it is about femoral components or of hip prosthese, or of femoral components or tibial of knee prostheses, even still of shoulder prosthese or tibio-tarsal implants the differences in results are explained by the degree of obtaining a sufficient initial mechanical stability to the interface to make it possible fixing by osseointegration to develop in a valid way. And for this reason of course exist very different conditions according to the anatomical localization.
Even if it were proven, in particular by , that a covered implant of ha and forwarded to will be able nevertheless to forward an ostéo-integration, which will be never the case of not covered implants, it is obvious that if these exceeds a critical point, this osteogenesis will not be able never to be carried out and it will be the failure. The difference between the various sites in implantation for a given coating thus does not hold with the coating itself, but with the mechanical conditions of prosthetic geometry, recipient site, and surgical procedure.

. : You speak about clinical outcomes, how to evaluate them in an objective way?

. : Certain tools are at our disposal as regards investigations, and in particular the radiography for which we developed the score MACAW, but also the osseous .
I am interested particularly in the , it is for me a tool of foreground for the scientific assessment of the arthroplasties, simply because it is likely to provide more precise information concerning the osseous answer with respect to the implant, in a period of time much shorter than the conventional methods. The period of observation of becoming implant can be thus considerably short cut, with in corollary an obvious benefit for all the parties concerned, including the patient

. : You quoted the score MACAW?

. : MACAW means “Agora ”. It is about a quantified score of radiographic evaluation of the femoral components of the uncemented prostheses, developed by the AGORA Group, which we had the occasion to publish in the Books of Teaching of devoted to the prostheses with coating hydroxyapatite, and to forward in complement at the time of a communication at the time of the last into 94. We will forward soon the slope this evaluation.
This score MACAW represents for us an significant improvement compared to the other methods of analysis of the parameters, and their quantified evaluation. Starting from a very broad data-processing basis and of a systematized confrontation of the clinical and radiographic data, we endeavoured to highlight certain parameters of potential risk, on the basis of the basic principle that certain signs of bone remodeling could potentially lead to problems, according to various degrees. Thus at the end of data-processing mixing several thousands of simulations radio-private clinics, according to a method corresponding to the calculation of risk factors of the insurance companies, we could allot an digital asset to each potential “risk factor”. The result is a simple figure from 0 to 6, of a handling corresponding to the quantified evaluation of Blackbird of and for clinical quotation. This score MACAW authorizes a radiographic of a series, at the individual or overall level, evolutionary evaluation in time. It also makes it possible to establish precise prognostic comparisons between various implants of geometry or different procedures of coating.

. : You are group chief executive AGORA, why this Group, which are the objectives?

. : Search in the field of csotcina.comedy was still here is little of time the fields of activity of a single personality. It is enough to refer to , , , Lord and others. Today the achievements of high-tech require the co-operation of all the scientific disciplines, with in corollary the need for a multidisciplinary co-operation at the same time enters and within the various disciplines. And this not only to generate sufficiently important series of number for the clinical judgment, but also to profit from an overall mechanism of “regulation in return” for each individual concerned separately. Thus the concept of groups directed towards a specific subject appears it like particularly gravitational, because it provides an ideal environment for the co-operation between clinicians, scientists, and engineers. We spoke much throughout this interview about Europe and of its scientific potential, the creation of this European group since 1990 answered this waiting
I thus could materialize the relations of very close cooperation founded since 1987 with Jean-Alain Epinette, who implied himself very precociously in this channel of the hydroxyapatite in France. Taking into account at the same time our joint conclusions concerning the promising future of the coatings hydroxyapatite as regards csotcina.comedic surgery, as well as need for clinical studies rigorous and equipped with suitable means for the study of the results, we decided Co-to found this Scientific Group AGORA. The AGORA is in fact “Apatite Arthroplasties”. We had appreciated in this name the Helene symbolic system of this gathering place of the ideas and knowledge of the Greek people, with the cradle of our civilization. Profiting from a logistic support of the Research center and Documentation of the Arthroplasties, based in , the AGORA largely could contribute to the development since then of knowledge as regards coating hydroxyapatite of joint prostheses.

. : Let us speak about the future: hydroxyapatite or other coatings ?

. : The coatings hydroxyapatite certainly do not have to disappear. However certain amendments of the elements can be planned to improve their biological potential. Thus their association with others made up or other methods of osseous stimulation is a gravitational idea. We will certainly not fail to note soon significant progresses in this direction. However, the basic principles of the of the coatings will be always of setting. An ideal coating is that which induces a robust ostéo-affixing in the shortest period of time, then disappears gradually while falling under the physiological process of bone remodeling, i.e. while being replaced by bone without leaving behind him persistent marks of its former existence. We are as of now very close to this result.

. : If one turns now towards the problems of polyethylene, friction and articular interface, that to think of the current evolutions: metal-metal, ceramics-polyethylene?

