No association between positive intraoperative allograft cultures and infection rates after reconstructive knee ligament surgery

Abstract

Background: Several reports of severe infections associated with allograft tissue in knee reconstructivesurgery have led many surgeons to consider routine intraoperative culture of allograft tissue before implantation. Thus, the purpose of this study was to determine the prevalence of positive soft tissue allograft cultures in reconstructive knee surgery, and evaluate its association with surgical site infection. Methods: Retrospective study of 202 patients who underwent knee reconstructive ligament surgeries, including revisions, between January 2013 and July 2017. Intraoperative culture results were obtained and the report of a surgical site infection during follow-up was recorded. Patients without cultures were excluded. A priori power analysis was performed. The association between positive culture results and development of surgical site infection was evaluated usingFisher's Exact test (P b 0.05). Results: A total of 300 allografts were implanted in 202 patients. Mean average follow-up was 32.9 ± 12.5 (range 13 to 57.9) months. Sixteen patients had positive intraoperative allograft cultures (7.9%). The most frequently isolated organism was Bacillus species (six cultures); none of these patients presented with clinical signs of infection. Nine patients developed surgical site infections and were treated with oral antibiotics, and one patient developed septic arthritis that required surgical debridement of the implanted graft; all of these patients had a negative soft tissue allograft culture. No significant association was found between a positive culture and surgical site infection (P= 0.43). Conclusion: There was no apparent association between positive intraoperative irradiated soft tissue allograft cultures and surgical site infection in reconstructive knee surgery.