Kinesiology of the knee joint. An experimental investigation of the ligamentous and capsular restraints preventing knee instability

Abstract

The purpose of this study was to elucidate the function of the ligamentous and posterior capsular structures of the knee joint and the types of instability that may be caused by lesions to these structures. Despite the use of complicated technical appliances and the defined, uniform conditions, the investigators in measuring the mobility in the knee joint have usually arrived at divergent results. Often, the manner of measuring the various movements has not been mentioned, or the moment or force applied to the knee joint were not well-defined, or else the instability was recorded at only a few positions during the extension-flexion movement of the knee. A measuring apparatus was devised which allows continuous registration, accurately, and in a reproducible manner, of the valgus-varus, axial rotatory, and translatory instability in the extension-flexion movement of the knee during application of a well-defined, constant moment or force to the knee joint. A lever, fitted with strain gauges and connected to three potentiometers, was fixed to the tibia. The lever was moved manually in a way so that during a "circumduction" of the lever, the moment was constant in the valgus, varus, internal or external axial rotation direction. Likewise, the anteriorly or posteriorly directed force was constant. Anterior-posterior tibial displacement was measured by two sliding potentiometers. By means of a computer the resulting movement could be plotted in the form of mobility patterns. Patterns were plotted partly with intact ligaments and partly after isolated and various combinations of transection of the collateral ligaments, the posterior capsule, the cruciate ligaments, and the popliteal tendon. A total of 115 preparations were investigated in this manner.