. : It is clear that joint surfaces of our prostheses represent from now on the main challenge for future progress of the prosthetic surgery. Although one can speak about promising options such as articular metal-metal, or ceramics, or the ionic bombardment of metal surfaces type the L-FIT, no element and no long-term follow-up allow reasonably, for the moment at least, to conclude in a clear way. Progress could also be under consideration for polyethylene itself, although one can consider it regrettable that these potential improvements of the existing components hardly impassions the polyethylene manufacturers, undoubtedly because it acts for them of a “marginal” market, and that they thus express little interest to invest in this type of prosthetic improvement. With my opinion however, it could be an possible option. At all events, we can only await the emergence of new technologies, perhaps ceramics on metal?

. : In do conclusion, how see you to it future of the coatings such as the hydroxyapatite?

. : The csotcina.comedic Community, everywhere in the world, is characterized by a relatively conservative approach with regard to the implant fixation. The rule is to confine itself (too much) a long time with the traditional methods of prosthetic fixing, while remaining perfectly conscious of their limitations. However, because at the same time of the increasingly marked control of the implants with coating hydroxyapatite, at the same time as of the publication of long-term excellent results of this type of implants in the columns of the independent reviews of the csotcina.comedic world, should note to us a fast progression of the hydroxyapatite to the international level.
In the long term, the negotiable instruments of this extension of the hydroxyapatite should initially make obsolete the other methods of fixing without cement, and in the second place, partially encroach on the market of the cemented prostheses. With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their elevated level of function activities
With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their high standard of functional activities, we will be able to only resort to optimal fixing that only the implants can offer.

. : , which are you?

. : I am before any csotcina.comedic surgeon, in post with the University hospital of Maastricht. I also occupy the functions of “senior ” to the head of the csotcina.comédique research service, within the laboratory of the Biomaterials of our University.
Beyond the hip surgery, and in particular the surgery of recovery, I can thus be interested particularly in search of the techniques relating to bone regeneration and the implant fixation.


: You and researcher, is this is thus at the same time clinician easy to manage, in an everyday activity?

. : The combination of an activity of surgeon and scientist being described as ideal, insofar as the problems encountered by the clinician are examined (and sometimes solved) by the researcher in the most direct way.
It should be recognized that it results a considerable workload from it to reconcile these two poles of activity at the same person. I try to organize my timetable consequently, say two thirds for my work of csotcina.comedic surgeon, and the last third party for the basic research and private clinics.

. : The name of the University of is often quoted in your work…

. : The Group of Search of has a very old fame as regards work on the biomaterials, in the medical field and in dentistry. We began our collaboration with this group with beginning of the year 80, starting from their experiments on the coatings hydroxyapatite (HA) in dental implementations.
In fact if one their work axes is devoted as for us to the , it is more on the plan of the manufactoring processes of materials, while our Group of Maastricht is mainly interested in the elements of biochemical and experimental search. In this direction, Maastricht and seem completely complementary.

. : Did you begin your work on the hydroxyapatite by Universitaire tradition, or personal conviction?

. : By personal conviction. I started to interest me in search on coatings ha because I was not satisfied by the methods of implant fixation available at the time. That one speaks about cement or porous metal, one finds a significant number of disadvantages during their use, primarily because of the nonbiological character of these materials. I then acquired the conviction that the hydroxyapatite and the others compounds could have to offer much more, and this certainty was not since then contradicted
I have in fact begun the implantations from femoral stems ha since 1986. The cups ha followed at the beginning of 87. This clinical experiment made following the multiple experimental work undertaken during the last decade, which had been able to show the superiority of the coatings hydroxyapatite, compared to the other methods used previously for fixing uncemented of the implants.

. : You in Maastricht, do you feel live particularly European?

. : Yes, I feel very European, but it is undoubtedly more than one choice of individual that about a place of residence. It is true however that Maastricht, as one of the cities more in the south of the Netherlands, always maintained the very close relations with Belgium and Germany. Here nearly twenty years that I live Maastricht, and I am very happy to state me European, especially since the opening of the borders of the European Union.

. : You have thus to applaud the creation of ?

. : Not only I applauded the constitution of , but I am one of the charter members. This offers to the European surgeons at the same time a challenge and a chance to work together under better conditions. There exists in Europe a fantastic potential of scientific knowledge, perhaps higher than what one can find in the USA. But because we are usually divided by problems of language or other barriers, we let flee a great number of opportunities to the Unis or in the Asian countries. offers a single chance to us to improve our collaboration between European countries and in the long term to restore our csotcina.comedic leadership on a world level.

. : What did you think of the first meeting of the in Peak last year?

. : This first congress in Peak revealed small problems of organization, because each country sends its “delegates”, and that it results from it sometimes from the situations close to the political meetings. It is in addition necessary to reconcile the requirements of timetable and the access of the greatest number of speakers, which is by definition the quadrature of the circle in the event of “open” society. In this direction, the problem of parallel meetings on similar subjects must certainly be corrected, with a segmentation according to the poles of interest, even if it is always of and hip surgery
One can however consider that this meeting was very profitable on the scientific level, would be only because it succeeded in proving that at the European level a great number of research tasks are in hand, and that we have to learn from/to each other much

. : “” American is an entity very special and closed, think that a reconciliation with the is possible?

. : The first of the things to be made for Europeans is to link itself. It is only once this aim reached which one could consider a closer cooperation with American. Still be necessary-you he initially to speak about equal footing with the US surgeons that this is the proof of its credibility and can acquire a sufficiently strong identity.

