Abstract: A semiconstrained prosthetic knee for surgical replacement of a dysfunctional knee includes a tibial platform, a movable bearing element, and a femoral component. The femoral and tibial components are typically constructed of a cobalt-chromium alloy and each includes an extension for securing the component to the bone. The femoral component includes a polycentric convex bearing which slidably engages a movable bearing, typically constructed of high molecular weight polyethylene. The superior surface of the bearing element is designed to congruently slidably engage the inferior surface of the bearing portion of the femoral component throughout the flexion/extension range of the knee. The inferior surface of the femoral component is generally convex with two or more offset portions of varying radii of curvature matching complimentary superior surfaces of the bearing element. The inferior surface of the femoral component may have more than one radii of curvature at different points along the convex surface.