Instability of the proximal tibio-fibular joint.

The proximal tibio-fibular joint consists of a joint cavity surrounded by a joint capsule (diarthrosis) forming a rather rigid joint. In patients who complain of pain and instability in the knee, the cause may sometimes be found in laxity of the proximal tibio-fibular joint. In these cases the abnormal movements of the fibular head are palpable and visible and can be demonstrated on X-ray films. The disease is not well known and is often overlooked. It can be differentiated by palpating the fibular head. In two patients the pain and disability were so severe that fusion of the proximal tibio-fibular joint was undertaken. This treatment seems to have been successful.