. : In connection with North-American surgeons, you with them, how do you consider them worked much?

. : I enormously have respect for the American surgeons because of their excellent standards of quality of care. On another side, and as a main part in consequence of the implication of the FDA in the development of modern technologies, the therapeutic guidelines tend to remain primarily “preserving”. We must do everything in Europe to avoid such an administrative brake with therapeutic progress. Obviously, new technologies must be evaluated according to very strict scientific criteria to avoid any harmful side-effect. But these methods of assessment should not in no case to prove Draconian at the point to keep the patients away of significant progresses which modern medicine can offer to them.

. : The “preserving” guidelines to which you made allusion slow down the hydroxyapatite in the USA naturally, which in is in Europe?

. : You know, even if the “” currently finds a gain of popularity in the United States, and even if the coatings hydroxyapatite are still difficult access for the whole of the American surgeons for administrative reasons, it does not remain about it less than certain prostheses ha are legally authorized on the US market, in particular the stem, since the Christmas Day 90! In addition, and little by little, these types of coating start to be dissociated from different “without cement”, and all the large american companies are interested in it, including ! Japanese and the other countries of “” tend to imply in a more precise way, and I would not be astonished that these countries open in the years to come in a very fast way to technologies ha.
As regards Europe, my impression is that there exists already currently a great interest for the hydroxyapatite in all the Community countries. A great number of research tasks relating to very a large range of parameters of fixing of the prostheses was published right now, and the clinical use of the covered implants of hydroxyapatite is in increase.

. : It seems that there are several qualities of ha; if one increases the number of prostheses ha, and thus of manufacturers, T it does not have there not a risk of degradation of the results?

.: The risk of discredit of which can suffer a relatively new technique such as the ha because of the poor results of bad coatings is real, and I want of it for proof the repercussion given to the USA with some fragmentary observations published by and Hoffmann. It will never be said rather indeed that the techniques of coating hydroxyapatite must be assumed by centers of manufacture particularly broken with these methods.
One however attends the multiplication of coatings ha commercially available. In terms of clinical results, there is for the moment between them more similar observations that points of difference. Nevertheless, with regard to the tissue answer in situ, of the significant differences probably exist between the various coatings, chemical composition methods of implementation. The components of crystallinity, from purity of the hydroxyapatite, thickness, density and recovery vary in a major way from one manufacturer to another. Consequently, the speed of ostéo-affixing and the degree of degradation can vary in a major way. Which will be the consequences of these variations, we can for the moment only apprehend it partially.
In practice, a coating low thickness (up to icrons) of high density and intermediate crystallinity implemented to the rough substrate of an implant whose geometry is adapted to a transmission stresses in charge, constitutes certainly a good approach.

. : To avoid the defective coatings, would be you in favor of a monopoly of manufacture of coatings ha?

. : Not, at all. The competition between various Research centres and of manufacture of coatings ha is in oneself an excellent element of stimulation and progress. But this is true only if each one of these Centers is implied in search to improve its characteristic produced. However force is to note that unfortunately many manufacturers are satisfied to copy certain products servilely. This is not only detrimental for scientific progresses, but also tends to accredit in the spirit of the csotcina.comedic Community the idea according to which it could suffice for a prosthesis to be painted in #FFFFFF to be valid, without being concerned with parameters of coating. We must expect some serious disasters on the plan of the clinical outcomes, simply because of bad copies of coatings ha implemented to bad implants. And then indeed this irrefutable fact can generate a bad name for the hydroxyapatite.
It will never be said enough, the coating itself is not the essential component of a prosthesis. What characterizes a good implant, it is a balance successful between on the one hand a geometry adapted, including the surface quality of the substrate, and on the other hand the technically powerful implementation of a valid coating.

. : And criticisms concerning the resorption of the ha and the risk of remote osteolysis?

.: The is a physiological material prone to osteoclastic degradation just like any other mineral-bearing party of our skeleton. If this degradation occurs in a slow and controlled way, the ha could be replaced by bone while the remains of coating ha will be destroyed in a physiological and natural way by the human body: there is not matter with problems. This process depends much on quality of the coating. So indeed this coating is not good quality, a not controlled degradation can generate the remains salting out formed by harmful particles, with all the consequences which can result from it.
The remains salting out of hydroxyapatite sometimes put forward by the detractors of the hydroxyapatite, and supposed to come from a “not controlled” degradation is thus seen only for the coatings of poor quality. Thomas made into 93 in the USA a study concerning the comparative wear of polyethylene for similar metal heads coming from stems ha, cemented and with porous metal. Stems ha were recognized like inducing the weakest wear. Thus, association Ha-increase in articular wear is a myth
It is the same for “migrating” osteolyses whose no case was reported at the end of a recent clinical review published in the Books of teaching of , the radiographic results of more than 5000 stems ha established by Authors coming from different horizons. The explanation could lie in the intimate contact bone-metal permitted by the of apatite, and preventing the passage of the particles and remains between prosthesis and bone structures. As he was written in addition, the hydroxyapatite protects the bone from osteolysis due to the remains.

. : Can one speak about the hydroxyapatite like “biological cement”?

