The hip prosthesis, and also that of the knee, restores a functional mobility interface by means of a pair of articular surfaces.
In North America, the pair of metal-polyethylene prosthetic surfaces is mainly used. Or, at the hip, a hollow part for the acetabulum (insert) in polyethylene, generally housed within a metal cup. The hemispherical part facing it, carried by a femoral stem and which will articulate with the restored acetabular surface, is metallic.
Europe, for its part, has preferred to favor the use of ceramic/ceramic or ceramic/polyethylene couples.
The success rates in the two continents are very comparable. The habits adopted in the United States are due to establishments in a population that is generally more likely to be overweight and also more fond of sporting activities. In this population, during initial experiments, fractures of ceramics had occurred, incidents which have now become extremely rare, but still leave some reluctance to use them.
The use of polyethylene was initially accompanied by wear over time: the debris generated produced nearby osteolysis, compromising the very strength of the prosthesis. This is why the development and introduction, more than twenty years ago, of a new highly cross-linked polyethylene, little exposed to wear phenomena, constituted a radical evolution of this surgery already endowed with an excellent reputation among the population.
The persistence, over time, of the quality of the result of this surgery necessarily remains a central objective.
Persistence of the quality of the result over time is a central objective
Cementless implantations
The use of methyl methacrylate cement allows immediate operative sealing of prosthetic parts during the procedure. However, this interface of harmonious cohabitation between the prosthesis and the skeleton proves to carry a certain fragility over time. This is why research has developed implants promoting osseointegration, that is to say without cement.
This success currently mainly concerns the hip, for which many implantations, both for the acetabulum and for the femur, manage to do without cement. This approach requires an even more meticulous and codified surgical technique, and implants even better adapted to this anatomy of bone/prosthesis symbiosis.
This adoption of “cementless” allows both a saving in operating time and greater ease of subsequent recovery, in the event of a need to change the prosthesis. It is criticized for a higher risk of fracture, due to the close fit of the prosthetic part with its receiving skeleton.
Demanding, “cementless” shortens operating time and facilitates recovery
Improved stability
The use of registers of implanted prostheses (initially introduced by the Scandinavian countries, with very centralized health insurance systems) has made it possible to bring together large databases on the fate of implanted prostheses.
For the hip, a point of vigilance persisted regarding the occurrence of dislocations: although rare, of the order of 1 to 2%, this incident nevertheless remains significant. It is more the case of posterior implantations, and/or neurological patients, and/or demuscles. The development of better stabilized prostheses, called “dual mobility”, constituted a significant advance: this French invention is now adopted throughout the world.
Less approximate covers
Whether in the short or longer term, after prosthetic surgery, it is always possible that a revision or revision surgery will be necessary, whatever the reason: loosening of the prosthesis (loss of prosthesis/skeleton solidarity), instability, mechanical defect, infection etc.
The revision consists of the implantation of a new prosthesis, after removal of the defective one. This procedure traditionally left surgical teams feeling like a compromise solution. The idea was in fact established that the “second intention” prosthesis would never achieve the technical perfection of a first intention implantation, on a virgin skeleton. This era now seems partially over; revision surgery has strived to reproduce the quality objectives of a primary implantation, either through technological devices (robotics and/or interventional assistance navigation, use of personalized implants developed in three dimensions, use of grafts and/or or bone substitutes, etc.), or through better controlled and codified surgery (better training of increasingly specialized teams).
This transformation and the optimization of the surgical methodology for prosthetic revision are both apparent in terms of hip prosthesis and knee prosthesis.
The environment of the operation
The actual management of the operated patient also constitutes a significant element of the progress made in prosthetic surgery, whether pre-, intra- or post-operatively.
From the planning of the surgical project and the preoperative anesthetic visits, protocols for information, preparation and acceleration of prosthetic joint functional recovery are put in place. Intraoperatively, in addition to the use of various locoregional anesthesias, the use of tranexamic acid has become almost systematic; through its antihemorrhagic effects, it considerably reduces blood loss during the procedure. The management and control of postoperative painful phenomena requires an entire arsenal of multimodal analgesia, including locoregional sensory nerve blocks and increasingly personalized analgesic-anti-inflammatory cocktails, making it possible to avoid opiates, which occasionally generate pain. ‘addictions.
An international industrial dynamic
We cannot conclude this overview of the numerous advances made in all directions without looking at the determinants of this dynamic. It clearly appears that it is the result of international collaboration accompanied by exchanges of scientific information, encouraged by specialized publications and/or conferences. Inventions, once confined to a given surgical school or national research institute, are spreading across the globe, often through industry, accompanied by its effective marketing. Quoting the quip of the famous North American gangster William Sutton from the 1930s, to whom the FBI asked “Why are you attacking the banks? »and who naively responded “That’s where the money is”Professor Daniel Berry underlines the favorable role of industry; the latter, focused on financial profits, offers surgeons devices constituting an innovative solution to the medical problems that concern them. The surgical community, sometimes in collaboration with industry, is always on the lookout for the elegant and simplified solution to an insufficiently resolved surgical situation. Subsequently, it is collective reflection and experience which will validate or not the industrial offer, itself derived from individual invention.
This is how French solutions emerged, subsequently disseminated throughout the world: the dual-mobility hip prosthesis, the so-called inverted shoulder prosthesis, etc.
