Risk factors for primary anterior cruciate ligament reconstruction failure

Objective To explore the risk factors of primary anterior cruciate ligament (ACL) reconstruction failure. Methods From November 2015 to May 2017, a total of 178 consecutive patients with clinically diagnosed non-contact ACL injury were treated and followed-up more than 2 years. Twenty-five patients (post-operative failure group) who underwent completely ruptured ACL graft confirmed by MRI, positive pivot-shift test, more than 5 mm side-to-side difference (SSD) measured by KT-1000 arthrometer, more than 5 mm static anterior tibial translation (ATT) measured on MRI were determined to be ACL reconstruction failure. They were matched in a 1∶2 fashion to 50 non-failure patients (post-operative non-failure group), who showed intact ACL graft 2 years after ACL reconstruction. The sex, age, body mass index (BMI), affected side, meniscal injury side, time from injury to surgery, KT-1000 SSD, pivot shift test under anesthesia, follow-up duration, posterior tibial slope (PTS) and ATT measured on the pre-operative weight-bearing whole leg radiographs between the two groups were compared using univariate analysis. Moreover, the predictors of ACL reconstruction failure were assessed by multivariable conditional Logistic regression analysis. Results Post-operative failure group had a significantly higher PTS and ATT values than those in the post-operative non-failure group (17.21°±2.20° vs 14.36°±2.72°, t=4.395, P 0.05). Multivariable Logistic regressions indicated that PTS≥17° (OR=15.62, P=0.002) and ATT≥6 mm (OR=9.91, P=0.006) were independent risk factors for primary ACL reconstruction failure. However, sex, age, BMI, meniscal lesions, degree of pivot shift test, KT-1000 SSD were not the independent risk factors. Conclusion PTS≥17° and ATT≥6 mm could increase the risk of primary ACL reconstruction failure. Key words: Anterior cruciate ligament reconstruction; Treatment failure; Risk factors