. : The hydroxyapatite could be actually regarded as biological cement as regards solidity of fixing in the short and medium term. However, this name which is placed in parallel with acrylic cement, can appear not very suitable long-term. Indeed, contrary to cement, the ha is intended to undergo a physiological degradation to be replaced by bone. A robust ostéo-integration bone-implant constitutes the finality of an implant with coating ha. Thus after having fulfilled its role, the hydroxyapatite can disappear gradually, without letting plane the risk of later potential disasters. Acrylic cement on the contrary can as for him still be likely to be degraded in the long run, without leaving of second valid line of defense.
The hydroxyapatite thus brought to the implant fixation a “biological” potentiality, not yet forwards for any of all the methods of prosthetic fixing used previously. The fixing of the prostheses with coating hydroxyapatite can be regarded as different from any other, in particular porous cement and metal. In this direction, the term of “third channel”, that we regularly used, seems me to be appropriate perfectly.

. : What is it coatings ha of knee prostheses?

. : Knees ha are forwarded under one day different. The technique of coating is worked out, although this problem can be now regarded as solved. The real difference, it is that as regards knees, success does not depend only on the capacities of fixing of the implant to the neighbouring bone, but also of a rigorous balance and an correct alignment of the mechanical axis of the lower extremity. Thus to obtain an initial mechanical stability can appear more difficult with a knee than with a hip.

. : Then can the hydroxyapatite appear reliable at a place and dubious with others?

. : Not. There do not exist specific differences between the various surfaces of implementation of the coatings ha, which it is about femoral components or of hip prosthese, or of femoral components or tibial of knee prostheses, even still of shoulder prosthese or tibio-tarsal implants the differences in results are explained by the degree of obtaining a sufficient initial mechanical stability to the interface to make it possible fixing by osseointegration to develop in a valid way. And for this reason of course exist very different conditions according to the anatomical localization.
Even if it were proven, in particular by , that a covered implant of ha and forwarded to will be able nevertheless to forward an ostéo-integration, which will be never the case of not covered implants, it is obvious that if these exceeds a critical point, this osteogenesis will not be able never to be carried out and it will be the failure. The difference between the various sites in implantation for a given coating thus does not hold with the coating itself, but with the mechanical conditions of prosthetic geometry, recipient site, and surgical procedure.

. : You speak about clinical outcomes, how to evaluate them in an objective way?

. : Certain tools are at our disposal as regards investigations, and in particular the radiography for which we developed the score MACAW, but also the osseous .
I am interested particularly in the , it is for me a tool of foreground for the scientific assessment of the arthroplasties, simply because it is likely to provide more precise information concerning the osseous answer with respect to the implant, in a period of time much shorter than the conventional methods. The period of observation of becoming implant can be thus considerably short cut, with in corollary an obvious benefit for all the parties concerned, including the patient

. : You quoted the score MACAW?

. : MACAW means “Agora ”. It is about a quantified score of radiographic evaluation of the femoral components of the uncemented prostheses, developed by the AGORA Group, which we had the occasion to publish in the Books of Teaching of devoted to the prostheses with coating hydroxyapatite, and to forward in complement at the time of a communication at the time of the last into 94. We will forward soon the slope this evaluation.
This score MACAW represents for us an significant improvement compared to the other methods of analysis of the parameters, and their quantified evaluation. Starting from a very broad data-processing basis and of a systematized confrontation of the clinical and radiographic data, we endeavoured to highlight certain parameters of potential risk, on the basis of the basic principle that certain signs of bone remodeling could potentially lead to problems, according to various degrees. Thus at the end of data-processing mixing several thousands of simulations radio-private clinics, according to a method corresponding to the calculation of risk factors of the insurance companies, we could allot an digital asset to each potential “risk factor”. The result is a simple figure from 0 to 6, of a handling corresponding to the quantified evaluation of Blackbird of and for clinical quotation. This score MACAW authorizes a radiographic of a series, at the individual or overall level, evolutionary evaluation in time. It also makes it possible to establish precise prognostic comparisons between various implants of geometry or different procedures of coating.

. : You are group chief executive AGORA, why this Group, which are the objectives?

. : Search in the field of csotcina.comedy was still here is little of time the fields of activity of a single personality. It is enough to refer to , , , Lord and others. Today the achievements of high-tech require the co-operation of all the scientific disciplines, with in corollary the need for a multidisciplinary co-operation at the same time enters and within the various disciplines. And this not only to generate sufficiently important series of number for the clinical judgment, but also to profit from an overall mechanism of “regulation in return” for each individual concerned separately. Thus the concept of groups directed towards a specific subject appears it like particularly gravitational, because it provides an ideal environment for the co-operation between clinicians, scientists, and engineers. We spoke much throughout this interview about Europe and of its scientific potential, the creation of this European group since 1990 answered this waiting
I thus could materialize the relations of very close cooperation founded since 1987 with Jean-Alain Epinette, who implied himself very precociously in this channel of the hydroxyapatite in France. Taking into account at the same time our joint conclusions concerning the promising future of the coatings hydroxyapatite as regards csotcina.comedic surgery, as well as need for clinical studies rigorous and equipped with suitable means for the study of the results, we decided Co-to found this Scientific Group AGORA. The AGORA is in fact “Apatite Arthroplasties”. We had appreciated in this name the Helene symbolic system of this gathering place of the ideas and knowledge of the Greek people, with the cradle of our civilization. Profiting from a logistic support of the Research center and Documentation of the Arthroplasties, based in , the AGORA largely could contribute to the development since then of knowledge as regards coating hydroxyapatite of joint prostheses.

