. : When did you carry out your very first total arthroplasty of hip?

: I posed my first , , in 1969. I started with the couple
of friction metal/metal. This moment, the couple metal/metal and the plastic couple metal made debate. Which was going to prove to be higher than the different one? Both had partisans and a strong concept. I think that the challenge was different: for the plastic, it was a question of being able to support the forces and the movements which intervene in the hip joint, and for the couple metal/metal, the problem was to put face-to-face two hard surfaces. The first plastic associated with metal was the Teflon which did not have a good reputation. It is about at this time which it appeared obvious that polyethylene forwarded certain real advantages. However none the implants had received the adoption of the FDA.

. : When did you turn towards polyethylene?

: I have in fact established few prostheses metal/metal. The data of the time seemed to privilege the plastic couple metal/. Retrospectively, I can say that the reason of this decision less held with the problems of the hinge itself than to the problems of fixing. The couple metal/metal raised more difficulties with first cemented than with . I thus had to consider the couple metal/polyethylene. I then directed myself towards the modular prostheses with curved stem with head of diameter isters I posed about 150 of them.

. : In were years 60/70, which the urgent problems to solve?

: At the beginning, the main problem was the couple of friction. The first attempts to solve this problem showed very average results. The prostheses figure/metal contained of the Teflon which gave poor outcome. The second problem was the infection. The first series of had an infection rate close to 10%. Joint surfaces were what worried primarily but the infection “was put across its path” and it had there to face to solve its true problem. Its tenacity and its obstinacy contributed much to make progress the surgical asepsis. The third problem was fixing. Fixing was the main weakness of the first prostheses metal/metal. That they are mechanical defects of anchoring or septic Clerc's Offices, the loss of fixing with osteolysis quickly seemed an essential concern. It is finally which had the best approach of this problem, and its medium-term results were rather good.

. : At which time was raised the problem of osteolysis?

: Surprising thing, the problem of osteolysis was recognized rather late. Since November 1962, one used of the LDC and polyethylene, and one posed much . If you seek the publications on osteolysis, you will see that the aforementioned started to be recognized like a real process of deterioration about the middle of the Seventies. made a publication in 1976, we made a publication in 1976. It thus was necessary 14 years so that this phenomenon is finally recognized. In 1976, we had 4 cases of severe bone destruction around total prostheses of hip, and I thought that it was to be a question of a malignant affection: tumor, metastasis or myeloma! All that the biopsy showed was the presence of macrophages. I was sure that it was about a malignant process. The published our 4 cases of osteolysis: that seemed absurd! 40 cases or 400 cases of agreement, but they accepted a paper with 4 cases! in fact this publication was very revealing of a certain awakening: what can it occur well? It is very interesting in this respect reconsidering the first work of on the Teflon and some of its work on corpse. It gave a report of osteoclasts and macrophages. It brought back a considerable osteolysis with the Teflon. He spoke about granuloma, but it was about a mysterious process and he did not find any good explanation. Therefore, there were data elements, but the puzzle was not assembled. It is only about the middle of the Seventies that the idea of a opposing reaction started to gain the spirits. And there the questions arose: how that does it occur? which is the cause? The macrophage was the airframe-key but was not regarded as being the person in charge of the bone resorption.

. : Why then one did not indicate polyethylene as causes major this osteolysis?

: Because osteolysis is the consequence of a single pathology. This mechanism had never been described in the medical history. In addition, did not speak about osteolysis but about infection. He told “We have strange cases of bone destruction; we cannot identify bacteria, but no doubt that it is indeed an infection”. published severe cases of osteolysis, and stated “That is due to a mobilization of the stem. If you do not have a mobilization, you do not have this phenomenon.” Both stuck to the process, without seeing its physiopathology. This pathology is single because it requires the generation of fine particles in the body, and this over one long period. As that had been observed never before, people were not “packaged”. They thought “Ca is not completely like tuberculosis, but that resembles it much. It must be a or something of this kind”. It was necessary to await the last quarter of the 20th century for one understands the mechanism of this disease. I thought, during the recoveries, that the membrane which we extract from the femur, and with the back of the loosened cup, was to be biologically active. There was not an other explanation. With and a pathologist, we started to study this membrane that everyone had habit to throw until there. In histology, one told us that it was about fibrous tissue, of macrophages. We were to study this membrane with modern microbiological techniques. We discovered and . We had found: it was that the active biological process. From there, all the remainder of molecular biology rose. It became clearly that the macrophages constituted an answer to the particles, and that with time, they activated osteoclasts, leading to the bone resorption. We published our observations in 1983. From these observations, that became interesting because we wondered whether we could get rid of these microparticles…

. : You made since many other contributions to the development of the total joint replacement of hip.

