A Microcomputer based system for the quantitative analysis of knee stability

A microcomputer based system for the assessment of knee stability is presented. The system consists of a seating and mechanical setup and a microcomputer-based data acquisition and data analysis system. The leg under investigation is firmly clamped at the thigh, femoral condyles and foot and malleoli, with load being applied manually to perform anterior- posterior drawer sign test, valgus-varus rotation test and internal-external tibial torsion test. The microcomputer acquires the load and displacement data from corresponding transducers placed at appropriate positions. A load versus linear displacement (or torque versus angular displacement) curve, which is in the form of a hysteresis loop, is displayed by the microcomputer in real time. Data can be stored in ASCII format for later analysis. Knee stability parametrs-total laxity and stiffness-can be calculated from the hysteresis loop.