Design of Knee Prostheses for Bone Loss and Instability

Abstract

Experience has shown that most cases requiring knee implants can be dealt with by the standard condylar designs, with or without cruciate ligament retention. Preoperative instability can be overcome by a combination of ligament releases and tightening of the joint by appropriate component thicknesses. Correct alignment in the frontal plane is an important aspect in restoring stability in ensuring that the foot-to-ground reaction force normally passes through the knee. However, even correct alignment does not substitute for lack of collateral ligaments because the foot-to-ground force vector will sometimes pass outside of the joint [1] leading to varus-valgus instability.