1. Introduction
1.1. Reasons and Methods of creation of the current prostheses of ZweymĂŒller
The questions that I was posed about the stems of ZweymĂŒller of the first generation 1979-1985, with the creation of which I did not take part, appeared quickly during the operational assistances of training of the new users to the innovating procedure required by this prosthesis.
After having founded in 1977 the French subsidiary company of AlloPro (endoPROthĂšses ALLOplastiques), which was close to the Swiss group Sulzer, I added an activity new and enthralling to my administrative duties.
Thanks to my already long experiment by Carl Zeiss Foundation of the sterile operational assistances to train the new operators in micrurgy, I introduced the sterile operational assistance in orthopedy. Initially for the cemented prostheses, then for the prostheses of knee, and since 1981 for the implantation of the stems without cement.
The sterile operational assistance with the first implantations made it possible to the Orthopedists to shorten the period of training for the new prostheses and to obtain good performances as of the first implantation. For this time, the assistance has become normal, accepted, and sometimes essential.
During many operational assistances, of 1981 to 1984, during the trainings of the new users to the novel method operational necessary for the prostheses of ZweymĂŒller, I quickly put myself questions about the stems of ZweymĂŒller of the first generation.
I noted that the stems without cement of ZweymĂŒller of the first generation of 1979 of a rather primitive design, were drawn flat and of face like a radiography, without taking account of the third dimension, antĂ©ro-posterior.
I understood the need for designing these implants from a scientific and either empirical point of view and thus for applying mathematics available and for developing of them news, specific to this branch.
1.2. Already at the beginning, problems of sizes
Naturally, the patients require various sizes of implants, because of their size, according to their age and their physical activity. The prostheses of first generation of 1979 were of course available in several sizes, but the sizes of this series were spread out in a disorder and an absence of overall picture which have surprised me.
Of course in many cases one found an satisfactory adequacy between the needs for the patient and one for the stems available in the series so that the implantation proceeds without apparent problem and that the continuations are satisfactory for the operator and acceptable for the patient, but for approximately a patient on four, one was far from having the ideal stem.
The inadequacy was already visible being prepared of the diaphyse and remained observable in the clinical continuations.
It is the whole of these observations, cumulated during 4 years, which led me, at the beginning of 1984, to propose, with the manufacturer and the medical author, the principle of a recasting of the series of implants which would take into account my many observations and their analysis.
1.3. Conservation, but also improvement of the principle of implantation
a corriger With regard to the process of establishment itself, introduced by Professor ZweymĂŒller, the preparation of the femur with graters assembled on a coaxial hammer, the principle of the rectilinear stem of rectangular section, his self-locking without cement by impaction in the prepared channel, I was a convinced defender.
And my position is unchanged later 40 years. It was important for me to preserve these principles in the new evolution, including in the complete recasting of the system on mathematical bases.
1.4. Which motivations led me to undertake this work?
With my passage in 1977 of the field of scientific optics to the field of orthopedy, I was astonished and disappointed by the simple design of the orthopedic implants. These implants were designed by gropings and successive tests besides far from effective.
Since in the field of the orthopedic implants, no progress or any retreat can be noted objectively in less than 10 years of clinical application, the evolution by empirical processes is dedicated to the failure.
The evolutions remain closer to the Brownian movement than of the straight line because each positive or negative observation falls into the lapse of memory because of slowness from the evolution. Because of this lapse of memory, a new originator can âreinventâ and reapply an already rejected technology 20 years before, (for example, certain couples of gliding metal-metal), because of the clinical failures noted, but remained confidential.
1.5. Were my competences adapted?
Within the framework of my general-purpose studies and my former track records I hope to have gathered the majority of necessary competences to carry out the complete creation of system ZweymĂŒller-SL AlloPro, called thereafter AlloClassic:
The comprehension of the problems of spreading out of the sizes (Method of the Optimized Sizes) resulted from my studies of mathematics and statistics, but also of the experience gained at the time of my participations in work, on the one hand on the microscopic analysis of distribution of particles and on the other hand on the distribution of the sizes of the osseous cells in the study of the treatments of the osteoporosis.
My studies of mathematics, numerical calculation, of geometry, enabled me to conceive new mathematical developments applying in a concrete way to the implants the concepts of vector space with multiple dimensions (Method of the Growth Factors).
My studies in Master of Computer Science enabled me to conceive initially, to then write all the software requirements to constitute a system specialized for creation and the development of orthopedic implants. Thanks to the simulation and the observation of the forms on virtual prototypes, this method made it possible to jump several stages of settling, in comparison with the successive prototypes produced in workshop.
