[Causes of failure in arthroscopic anterior cruciate ligament reconstruction and outcomes of revision surgery].

Objective: To investigate the causes of failure following arthroscopic anterior cruciate ligament (ACL) reconstruction and to evaluate the outcomes of revision surgery. Methods: A total of 102 patients who underwent revision surgery due to failed ACL reconstruction between January 2017 and December 2022 at Shengjing Hospital of China Medical University were included in this study. All the patients included in the study underwent single-bundle, stage Ⅰ arthroscopic revision ACL reconstruction. Knee function was evaluated using the International Knee Documentation Committee (IKDC) score, Tegner activity scale, Lysholm score, and knee laxity. These parameters were assessed preoperatively and postoperatively at 6, 12, 18, 24, and 30 months to compare the clinical outcomes. Results: Among the patients, there were 70 males and 32 females, with a mean age of (33.2±3.6) years. The primary cause of ACL reconstruction failure was abnormal bone tunnel placement, observed in 56 cases (54.9%). Additionally, 37 failures (36.3%) were attributed to secondary trauma postoperatively, 8 cases (7.8%) resulted from graft fixation failure, and 1 case (1.0%) was due to graft disappearance caused by rejection. Medial compartment cartilage damage was the most frequently observed intraarticular lesion (35 cases, 34.3%). The mean follow-up duration was (26.8±4.0) months. At 6 months post-revision, no significant improvements were observed in IKDC or Tegner scores [(37.3±3.2) vs (36.3±5.8) points, (4.0±0.4) vs (4.0±0.7) points, respectively, both P>0.05], whereas the Lysholm score improved from (56.2±7.2) points to (83.2±4.1) points (P<0.001), and the KT-3000 side-to-side difference at 30° of knee flexion decreased from (6.6±1.3) mm to (2.3±0.2) mm (P<0.001) when compared with those before the revision operation. From 12 months onward, all functional scores and stability parameters continued to improve. At the final follow-up, the IKDC, Lysholm, and Tegner scores reached (82.2±3.3), (87.2±3.5) and (7.2±2.3) points, respectively, while the KT-3000 difference at 30° and 90° flexion was (2.2±0.7) mm and (1.8±0.5) mm, respectively; all showing significant improvement when compared with those preoperative values (all P<0.001). Conclusions: Malpositioned bone tunnels represent the leading cause of failure after arthroscopic ACL reconstruction. Revision surgery significantly improves knee function and stability during follow-up.