Disability in anterior cruciate ligament insufficiency. An analysis of 19 untreated patients.

We analyzed the knee function in 19 consecutive patients with chronic instability after an anterior cruciate ligament rupture. Muscle strength, standing balance, activity level, functional knee score, and a performance test were evaluated. Reduced quadriceps muscle strength compared with the noninjured limb was associated with reduced performance as measured by the one-leg hop test and the Lysholm knee score. No weakness in the hamstrings was found. The patients had impaired standing balance with increased body sway in the frontal plane when standing on both the injured and noninjured limb.