Joint Space of the Human Knee and Hip Joint under a Static Load

Abstract
In order to study the joint contact and joint space of statically loaded human knee and hip joints, observations of serial slices of joint specimens which were frozen during the application of a load were carried out. In the intact joints, the articular cartilage surfaces did not come into direct contact with each other even under a load of more than twice that of the body weight. The minimum distance between cartilage surfaces in each specimen ranged from 0.2 to 0.6 mm. The Indian ink which was injected into the joints before the load application was squeezed out of some areas of the remaining joint space, but a dye-free fluid apparently remained in this space. Based on our findings, the definition of joint contact and the lubrication mechanism in the intact human joint have been discussed.