1.6. Short return on my studies
only one part was used for to create orthopedic implants:
1962 Baccalaureat Mathematics.
1962-1965 School of Applied Optics of Paris.
1964-1970 Faculty of Science of Paris - Sorbonne, many certificates, of which Physical Optics with the extraordinary Professor Maurice Françon, Quantum optics, Fundamental Physics, Mathematical Techniques of Physics, Quantum Mechanics, Crystallography, Spectroscopy and Chemical bonds, Data processing, etc
1971-1973 University of Paris-Dauphine, IAE (Institute of Administration of the Enterprises, 3rd cycle).
1.7. Short return on my activities and my expérience
My studies and my intense and enthralling community activities were often simultaneous.
1962-1977 Consulting Engineer by Carl Zeiss France: Microscopy, Microsurgery, Spectrophotometry, Ophthalmology. Design of solutions for research, assistances in microsurgery.
1970-1971 Military Service: Hospital Val-de-Grace, Paris, Department of health of the Armies, Research in Ophthalmology, 200 operational Assistances in Micrurgy.
1975-1979 Lecturer for the IBMH of the University of Technology of Compiegne, postgraduate teaching to Biomedical Engineers and Hospital: Microscopy, Micrurgy, Design of High Aseptic operating rooms.
1977-1991 Creation and direction in France of subsidiary company ALLOPRO (EndoPROthĂšses ALLOplastiques) Prostheses of hip, of knee, elbow, cement. conferences of formation, 600 sterile assistances of knee, 400 of hip.
1989-2005 Creation of the research department Deckner-Optimization, Orthoconcept, complete design and calculation of ready to produce prostheses.
1991 âtechnicalâ founder of the group PLUS Orthopedics, alone scientific and single originator of the Plus prostheses during two years. I had finished several projects before the foundation.
1989-2004 Member of the committees of standardization of surgical implants AFNOR (France), CEN (Europe), ISO (international): active participation to the drafting of all the standards on the prostheses.
1.8. Creation of a specialized computing system
For that, as no adapted software was available in 1984 on the market, it was necessary to invent and write, without reuse of existing elements, a software of description of the geometrical properties of the implant having its specialized language, a software of Parameter Base, a software of graphic representation, and especially a computation software allowing the simultaneous calculation of all the sizes of a series starting from the same set of parameters.
It is the 37Ăšme series of virtual prototypes which was used to produce series ZweymĂŒller-SL. This prosthesis is still distributed nowadays under the AlloClassic denomination. No modification of the single series of constructed and tested real prototypes at the end of 1984, was necessary. The experimental implantations in laboratory of anatomy were, as of the first meeting, very conclusive and induced any correction neither of dimensions of the implant nor of the distribution of the sizes. Professor ZweymĂŒller took note of this new series of implants during this meeting.
The bulky work of design of AlloClassic was carried out independently of my professionnal activity, at home in Paris in my personal office, on my equities, without financial support and external technological contribution of AlloPro or Sulzer.
The series was manufactured starting from the tables of coordinates, exact for the micron, which I dispatched with the Production without providing of theoretical explanation on the processes used, neither at the research department of AlloPro nor with Karl ZweymĂŒller itself which will take note of it with the reading of this document 28 years later.
On several occasions, I tried to provide some theoretical explanations to my interlocutors who did not see the interest of it. I gave thus up making it and continued the development without deepened communication, but by dispatching only the numerical data, until the least detail, essential to the production.
1.9. My historical Models
Without using their achievements directly, it is the way of thinking of these great men who was used to me as guiding line for my work.
1.9.1. Ernst Abbe
To improve the usual methods of design of the prostheses, which did not satisfy my natural tendency to perfectionism, I modestly tried to follow the admirable historical example of Ernst Abbe (1840-1905), collaborator then successor of Carl Zeiss.
This mathematician of Göttingen, within the Carl Zeiss company, revolutionized manufacture of the microscopes made before traditionnally and an empirical way, by creating his laws of geometrical optics and âmathematisingâ the design of the optical instruments.
After my 15 years of impassioned activity of Scientific advice in the Carl Zeiss Foundation, and regarding Abbe as a great example to be followed, I was convinced that a thought process of comparable nature, based on mathematics, was applicable to the field of the orthopedic implants.
1.9.2. Augustin Fresnel
This great physicist (1788 - 1827) was used to me as model during my studies at the School of Applied Optics, then in the Sorbonne with Professor Maurice Françon and finally professionally in Carl Zeiss Foundation until 1977. He created the concept of Wavelength, developed the undulatory theory of the light and the luminous interferences.
