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Septic Arthritis After ACL Reconstruction: Does Graft Retention Portend Increased Risk of Surgical Revision?

      Introduction

      The purpose of this study was to evaluate the clinical and functional outcomes of patients with septic arthritis after ACL reconstruction with and without graft retention.

      Methods

      A retrospective query of the Military Health System Management and Reporting Tool was performed to identify all patients undergoing primary arthroscopic ACL reconstruction with subsequent development of septic arthritis between 2007-2013. Clinical course, objective physical exam findings, and patient-reported outcomes were recorded. Graft choice, time to treatment, bacterial culture and specificity, number of arthroscopic debridements, and graft retention were evaluated as potential risk factors. Primary outcomes of interest included persistent ACL laxity (i.e. Lachman test of 2+ or greater or positive pivot shift), revision ACL reconstruction, and inability to return to military function.

      Results

      31 patients were isolated at a mean follow-up of 24-months. Graft choice included hamstring autograft(55%;n=17), hamstring allograft(32%;n=10), and autologous bone-patellar tendon-bone (13%;n=4). A total of 8 patients(26%) developed an acute infection (<2 weeks), 17 patients(55%) had subacute infection(2-6 weeks) and 6 patients(19%) had chronic infection(>6 weeks). The most frequently isolated bacteria were MRSA(35%;n=11), MSSA(n=2;6.5%) and MRSE (n=2; 6.5%), whereas 15 cases(48%) had no known isolate. All patients were treated with arthroscopic debridement(average 2.3;range,1-4) and intravenous antibiotics, and the graft was retained in 64%(n=20). Of this group with graft retention, 6 patients developed significant knee laxity (30%) and 2 of these underwent revision(10%). Two patients each with subacute and chronic infections developed early post-infectious arthritis, as compared to no patients with acute infections. In this study 48%(n=15) were able to return to military function, and there was no statistically significant difference according to graft retention.

      Conclusion

      Arthroscopic irrigation and debridement with graft retention is an effective treatment for patients with septic arthritis after primary ACL reconstruction. Factors affecting clinical outcomes may include late presentation and residual graft laxity after arthroscopic irrigation and debridement.