: The thing of which I am more to trust is the fact of having faced several problems during my career, where they were, without me to attach more particularly to one or the other. At the beginning, fixing was a problem, the infection was a problem We then worked on the improvement of the techniques of cementing and the drawing of the implants. I designed the first cup revisable metal-back in 1971. What worried me also at the time, it is that the patients died of pulmonary embolus. I thus did my first work on the . When one reconsiders there, I started to use the in 1962. We evaluated the stake: yes, the blood loss was more important but the patients did not die any more, therefore that was worth the sorrow. With regard to polyethylene, I am not a specialist in this material, but I thought that we needed a better couple of friction. It does not matter the solution, but a solution was needed. Therefore, during the 13 last years, we worked on this problem. And there, I return from there so that I told previously, if there is a problem, approach it. And I would like that it is that the governing idea of all my work.

. : One little to tackle the problems but to be misled!

: yes and the “disease of cement” in is an good example. Many the made errors, were it by intelligent people who worked hard and made of their better, but starting from incorrect informations. As I already mentioned, had brought back cases of osteolysis by allotting them to the infection. as for him, allotted them to mechanical problems. Others considered that it was about a “disease of cement”. It was natural to suppose that since the implants were cemented, and that cement split up, it was about a reaction due to cement. Also when we had cases of osteolysis on prostheses without cement, that was a true surprise. I remember it very well, at the time of the Congress of the Society of the Hip in Montreal, I saw 3 cases of osteolysis on prostheses without cement. How was this possible? I called Galante and “, I told him have 3 cases of osteolysis on prostheses without cement”. It was one Saturday afternoon. It immediately called his collaborators, and on more than 200 cases, they had of them also 3. We were to thus reconsider all that we knew about the subject. Interesting thing, I had seen 1 case of John on a hip PCA, but I did not want to make a deal of it against , titanium against chromium-cobalt. I thus called John and told him “John, you have a case of osteolysis on a prosthesis without cement. That do think about it you?” He answered “No idea”. I then “Why wouldn't we share told him your cases with ours to make a publication as soon as possible so that everyone starts to be concentrated on this problem? We waited 14 years, of 1962 to 1976 to publish on osteolysis on total prostheses of hip cemented, do not start again. And it was of agreement. We eliminated all that could rise from the false arguments and very posed flat on the table.

. : In a certain manner, the misunderstanding on “the disease of cement” had pushed many surgeons towards the cementless implants.

: Absolutely! The main argument for without cement was the elimination of the risk of the “disease of cement”. By certain sides, that was very positive, by others, not. In terms of major error, there was the concern relateds to the effect of surface on the femoral implants: thus, we had asked to the manufacturers that the porous titanium coating recover all the circumference of the implant partly . But at this time, that was not possible technically; one thus left two smooth areas of junction between surfaces and this proved very bad. It should be said that at that time, we did not have either a good appreciation of articular space, distal migration of the particles along such a smooth area, and a “gasket” which creates for itself a complete cementing in the case of or of a good ” without cement “. We would say - although the opinions defer on this subject in Europe - that the cup of the prosthesis Harris Galante represented an enormous progress. We have just re-examined a consecutive series of 263 recoveries at 12,5 years; 5 prostheses only out of 263 were loosened. Isn't this astonishing? In same time, the femoral implant Harris Galante proved to be a true disaster. At 10 years, 60% of the implants forwarded an osteolysis. It is the perfect example owing to the fact that when you test something again, you can never be sure long-term outcome. The cup went very well, whereas the femoral stem was a failure, because of this problem of coating.

. : From when the problems of corrosion were recognized? And is this important for you?

: I do not think that it is really important today. The great change was the passage of the implants run with the forged implants. That solved many problems. That practically eliminated the risk from rupture of implant, made it possible to amend the cervico-diaphyseal angle, and to refine the coll We also improved materials. So corrosion is not main problems for me. We improved the cones where a strong corrosion occurred. Moreover, I think that two metals, titanium and chromium-cobalt, contributed much to solve this problem.

. : How the idea to improve the couple of friction did come to you?

