Intérêt de la personnalisation des implants dans la prothétique du genou

The use of imaging technology, such as 3D scanners, has allowed us to better inform ourselves about the anatomical variability of knee shapes and lower limb alignments in different populations and their possible impact on clinical outcomes after total knee arthroplasty. This large variability of knee phenotypes is both dimensional and functional because not only the size or proportions, but also the shape and orientation of the articular surfaces vary and therefore impact joint function in its mobility or dynamic performance. One of the objectives is to be able to deduce from the CT images of the arthritic knee, the pre- arthritic shape and alignment to propose an individualized solution for knee reconstruction. At the implant level, the approach consists of geometrically decoupling the trochlear shape from the condylar shape, but also of replicating the sagittal condylar curvatures and the distal femoral interline and finally of adjusting the medial and lateral dimensions, which are often asymmetrical. In terms of lower limb alignment, an orientation of the mechanical axis up to 5° of varus or 3° of constitutional valgus is tolerated but limited according to a planning matrix. An individualized prosthesis also requires a critical look at the normality of the shape to be reproduced to guarantee effective knee kinematics. It also requires perfect reproduction of the preoperative planning and must therefore be accompanied by individualized implantation instruments.