. : Let us speak about the future: hydroxyapatite or other coatings ?

. : The coatings hydroxyapatite certainly do not have to disappear. However certain amendments of the elements can be planned to improve their biological potential. Thus their association with others made up or other methods of osseous stimulation is a gravitational idea. We will certainly not fail to note soon significant progresses in this direction. However, the basic principles of the of the coatings will be always of setting. An ideal coating is that which induces a robust ostéo-affixing in the shortest period of time, then disappears gradually while falling under the physiological process of bone remodeling, i.e. while being replaced by bone without leaving behind him persistent marks of its former existence. We are as of now very close to this result.

. : If one turns now towards the problems of polyethylene, friction and articular interface, that to think of the current evolutions: metal-metal, ceramics-polyethylene?

. : It is clear that joint surfaces of our prostheses represent from now on the main challenge for future progress of the prosthetic surgery. Although one can speak about promising options such as articular metal-metal, or ceramics, or the ionic bombardment of metal surfaces type the L-FIT, no element and no long-term follow-up allow reasonably, for the moment at least, to conclude in a clear way. Progress could also be under consideration for polyethylene itself, although one can consider it regrettable that these potential improvements of the existing components hardly impassions the polyethylene manufacturers, undoubtedly because it acts for them of a “marginal” market, and that they thus express little interest to invest in this type of prosthetic improvement. With my opinion however, it could be an possible option. At all events, we can only await the emergence of new technologies, perhaps ceramics on metal?

. : In do conclusion, how see you to it future of the coatings such as the hydroxyapatite?

. : The csotcina.comedic Community, everywhere in the world, is characterized by a relatively conservative approach with regard to the implant fixation. The rule is to confine itself (too much) a long time with the traditional methods of prosthetic fixing, while remaining perfectly conscious of their limitations. However, because at the same time of the increasingly marked control of the implants with coating hydroxyapatite, at the same time as of the publication of long-term excellent results of this type of implants in the columns of the independent reviews of the csotcina.comedic world, should note to us a fast progression of the hydroxyapatite to the international level.
In the long term, the negotiable instruments of this extension of the hydroxyapatite should initially make obsolete the other methods of fixing without cement, and in the second place, partially encroach on the market of the cemented prostheses. With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their elevated level of function activities
With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their high standard of functional activities, we will be able to only resort to optimal fixing that only the implants can offer.

. : , which are you?

. : I am before any csotcina.comedic surgeon, in post with the University hospital of Maastricht. I also occupy the functions of “senior ” to the head of the csotcina.comédique research service, within the laboratory of the Biomaterials of our University.
Beyond the hip surgery, and in particular the surgery of recovery, I can thus be interested particularly in search of the techniques relating to bone regeneration and the implant fixation.


: You and researcher, is this is thus at the same time clinician easy to manage, in an everyday activity?

. : The combination of an activity of surgeon and scientist being described as ideal, insofar as the problems encountered by the clinician are examined (and sometimes solved) by the researcher in the most direct way.
It should be recognized that it results a considerable workload from it to reconcile these two poles of activity at the same person. I try to organize my timetable consequently, say two thirds for my work of csotcina.comedic surgeon, and the last third party for the basic research and private clinics.

. : The name of the University of is often quoted in your work…

. : The Group of Search of has a very old fame as regards work on the biomaterials, in the medical field and in dentistry. We began our collaboration with this group with beginning of the year 80, starting from their experiments on the coatings hydroxyapatite (HA) in dental implementations.
In fact if one their work axes is devoted as for us to the , it is more on the plan of the manufactoring processes of materials, while our Group of Maastricht is mainly interested in the elements of biochemical and experimental search. In this direction, Maastricht and seem completely complementary.

. : Did you begin your work on the hydroxyapatite by Universitaire tradition, or personal conviction?

. : By personal conviction. I started to interest me in search on coatings ha because I was not satisfied by the methods of implant fixation available at the time. That one speaks about cement or porous metal, one finds a significant number of disadvantages during their use, primarily because of the nonbiological character of these materials. I then acquired the conviction that the hydroxyapatite and the others compounds could have to offer much more, and this certainty was not since then contradicted
I have in fact begun the implantations from femoral stems ha since 1986. The cups ha followed at the beginning of 87. This clinical experiment made following the multiple experimental work undertaken during the last decade, which had been able to show the superiority of the coatings hydroxyapatite, compared to the other methods used previously for fixing uncemented of the implants.

. : You in Maastricht, do you feel live particularly European?

. : Yes, I feel very European, but it is undoubtedly more than one choice of individual that about a place of residence. It is true however that Maastricht, as one of the cities more in the south of the Netherlands, always maintained the very close relations with Belgium and Germany. Here nearly twenty years that I live Maastricht, and I am very happy to state me European, especially since the opening of the borders of the European Union.

. : You have thus to applaud the creation of ?