: It became clear, with the beginning of the year 1976 and even more in the Eighties - and I published several items on this subject - that the problem number 1 in the long run would be osteolysis. But much of people did not recognize that and stuck to other problems. One of the reasons for which it appeared to me that osteolysis was the true problem, is the fruit of a work which we made to discover from which the radiological edging between cement and the wall came. Was this a reduction in the stresses or on the contrary an increase in the pressures which led to the bone resorption? Or were there of monomer with the passing of years? We set up a program of explantation and method at a systematic study of these implants. Most attractive is that we discovered what it was. The resorption of the bone behind cement for the cemented prostheses, but also in the prostheses without cement, is caused by macrophages because of migration in this particulate remains area. Therefore, it was recognized that the cause of osteolysis was the presence of particles: particulate metal, cement, EP, hydroxyapatite, any remains. We were to thus limit the number of these particles. And I told “Design a better hinge”. Curiously, we did not start with materials. And that because I was dissatisfied with the existing simulators of hip, most current being those with reversed system and biaxial locking. Indeed, even if we discover a better material, how were going I to convince the opinion that it was really going to make a difference? I needed a simulator of hip which functions in order to prove the superiority of a new material. In 1980, We thus built our own simulator of hip. And there another very interesting history started. We contacted engineers, Dr. and and with MIT. We designed our own simulator of hip in collaboration with a society affiliated to MIT, called . We really devoted to it many time, money, and efforts. We tested conventional polyethylene there during illion cycles, without noting wear: the machine thus did not function like a hip. We were very disappointed. We very tested: to increase speed, to slow down speed, to increase the charge, to control the temperature…. and nothing went. It occurred something in the hip joint which we do not seize. About at that time, we observed better on our prostheses what occurred on the surface polyethylene. At the time of the functioning, when you cross the legs, climb…. the fibers are sheared. The wear of polyethylene rises from these mechanisms what nobody up to that point had understood. On our initial simulator of hip, we did not reproduce these movements. We thus took very again and integrated the four movements, abduction, adduction, external internal rotation and, bending, extension. And suddenly, that went exactly as in the human body.

. : Summers you sure that your test machine behaves like a natural hinge?

: I am not certain to 100% but almost. The reason for which I say that is that initially, we studied only the functioning, then the climb of staircases, to 2 Hz, then to 1 Hz, then the everyday activities: to take 100 pitches, to stop one minute, to take 5 pitches, to stop one minute, to climb, to stop one minute. We studied that with a model of wear to 3 bodies, under charges 3 times higher than the normal, under various conditions. We controlled the temperature of the fluid; we made controls with 37°C, which many tests do not provide. We had a sensor of effort on each station. Very often indeed, one observes variations from one station to another. I wanted to know exactly which was the charge implemented, about each station. We were able to reproduce the form of wave of each movement. We measured the temperature practically on the level of the hinge. We drilled a hole in the femoral head with 300 µ of surface to place a thermal sensor there, so that we could know what occurred on the surface.

. : Is there a variation in temperature?

: Yes, it is the temperature is increasingly higher there.

. : Because of friction?

: Absolutely. The temperature rises 37°C with approximately 45°C. It is what occurs in the human body. This stage, for me, it did not matter that the best hinge is “metal/metal”, ceramic ceramics/or contains polyethylene. I wanted a better hinge, it is all. But now, we knew finally the mechanism of wear of polyethylene. The whole was of knowing how to prevent it. I contacted a friend instructor in chemicals with MIT and exposed to him the problem of these lesions of surface. How to make to prevent this? Its answer was “It is simple: the reticulation.” Therefore, 8 years later, we carried out the reticulation of the polyethylene which makes it possible to improve the characteristics of wear. First of all, the reticulation was carried out with the state of merger. We eliminated the free radicals thus because with high temperature they recombine.

. : Was the mechanism of wear solved in 1992?

: We published only later, but the mechanism itself was understood in 1992.

. : In 2003, which prediction can you give to your patients, in terms of durability of an hip prosthese?

: Allow me to quote “I never make predictions, in particular on the future”. But if you grant to me then that the prediction of the future comes under the field of the random one, I want to do one well. We now have the means of obtaining a good anchoring of the implants and we have excellent couples of friction. I thus do not see why we could not count on 30 years a prosthetic durability. There will be a small percentage of failures which had with the technical errors, the infection, or other causes, but I do not see any reason so that we do not consider, even at the young patients of approximately 35 years, one prosthetic lifespan 30 years or more. If you read the reports 25-30 years from retreat on the first prostheses, the results are astonishment good; 70% are always in place. An experienced surgeon who chooses a good technique - because it exists many manners of operating which it carries out correctly, can reasonably count on 30 years a prosthetic durability.

. : Vis-a-vis are the partisans of the couple of “hard” friction, which the arguments in favor of polyethylene?

