Isokinetic thigh muscle performance after long-term recovery from patellardislocation

Eighty-two patients (50 women, 32 men) underwent isokinetic muscle testing on average 13 years after a conservatively treated unilateral primary patel lar dislocation. Three study groups were formed according to the natural hi story of recovery: group A (n = 32), patients with only primary conservativ e treatment; group B (n = 34) patients with conservative (group B1; n = 24) or surgical (group B2; n = 10) treatment of redislocations; group C (n = 1 6) patients with other residual complaints (anterior knee, pain subluxation s) requiring surgery. The Cybex 6000 dynamometer system was used as the res ting machine for quadriceps and hamstrings muscles, with proportional defic its of peak torque as the test parameter. Isokinetic testing revealed both quadriceps and hamstring muscle atrophy even after long-ten recovery from i njury. There were statistically significant differences between the three s tudy groups at both tested speeds of quadriceps muscles (60 rad/s, P < 0.00 2; 180 rad/s, P < 0.009). Groups BI and B2 presented similar results. The m uscle performance findings are probably due to more than one factor: primar y immobilization, poor outcome, patellofemoral degeneration, redislocations , and residual knee complaints followed by surgery and deficiency in motor control of thigh muscle had - together or separately - an effect on muscle performance.