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

Matching resulted in 17 patients per group. While the patient-reported outcome measures (PROMs) (IKDC, Tegner, Marx and SF-12) showed no significant differences between the groups (p > 0.05), the WOMAC score was significantly worse in the infection group (p = 0.016). Range of motion deficits were more frequent in the infection group (65% vs. 18%; p = 0.005). The infection group also had higher Kellgren-Lawrence grades (2 [1-2.75] vs. 0 [0-1], p < 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.