Postoperative Infections After Anterior Cruciate Ligament Reconstruction Significantly Increase the Risk of 3-Compartment Osteoarthritis at Long-Term Follow-Up.

PURPOSE: To compare the long-term radiographic and clinical outcomes of patients who developed postoperative infection after anterior cruciate ligament reconstruction (ACLR) with those of a matched cohort of patients who underwent uncomplicated ACLR to determine the impact of infection on the development of osteoarthritis (OA) and knee function. METHODS: This retrospective case-controlled comparative study included patients who developed postoperative infection after primary ACLR performed between January 2003 and January 2014. Eligible patients had no baseline OA and a minimum 10-year clinical and radiographic follow-up. A matched group of patients with uncomplicated ACLR served as controls. Radiographic OA was assessed using the Kellgren-Lawrence and Osteoarthritis Research Society International criteria, alignment with the hip-knee-ankle angle, and clinical outcomes with the International Knee Documentation Committee, Lysholm, and Tegner scores and KT-1000 anteroposterior laxity. Statistical comparisons were performed using independent t-tests for continuous variables and Fisher's exact test for categorical outcomes. RESULTS: At a mean follow-up of 16.2 years (range, 14-19 years), all 7 patients who developed postoperative infection showed 3-compartment OA (Kellgren-Lawrence grade ≥2), whereas 35% of the control group developed OA (P = .0058). The hip-knee-ankle angle averaged 4.42° varus in infected knees versus 4.67° varus in control knees (P = .77). No significant differences were observed in clinical scores, anteroposterior laxity, or contralateral knees between groups. CONCLUSIONS: This study shows that postoperative infection after ACLR significantly increases the risk of 3-compartment OA at long-term follow-up compared with uncomplicated ACLR. LEVEL OF EVIDENCE: Level III, retrospective comparative study.