It is its principle of cutting of the large lenses in successive steps, by preserving in each step the optically functional part but by removing useless volumes of heavy glass which enabled him to build the lenses of lighthouses at levels, hundred times lighter than the cast solid lenses, of fabulous numerical opening, almost using all the light emitted by the source: the lenses of Fresnel.
I had the idea in 1990, to transpose his philosophy of logical cutting in levels, with the conical junctions used to assemble the components of the prostheses, or to fix implants in the bone. It is what gave my Junction MulticĂŽne (3.4.2.), applied in Cotyle Bicon (5.3.1.) and the prosthesis Modular (5.1.4.), object of my Patents (6.8.3. and 6.8.6.). Cutting in conical steps makes it possible to make the global form of the junction independent of the blocking angle of the cone. Cutting also makes it possible to manage the thicknesses of materials, not for questions of weight like Fresnel, but for the control of the flexibility.
1.9.3. Werner Heisenberg
Physicist and German Philosopher (1901-1976), Nobel Prize of Physics 1932 for the creation of Quantum Mechanics. It is Maurice Françon in the Sorbonne in 1964 who made known to me this physicist, for its Principle of Uncertainty, which I prefer to call Pendulum of Uncertainty. Since, I continue my reflections on the generalization of this principle to several close branches, particularly in physical and instrumental optics, in my Theory of Deconjugation, unifying and explanatory, joining together under a common comprehension twenty physical phenomena and processes.
As showed it so well the philosopher Catherine Chevalley in her analysis of the âManuscript of 1942â in which he is opposed to the national-socialism, published in 1984, Heisenberg courageously and intelligently delayed and neutralized the development of the German atomic bomb, while remaining at its position of director of the German atomic program. His friend Niels Bohr did not understand his courageous position, just as other scientists.
Nature in contemporary physics The Manuscript of 1942 The Part and the Whole 1965 Physics and Philosophy 1958
1.9.4. Antoni Gaudi
Very recently, I took note of work of the immense architect Antoni Gaudi, of Barcelona (1852 - 1926).
Independently of an incredible artistic creativity, Gaudi developed a true research program on the aspects of the geometry which could be important for its work. He concentrated on the experimental search of optimal geometrical solutions which it could apply to its projects. Curves, surfaces and transformations interested it only if it could apply them in its constructions. He created a geometrical universe on the service of its own creativity.
His thought process to support by mathematics the architectural design consolidates me in the certainty of my own step in the more modest field of the orthopedic implants.
Its surprising cathedrals and its constructions, whose stones follow the direction of the forces, will survive a long time the buildings weakened by the obsession of the vertical. Many buildings built since three millenia would be still upright, instead of being today only stone heaps.
As my achievements are thousand times smaller and thousand times less visible, only the publication of this document will be able finally to make known them.
1.10.1. How system ZweymĂŒller-SL âAlloClassicâ did occur?
In March 1984, in a big private clinic of the surroundings of Nice, I took part in the implantation of a stem of ZweymĂŒller of first generation. At that time, only sizes 10,12.5,15 and 17.5 were available. The femur was suitably prepared for the size 12.5 but during the test of stability, the overall length was insufficient and stem 15 was tested, initially without grating again. With our great surprise, stem 15 was unstable. It presented small movements in the frontal plan and several degrees of angle in the sagittal plan. In addition, the operator had me announced frequent crural pains among other patients with suspicion of instability of the stems and overload to the level of their point. As of the end of the operation, still in the carpark, I started to schematize this real clinical problem geometrically.
1.10.2. Starting of the research
Quickly, the problem appeared complex from the mathematical point of view and I began the writing of a geometrical program of description in FORTRAN language.
It appeared necessary to me to find, not only relations between the geometric standards of a size of prosthesis, but also the relations connecting dimensions of several successive sizes. It is obvious today that many prostheses without cement ended in failures because of the absence of any mathematical law.
The project required, at the time, the use of the supercomputers Control Data 6600 and then the CRAY ONE. A series of prototypes and rasps were constructed after about thirty simulations by calculation without having to construct intermediate metal prototypes. I exposed this project to Professor ZweymĂŒller in Vienna in August 1984. The experimental implantations in anatomy laboratory took place in December 1984. The analysis of the series of anatomic implantations highlighted the consequent improvement of primary fixing. The series of stems which resulted from it required since any correction.
This series called today AlloClassic was established to date on more than 1.000.000 patients.
After eight years additional research and work, in 1992, I entirely reprogrammed a new generation of stems with new mathematical formulations, other data-processing languages and other computers. It was a total recasting and not some minor modifications, as some claimed.
This second series, called SL Plus was implanted to date on more than 1.000.000 patients.
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