Total knee arthroplasty in femorotibial instability.

Regarding the reasons for failure of conventional knee arthroplasty a lot of work has be done on loosening and polyethylene wear, often leading to recurrent deformation and osteolysis. But there are only few reports concerning femorotibial instability. This instability is related to failure of the collateral ligaments which can often be found in cases of important frontal deformity both in the varus and valgus knee or in rheumatoid arthritis. Femorotibial instability has been reported in the literature as reason of failure of knee replacement in 10 to 30% of all cases. This complication may be avoided by a precise preoperative analysis including unipodal standing view and stress X-Rays. Encouraged by the good long-term results published by the Endo-Klinik we started to use the ENDO-Model rotational knee system in patients with suspected femorotibial instability in order to resolve the problems of resurfacing the patella restoring mobility correcting the deformity stabilising the knee In fact, the rotating or hinge prosthesis is actually transforming the anatomical joint in a mechanical joint in which the pivot is acting as a ligament should act.