BIOMECHANICAL CONSIDERATIONS IN PATELLOFEMORAL JOINT REHABILITATION

Patellofemoral joint biomechanics during leg press and leg extension e xercises were compared in 20 normal subjects (10 men, 10 women) aged 1 8 to 45 years. Knee moment, patellofemoral joint reaction force, and p atellofemoral joint stress were calculated for each subject at four kn ee flexion angles (0-degrees, 30-degrees, 60-degrees, and 90-degrees) during leg press and leg extension exercises. All three parameters (kn ee moment, patellofemoral joint reaction force, and patellofemoral joi nt stress) were significantly greater in leg extension exercise than l eg press exercise at 0-degrees and 30-degrees of knee flexion (P < 0.0 01). At 60-degrees and 90-degrees of knee flexion, all three parameter s were significantly greater in leg press exercise than leg extension exercise (P < 0.001). Patellofemoral joint stresses for leg press and leg extension exercises intersected at 48-degrees of knee flexion. Thi s study demonstrates that patients with patellofemoral joint arthritis may tolerate rehabilitation with leg press exercise better than with leg extension exercise in functional ranges of motion because of lower patellofemoral joint stresses.