. : Not only I applauded the constitution of , but I am one of the charter members. This offers to the European surgeons at the same time a challenge and a chance to work together under better conditions. There exists in Europe a fantastic potential of scientific knowledge, perhaps higher than what one can find in the USA. But because we are usually divided by problems of language or other barriers, we let flee a great number of opportunities to the Unis or in the Asian countries. offers a single chance to us to improve our collaboration between European countries and in the long term to restore our csotcina.comedic leadership on a world level.

. : What did you think of the first meeting of the in Peak last year?

. : This first congress in Peak revealed small problems of organization, because each country sends its “delegates”, and that it results from it sometimes from the situations close to the political meetings. It is in addition necessary to reconcile the requirements of timetable and the access of the greatest number of speakers, which is by definition the quadrature of the circle in the event of “open” society. In this direction, the problem of parallel meetings on similar subjects must certainly be corrected, with a segmentation according to the poles of interest, even if it is always of and hip surgery
One can however consider that this meeting was very profitable on the scientific level, would be only because it succeeded in proving that at the European level a great number of research tasks are in hand, and that we have to learn from/to each other much

. : “” American is an entity very special and closed, think that a reconciliation with the is possible?

. : The first of the things to be made for Europeans is to link itself. It is only once this aim reached which one could consider a closer cooperation with American. Still be necessary-you he initially to speak about equal footing with the US surgeons that this is the proof of its credibility and can acquire a sufficiently strong identity.

. : In connection with North-American surgeons, you with them, how do you consider them worked much?

. : I enormously have respect for the American surgeons because of their excellent standards of quality of care. On another side, and as a main part in consequence of the implication of the FDA in the development of modern technologies, the therapeutic guidelines tend to remain primarily “preserving”. We must do everything in Europe to avoid such an administrative brake with therapeutic progress. Obviously, new technologies must be evaluated according to very strict scientific criteria to avoid any harmful side-effect. But these methods of assessment should not in no case to prove Draconian at the point to keep the patients away of significant progresses which modern medicine can offer to them.

. : The “preserving” guidelines to which you made allusion slow down the hydroxyapatite in the USA naturally, which in is in Europe?

. : You know, even if the “” currently finds a gain of popularity in the United States, and even if the coatings hydroxyapatite are still difficult access for the whole of the American surgeons for administrative reasons, it does not remain about it less than certain prostheses ha are legally authorized on the US market, in particular the stem, since the Christmas Day 90! In addition, and little by little, these types of coating start to be dissociated from different “without cement”, and all the large american companies are interested in it, including ! Japanese and the other countries of “” tend to imply in a more precise way, and I would not be astonished that these countries open in the years to come in a very fast way to technologies ha.
As regards Europe, my impression is that there exists already currently a great interest for the hydroxyapatite in all the Community countries. A great number of research tasks relating to very a large range of parameters of fixing of the prostheses was published right now, and the clinical use of the covered implants of hydroxyapatite is in increase.

. : It seems that there are several qualities of ha; if one increases the number of prostheses ha, and thus of manufacturers, T it does not have there not a risk of degradation of the results?

.: The risk of discredit of which can suffer a relatively new technique such as the ha because of the poor results of bad coatings is real, and I want of it for proof the repercussion given to the USA with some fragmentary observations published by and Hoffmann. It will never be said rather indeed that the techniques of coating hydroxyapatite must be assumed by centers of manufacture particularly broken with these methods.
One however attends the multiplication of coatings ha commercially available. In terms of clinical results, there is for the moment between them more similar observations that points of difference. Nevertheless, with regard to the tissue answer in situ, of the significant differences probably exist between the various coatings, chemical composition methods of implementation. The components of crystallinity, from purity of the hydroxyapatite, thickness, density and recovery vary in a major way from one manufacturer to another. Consequently, the speed of ostéo-affixing and the degree of degradation can vary in a major way. Which will be the consequences of these variations, we can for the moment only apprehend it partially.
In practice, a coating low thickness (up to icrons) of high density and intermediate crystallinity implemented to the rough substrate of an implant whose geometry is adapted to a transmission stresses in charge, constitutes certainly a good approach.

. : To avoid the defective coatings, would be you in favor of a monopoly of manufacture of coatings ha?

. : Not, at all. The competition between various Research centres and of manufacture of coatings ha is in oneself an excellent element of stimulation and progress. But this is true only if each one of these Centers is implied in search to improve its characteristic produced. However force is to note that unfortunately many manufacturers are satisfied to copy certain products servilely. This is not only detrimental for scientific progresses, but also tends to accredit in the spirit of the csotcina.comedic Community the idea according to which it could suffice for a prosthesis to be painted in #FFFFFF to be valid, without being concerned with parameters of coating. We must expect some serious disasters on the plan of the clinical outcomes, simply because of bad copies of coatings ha implemented to bad implants. And then indeed this irrefutable fact can generate a bad name for the hydroxyapatite.
It will never be said enough, the coating itself is not the essential component of a prosthesis. What characterizes a good implant, it is a balance successful between on the one hand a geometry adapted, including the surface quality of the substrate, and on the other hand the technically powerful implementation of a valid coating.

. : And criticisms concerning the resorption of the ha and the risk of remote osteolysis?

