Muscle performance after anterior cruciate ligament reconstruction.

We measured muscle strength in 36 patients after anterior cruciate ligament (ACL) reconstruction with autogenous bone-patellar tendon-bone graft. Quadriceps and hamstring isokinetic strength was assessed during concentric contraction at 60 and 180 degrees /s and was measured at 1, 6, 12 and 24 months postoperatively. At 24 months quadriceps muscle strength had recovered to approximately 90% of the level of the uninvolved side, both at 60 and 180 degrees /s. In contrast, hamstring muscle strength had already recovered to approximately 90% at 6 months. Age, gender, activity level, and anterior tibial laxity did not affect the muscle performance. However, the recovery of muscle strength was delayed in patients with anterior knee pain.