Sagittal knee stability after anterior cruciate ligament reconstruction with a patellar tendon strip. A two-year follow-up study.

Tibial anteroposterior displacement after anterior cruciate ligament reconstruction with a patellar tendon graft was followed prospectively for 2 years in 24 patients with an arthrometer. The femoral ligament insertion location, in a lateral projection, and the change in intraarticular fixation distance, measured with an isometer, were documented intraoperatively. Two years after surgery, the overall mean injured-noninjured difference in anteroposterior displacement was 2.0 +/- 2.3 mm. All grafts were fixed during surgery at 20 degrees of knee flexion. Patients for whom this angle coincided with the angle of minimum intraarticular fixation distance (Group I), and patients who had a femoral ligament insertion location > 2 mm anterior to the center of the normal anterior cruciate ligament attachment (Group A) showed larger tibial displacement than the other patients. An injured-noninjured difference in tibial anteroposterior displacement > or = 3 mm was classified as failure. Groups I and A failure rates were higher than for the other patients. No correlation was found between anteroposterior displacement and magnitude of the change in intraarticular fixation distance. We conclude that anterior femoral locations lead to larger sagittal play after 2 years than central or posterior locations and that the magnitude of the fixation distance is less important than the pattern.