Dynamic muscle function in human normal, pathological and prosthetic knee joints

Dynamic muscle function was studied in human normal, pathological (rheumatoid arthritic, post-meniscectomy) and prosthetic knee joints. Function in the knee extensor and flexor muscles was defined from data derived from evaluations of joint motion, strength and electromyographic activity. Strength was measured during maximal voluntary isokinetic knee extension and flexion movements (torque-angle curves) at 30(DEGREES)/s, 90(DEGREES)/s, and 180(DEGREES)/s. Electromyograms (surface electrodes, rectified, time averaged) were recorded from five muscles of the lower extremity during knee movements in activities: gait, stair ascent and descent and chair rising and sitting. Analysis of the electromyographic activity emphasized the pattern, relative amplitude and coordination of activation in the different muscles. Using these methods of evaluation, characteristic deviations in functional dynamic capacity in the knee extensor and flexor muscles were described for the three patient groups. These data are applicable to the optimization of therapeutic approaches and to the improvement of prosthetic design