.: The is a physiological material prone to osteoclastic degradation just like any other mineral-bearing party of our skeleton. If this degradation occurs in a slow and controlled way, the ha could be replaced by bone while the remains of coating ha will be destroyed in a physiological and natural way by the human body: there is not matter with problems. This process depends much on quality of the coating. So indeed this coating is not good quality, a not controlled degradation can generate the remains salting out formed by harmful particles, with all the consequences which can result from it.
The remains salting out of hydroxyapatite sometimes put forward by the detractors of the hydroxyapatite, and supposed to come from a “not controlled” degradation is thus seen only for the coatings of poor quality. Thomas made into 93 in the USA a study concerning the comparative wear of polyethylene for similar metal heads coming from stems ha, cemented and with porous metal. Stems ha were recognized like inducing the weakest wear. Thus, association Ha-increase in articular wear is a myth
It is the same for “migrating” osteolyses whose no case was reported at the end of a recent clinical review published in the Books of teaching of , the radiographic results of more than 5000 stems ha established by Authors coming from different horizons. The explanation could lie in the intimate contact bone-metal permitted by the of apatite, and preventing the passage of the particles and remains between prosthesis and bone structures. As he was written in addition, the hydroxyapatite protects the bone from osteolysis due to the remains.

. : Can one speak about the hydroxyapatite like “biological cement”?

. : The hydroxyapatite could be actually regarded as biological cement as regards solidity of fixing in the short and medium term. However, this name which is placed in parallel with acrylic cement, can appear not very suitable long-term. Indeed, contrary to cement, the ha is intended to undergo a physiological degradation to be replaced by bone. A robust ostéo-integration bone-implant constitutes the finality of an implant with coating ha. Thus after having fulfilled its role, the hydroxyapatite can disappear gradually, without letting plane the risk of later potential disasters. Acrylic cement on the contrary can as for him still be likely to be degraded in the long run, without leaving of second valid line of defense.
The hydroxyapatite thus brought to the implant fixation a “biological” potentiality, not yet forwards for any of all the methods of prosthetic fixing used previously. The fixing of the prostheses with coating hydroxyapatite can be regarded as different from any other, in particular porous cement and metal. In this direction, the term of “third channel”, that we regularly used, seems me to be appropriate perfectly.

. : What is it coatings ha of knee prostheses?

. : Knees ha are forwarded under one day different. The technique of coating is worked out, although this problem can be now regarded as solved. The real difference, it is that as regards knees, success does not depend only on the capacities of fixing of the implant to the neighbouring bone, but also of a rigorous balance and an correct alignment of the mechanical axis of the lower extremity. Thus to obtain an initial mechanical stability can appear more difficult with a knee than with a hip.

. : Then can the hydroxyapatite appear reliable at a place and dubious with others?

. : Not. There do not exist specific differences between the various surfaces of implementation of the coatings ha, which it is about femoral components or of hip prosthese, or of femoral components or tibial of knee prostheses, even still of shoulder prosthese or tibio-tarsal implants the differences in results are explained by the degree of obtaining a sufficient initial mechanical stability to the interface to make it possible fixing by osseointegration to develop in a valid way. And for this reason of course exist very different conditions according to the anatomical localization.
Even if it were proven, in particular by , that a covered implant of ha and forwarded to will be able nevertheless to forward an ostéo-integration, which will be never the case of not covered implants, it is obvious that if these exceeds a critical point, this osteogenesis will not be able never to be carried out and it will be the failure. The difference between the various sites in implantation for a given coating thus does not hold with the coating itself, but with the mechanical conditions of prosthetic geometry, recipient site, and surgical procedure.

. : You speak about clinical outcomes, how to evaluate them in an objective way?

. : Certain tools are at our disposal as regards investigations, and in particular the radiography for which we developed the score MACAW, but also the osseous .
I am interested particularly in the , it is for me a tool of foreground for the scientific assessment of the arthroplasties, simply because it is likely to provide more precise information concerning the osseous answer with respect to the implant, in a period of time much shorter than the conventional methods. The period of observation of becoming implant can be thus considerably short cut, with in corollary an obvious benefit for all the parties concerned, including the patient

. : You quoted the score MACAW?

. : MACAW means “Agora ”. It is about a quantified score of radiographic evaluation of the femoral components of the uncemented prostheses, developed by the AGORA Group, which we had the occasion to publish in the Books of Teaching of devoted to the prostheses with coating hydroxyapatite, and to forward in complement at the time of a communication at the time of the last into 94. We will forward soon the slope this evaluation.
This score MACAW represents for us an significant improvement compared to the other methods of analysis of the parameters, and their quantified evaluation. Starting from a very broad data-processing basis and of a systematized confrontation of the clinical and radiographic data, we endeavoured to highlight certain parameters of potential risk, on the basis of the basic principle that certain signs of bone remodeling could potentially lead to problems, according to various degrees. Thus at the end of data-processing mixing several thousands of simulations radio-private clinics, according to a method corresponding to the calculation of risk factors of the insurance companies, we could allot an digital asset to each potential “risk factor”. The result is a simple figure from 0 to 6, of a handling corresponding to the quantified evaluation of Blackbird of and for clinical quotation. This score MACAW authorizes a radiographic of a series, at the individual or overall level, evolutionary evaluation in time. It also makes it possible to establish precise prognostic comparisons between various implants of geometry or different procedures of coating.

