Post‐operative septic arthritis after anterior cruciate ligament reconstruction results in higher osteoarthritis severity and deficit of range of motion: A matched control analysis with a minimum 8‐year follow‐up

Purpose: Evaluating knee joint function, activity level, and osteoarthritis severity in patients at least 8 years after post-operative knee septic arthritis (SA) following anterior cruciate ligament reconstruction (ACLR). Methods: From May 2010 to January 2012, 39 patients at our institution were treated for knee SA following ACLR using graft-retaining treatment protocols. Follow-up examinations after a minimum of 8 years included clinical examination, measurement of anterior tibial translation (rolimeter), International Knee Documentation Committee Subjective Knee Form (IKDC), 12-Item Short Form Health Survey (SF-12), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Marx and Tegner scores. Osteoarthritis severity was described on radiographs using the Kellgren-Lawrence scale. Synovial fluid was aspirated from patients with persistent infection signs and evaluated using multiplex polymerase chain reaction (PCR). Based on ACLR graft, sex and preoperative Tegner score (±1), a 1:1 propensity score matched control group including patients with ACLR without knee SA signs was assembled. Results: < 0.001). Multiplex PCR detected no persistent infection. Two patients (10%) in the infection group required graft removal. No correlation was found between the number of lavages and long-term outcomes. Conclusions: SA after ACLR, when treated with a standardized graft-retaining protocol, results in higher OA severity, worse WOMAC scores and persistent range of motion limitations at long-term follow-up, while other PROMs and activity level remained comparable to those of non-infected cases. Level of Evidence: Level III.