Risk factors for knee instability after anterior cruciate ligament reconstruction

Purpose The objective of this study was to estimate risk factors that influence postoperative instability after anterior cruciate ligament (ACL) reconstruction using multivariate logistic regression analysis. Methods A total of 152 consecutive patients with symptomatic ACL insufficiency underwent arthroscopic ACL reconstruction between 2005 and 2011. Loss to follow-up and previous ligament reconstruction were exclusion criteria, resulting in 131 patients remaining for this retrospective study. The median follow-up was 55 months (range 25–100 months). Patients were sorted into two groups by anterior translation on stress radiograph and pivot shift test grade and were analysed for the statistical significance of various risk factors including age at surgery, gender, body mass index, preoperative instability, time from injury to surgery, single-bundle reconstruction with preserved abundant remnant versus double-bundle reconstruction with scanty remnant, and concomitant ligament, meniscus, and articular cartilage injury with use of multivariate logistic regression analysis. Results Time from injury to surgery over 12 weeks was found to be a significant risk factor for postoperative instability [ p