. : You are group chief executive AGORA, why this Group, which are the objectives?

. : Search in the field of csotcina.comedy was still here is little of time the fields of activity of a single personality. It is enough to refer to , , , Lord and others. Today the achievements of high-tech require the co-operation of all the scientific disciplines, with in corollary the need for a multidisciplinary co-operation at the same time enters and within the various disciplines. And this not only to generate sufficiently important series of number for the clinical judgment, but also to profit from an overall mechanism of “regulation in return” for each individual concerned separately. Thus the concept of groups directed towards a specific subject appears it like particularly gravitational, because it provides an ideal environment for the co-operation between clinicians, scientists, and engineers. We spoke much throughout this interview about Europe and of its scientific potential, the creation of this European group since 1990 answered this waiting
I thus could materialize the relations of very close cooperation founded since 1987 with Jean-Alain Epinette, who implied himself very precociously in this channel of the hydroxyapatite in France. Taking into account at the same time our joint conclusions concerning the promising future of the coatings hydroxyapatite as regards csotcina.comedic surgery, as well as need for clinical studies rigorous and equipped with suitable means for the study of the results, we decided Co-to found this Scientific Group AGORA. The AGORA is in fact “Apatite Arthroplasties”. We had appreciated in this name the Helene symbolic system of this gathering place of the ideas and knowledge of the Greek people, with the cradle of our civilization. Profiting from a logistic support of the Research center and Documentation of the Arthroplasties, based in , the AGORA largely could contribute to the development since then of knowledge as regards coating hydroxyapatite of joint prostheses.

. : Let us speak about the future: hydroxyapatite or other coatings ?

. : The coatings hydroxyapatite certainly do not have to disappear. However certain amendments of the elements can be planned to improve their biological potential. Thus their association with others made up or other methods of osseous stimulation is a gravitational idea. We will certainly not fail to note soon significant progresses in this direction. However, the basic principles of the of the coatings will be always of setting. An ideal coating is that which induces a robust ostéo-affixing in the shortest period of time, then disappears gradually while falling under the physiological process of bone remodeling, i.e. while being replaced by bone without leaving behind him persistent marks of its former existence. We are as of now very close to this result.

. : If one turns now towards the problems of polyethylene, friction and articular interface, that to think of the current evolutions: metal-metal, ceramics-polyethylene?

. : It is clear that joint surfaces of our prostheses represent from now on the main challenge for future progress of the prosthetic surgery. Although one can speak about promising options such as articular metal-metal, or ceramics, or the ionic bombardment of metal surfaces type the L-FIT, no element and no long-term follow-up allow reasonably, for the moment at least, to conclude in a clear way. Progress could also be under consideration for polyethylene itself, although one can consider it regrettable that these potential improvements of the existing components hardly impassions the polyethylene manufacturers, undoubtedly because it acts for them of a “marginal” market, and that they thus express little interest to invest in this type of prosthetic improvement. With my opinion however, it could be an possible option. At all events, we can only await the emergence of new technologies, perhaps ceramics on metal?

. : In do conclusion, how see you to it future of the coatings such as the hydroxyapatite?

. : The csotcina.comedic Community, everywhere in the world, is characterized by a relatively conservative approach with regard to the implant fixation. The rule is to confine itself (too much) a long time with the traditional methods of prosthetic fixing, while remaining perfectly conscious of their limitations. However, because at the same time of the increasingly marked control of the implants with coating hydroxyapatite, at the same time as of the publication of long-term excellent results of this type of implants in the columns of the independent reviews of the csotcina.comedic world, should note to us a fast progression of the hydroxyapatite to the international level.
In the long term, the negotiable instruments of this extension of the hydroxyapatite should initially make obsolete the other methods of fixing without cement, and in the second place, partially encroach on the market of the cemented prostheses. With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their elevated level of function activities
With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their high standard of functional activities, we will be able to only resort to optimal fixing that only the implants can offer.

. : In do conclusion, how see you to it future of the coatings such as the hydroxyapatite?

. : The csotcina.comedic Community, everywhere in the world, is characterized by a relatively conservative approach with regard to the implant fixation. The rule is to confine itself (too much) a long time with the traditional methods of prosthetic fixing, while remaining perfectly conscious of their limitations. However, because at the same time of the increasingly marked control of the implants with coating hydroxyapatite, at the same time as of the publication of long-term excellent results of this type of implants in the columns of the independent reviews of the csotcina.comedic world, should note to us a fast progression of the hydroxyapatite to the international level.
In the long term, the negotiable instruments of this extension of the hydroxyapatite should initially make obsolete the other methods of fixing without cement, and in the second place, partially encroach on the market of the cemented prostheses. With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their elevated level of function activities
With my opinion, there will be always, at least still for a long period, a market for the cemented implants, would be this only for one problem of lower costs among oldest and osteoporotic patients. On the other hand, for the patients who require a particularly powerful prosthetic fixing and of long life, because of their high standard of functional activities, we will be able to only resort to optimal fixing that only the implants can offer.