Knee laxity and function after conservative treatment of anterior cruciate ligament injuries. A prospective study.

Knee laxity and function were investigated in a prospective study including 40 patients with acute anterior cruciate ligament injury and 11 patients with minor knee injury not involving the cruciate ligaments (controls). None of the patients had primary ligament repair. Instrumental testing (OSI, Hayward, California) of the static laxity of both knees was performed at one, three, six, and 12 months after the injury. The initial laxity of the anterior cruciate-deficient knees was greater than that of the controls. At 12 months the laxity at 180N tibial load for the patients with anterior cruciate ligament injury exceeded the laxity found within one month of injury. At 12 months half of these patients complained of symptoms of instability and one out of four patients had had severe subluxations with accompanying haemarthrosis. Patients with combined anterior cruciate and medial collateral ligament injury had the greatest initial laxity and the worst outcome. In all, 20% of the patients were scheduled for reconstruction of the anterior cruciate ligament during the observation period.