Partial rupture of the anterior cruciate ligament. Natural course.

A prospective study was done of 29 patients with conservatively treated partial ruptures of the anterior cruciate ligament that were stable at the initial examination under anesthesia. The ruptures were reevaluated for stability and knee function from 12 to 60 months after injury. Many had developed signs of instability. The forward drawer sign (Lachman test) and the pivot shift tests were positive. There was also measurable sagittal instability (anterior drawer sign). In every case, knee function was almost completely restored.