Knee anatomy and biomechanics and its relevance to knee replacement

Abstract

From the late 1960s to the early 1990s, when much of the original design work on knee replacement prostheses was carried out, the kinematics of the knee were universally understood to involve a rigid 4-bar link mechanism. It was understood that as the knee flexed, this mechanism caused both femoral condyles to roll back across the top of the tibia and then to roll forward with extension. Because this was thought to be a normal feature of knee flexion/extension, tibial components were made relatively unconstrained anteroposteriorly, thus permitting “roll back/forward.” The concept of the 4-bar link mechanism originated with the work of Zuppinger [1]. The concept became part of received orthopedic knowledge, perhaps as a consequence of its appearance in a number of widely used textbooks.