ON THE USE OF A CONSTANT RADIUS FEMORAL COMPONENT IN MENISCAL BEARINGKNEE REPLACEMENT

Kinematic and clinical evaluation of a constant radius of curvature fe moral component (Oxford knee) and one with a decreasing radius of curv ature (LCS knee) favors the use of a femoral component with decreasing radius of curvature. Constant radius of curvature femoral components tend to move excessively in the posterior direction under load bearing and can increase the incidence of subluxation or dislocation of uncon strained meniscal bearings. Additionally, constant radius femoral comp onents increase the stretch on collateral ligaments which inhibits fle xion. They also create edge loading of the bearing at surface runout. Decreasing radius of curvature femoral components maintain more centra l positioning of meniscal bearings and allow natural collateral ligame nt tension to prevent bearing dislocations and allow normal flexion, e ven in the absence of the anterior cruciate. Properly designed decreas ing radius of curvature femoral components have demonstrated exception al wear and dislocation resistance over a 16-year interval.