Effects of pre-operative knee laxity on clinical outcomes after partial anterior cruciate ligament reconstruction.

BACKGROUND: The effects of retaining residual bundles on surgical outcomes has not been observed, so we evaluated the effects of preoperative knee laxity on clinical outcomes after partial anterior cruciate ligament (ACL) reconstruction for partial ACL rupture in this study.

PURPOSE: To evaluate the effects of preoperative knee laxity on clinical outcomes after partial anterior cruciate ligament (ACL) reconstruction for partial ACL rupture.

METHODS: The data of 47 patients, who had partial ACL rupture and underwent partial ACL reconstruction, were retrospectively analyzed. According to preoperative kneelax arthrometer and pivot shift test, the 47 patients were divided into group A (kneelax arthrometer ≤5mm and pivot shift test <II grade, n=26) and group B (kneelax arthrometer >5mm and/or pivot shift test ≥II grade, n=21). The minimum follow-up duration lasted 2 years. The clinical outcomes were evaluated using IKDC (International Knee Documentation Committee) scoring systems, Lysholm knee scoring scale, Tegner activity rating, Lachman test, Pivot shift test and the kneelax arthrometer.

RESULTS: The function and stability examinations for the affected knee joint were significantly improved in both groups after partial ACL reconstruction as compared with preoperative ones (all P<0.01). There were no significant differences in the post-operative Lysholm and Tegner scores, Lachman and Pivot shift test results between both groups (all P>0.05). However, there were significant differences between the two groups in terms of the post-operative IKDC scoring system and kneelax arthrometer examination result (all P<0.05).

CONCLUSIONS: In the patients with partial ACL rupture, the mechanical strength of the remnant ligament has significant influence on the therapeutic effects of partial reconstruction. The patients with kneelax arthrometer >5mm and/or pivot shift test ≥II grade still have anterior instability in the affected knee after partial reconstruction.