The effects of excessive pre-operative anterior tibial translation on post-operative knee stability after anterior cruciate ligament reconstruction

Abstract

Objective To investigate the effects of excessive pre-operative anterior tibial translation (ATT) on post-operative knee stability after anterior cruciate ligament (ACL) reconstruction. Methods From January 2016 to December 2016, a total of 348 patients with noncontact ACL injuries who underwent primary anatomic single-bundle ACL reconstruction were retrospectively analyzed. The hamstring autograft was used as the grafted tendon. The ATT relative to the lateral femoral condyle was measured on pre-operative magnetic resonance imaging (MRI) scans. Among them, twenty patients (ATT positive group) who demonstrated >10 mm ATT distance were matched in a 1∶2 fashion to 40 control participants (ATT negative group) with <3 mm ATT distance. All patients were followed for at least 2 years. The post-operative clinical outcomes, including the ATT distance, the KT-1000 side-to-side difference, and the pivot-shift tests were compared between the two groups. Results The ATT distance of the ATT positive group was 13.5±1.3 mm, which was significantly larger than that of the ATT negative group (2.5±1.4 mm) (t=45.435, P=0.013) pre-operatively. At 2-year follow-up, the ATT distance of the ATT positive group was 9.7±1.8 mm, which was significantly larger than that of the ATT negative group (0.9±1.6 mm) (t=49.655, P=0.011). Moreover, the KT-1000 side-to-side difference of the ATT positive group was 4.4±1.5 mm, which was also significantly larger than that of the ATT negative group (0.8±1.1 mm) (t=38.945, P=0.014). There was significantly difference in the pivot-shift test between the two groups (ATT positive group: 1 grade 0, 18 grade I, 1 grade II vs. ATT negative group: 39 grade 0, 1 grade I) (χ2=40.521, P=0.012). Conclusion Excessive ATT could not be completely restored to normal after isolated anatomic single-bundle ACL reconstruction. Compared to the ATT negative group, the ATT positive group has inferior knee stability at 2-year follow-up. Key words: Anterior cruciate ligament reconstruction; Wounds and injuries; Joint instability