: It is necessary well to make the distinction between old polyethylene and the new one. You must show that this new material is completely different, and not that it is better. “You did not tell: there are 18 years of retreat on the ceramic ceramic couple, 18 years of retreat on the couple metal/metal, and no clinical study on polyethylene; forgery! it is a lack of information.” There exist actually the information considerable and documented well on each type of hinge. It is not an novel idea. In the second place, it is necessary to study other currently available information, in vitro data. The FDA imposes tests during illion cycles; we, we went up to 2illion cycles. Many of other laboratories confirm our results. Preceding “improved” polyethylenes known as which underwent successfully all laboratory testing, were clinical failures. The case of is very interesting. did not make a success of lab testings. There does not exist any study which shows a reduction in wear. The only study of wear made in a center of the hip on was biomechanical, and there was no difference. In addition the promoters never proposed wear. They never said less wear, they said less creep, a different module. It was a splendid example of marketing: one spoken forever about reduction of wear because they did not have there data showing it. In addition, the phenomenon of oxidation really had never been studied. However the problem of oxidation was considerable. The science of the chemicals of polymers largely improved. We learned how to eliminate the free radicals, how to obtain the reticulation. We learned that it is not necessary to go up to 100 , like ; 10 are enough, beyond, you do not obtain anything better. We know that 10 are more effective than 5. We thus acquired an large amount of new knowledge. We learned that when one one of the components at the end of 2 years (whatever is the reason), surface is dreadful.

We were then interested in a special property of the polyethylene, which one calls the memory of form. We discovered that if one takes
an unspecified, conventional or polyethylene, it is covered with a small crust on the surface. On conventional polyethylene, this crust wears, leaving a smooth surface. But on polyethylene, it remains and does not wear, and the apparent negotiable instrument is dreadful. But if you heat material, thanks to the memory of form, it takes again its original aspect and you find the marks of machining of 10 µ thickness!!

. : Which conclusions in practice?

: For there, it is necessary to choose between the couple with hard friction and polyethylene. With the couple metal/polyethylene, I do not have a problem of , of conflict, metal ions, I can put an insert at edge, in the event of repeating luxation I can put a constrained insert, and I do not have to amend my procedure. If I put the cup too high or if I have a problem of microcomputer-separation, I will not have wear by impact of the femoral head. With regard to the ceramic ceramic couple, the marginal peeling of the inserts due to the negotiable instrument of cam is a problem; the risks of rupture of implant improved well, but I suppose that there are still some cases, whether it is on the level of the head or the cup. If one tries to avoid peeling by adding a metal edge, one finds with a potential conflict metal/metal, titanium against titanium, and it is a very bad contact. We read all of the reports on the notches of the femoral neck; when that arrives, you then start to have metal particles in the ceramics hinge.

In the event of luxation with a polyethylene cup, the head is not damaged. You can position it back. In a couple metal/metal or ceramic ceramics/, surface is likely to be damaged. In these systems ceramic ceramics/, you have only little choice lengths of neck…

. : What do you think of the problem of the rebuilding of osteolysis?

: Initially, it would be well to be able to stop the process at the patient. I am only moderately optimistic in this respect. If you use an anti TNF alpha, you can stop the process, as one will be able to show it during the next years. There exists now a systemic product innovating which makes it possible to discuss osteolysis but has harmful negotiable instruments in addition. Conscious of the complexity of molecular biology, I am thus relatively anxious on the fact of stopping a chemical channel complexes, just to control the local reaction. I know that others will manage to solve the problem, but I prefer to concentrate on the hinge and to try to stop the generation of particles. With regard to the operative procedure, we are very satisfied with the rebuilding with the hemispherical cups fixed by screw, and with the compacted Clerc's Offices, if necessary. In this spirit, trabecular metal can prove to be a remarkable complement. The use of metal trabecular in the place of grafts seems very promising. Femoral side, the majority of the problems can probably be solved thanks to the variety of the modular femoral implants long stem, and of the femoral Clerc's Offices in the event of loss of massive substance to the upper end of the femur. These various options go extremely well. It is astonishing to see progress of the surgery of overhaul. Now, the majority of the cases of recovery - with some exceptions - have very a good long-term result. In addition, the majority of the cases of recovery relate to less active patients. The most important osseous rebuildings that we practice are of the 1/2 proximal femurs, though seldom, practically never of femoral heads in the , and very rare cases, compacted parcelled out Clerc's Offices on the side , exceptionally on the femoral side.

. : What holds the future for us?

: Heaps of things! I think that it is important to understand the concept of the “cream slice”. I.e. the resorption sleeps by layer of the femoral cortical bone. If we were not mistaken on our evaluation, the next major problems will be the osteopenia by inactivity. That already but not exists like chronic problem. When patients operated successfully at the 30 years age reach 65 years, they are likely to have lost a certain quantity of bone on the level of the proximal femur. That starts as of now and I think that it will be that the next problem.