Knee analyser: An objective method of evaluating mediolateral stability in the knee

Abstract

A machine is described which is capable of accurately determining the mechanical behaviour of the knee as it undergoes mediolateral bending under controlled conditions. This knee analyser applies a constant valgus and varus angular deflection rate to the knee up to a preset moment limit. The applied moment is sensed by a strain-gauged pillar and the angular deflection by a precision potentiometer. The resulting voltages are fed to an xy recorder yielding a plot of moment against angle. By monitoring distraction of the joint concurrently, the deformation characteristics of ligament and cartilage components can be evaluated. The machine should assist in the diagnosis of knee problems, follow-up of patients with rheumatoid arthritis, evaluation of operative procedures on the knee and should also provide fundamental information on the properties necessary for future knee replacements.