[New method of describing the motion of the knee joint].
Knee motion in the full flexion range was measured for fourteen specimens under moderate load, and for eight normal volunteers while descending a step. Measurements showed that the posterior femoral condyles could be accurately modelled as parts of spheres. The line joining the centers of the spheres was defined as the femoral axis and joint motion was described by motion of this axis relative to axes defined on the tibial surface. From 0 to 120 degrees of flexion, the lateral center moved posteriorly by seventeen millimeters, the medical center moved forward by two millimeters, external rotation was 20 degrees, and varus-valgus rotation was 4 degrees. Specimens and volunteers gave similar results. The method was simple and accurate and has several potential applications.
D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D008722:Methods; D009038:Motion; D011859:Radiography; D012399:Rotation