Do anterior cruciate ligament allograft culture results correlate with clinical infections?

PURPOSE In 1998, four cases of contaminated allografts for anterior cruciate ligament (ACL) reconstruction resulted in Clostridium infection, and a patient with Clostridium infection from a femoral condylar allograft died. It was subsequently published that implanting surgeons should culture ACL allografts so that action could be taken should highly pathogenic bacteria be encountered. The purpose of this study is to test the hypothesis that ACL allograft cultures correlate with clinical infections. METHODS Since October 2003, a single surgeon performing ACL reconstruction prospectively cultured all allografts in the operating room before implantation. After culture, grafts were thawed in warm saline mixed with bacitracin. All patients received a single dose of preoperative antibiotics. Final culture results were obtained in all patients, and all patients were followed for a minimum of 90 days to evaluate for postoperative infection. The cost of cultures was determined by multiplying hospital charges by the hospital cost-to-charges ratio. RESULTS Two hundred and ten cases were included. Ten allografts (4.8%) had positive culture results (6 coagulase-negative Staphylococci, 1 alpha-Streptococcus-not-group-B, 1 Enterobacter, 1 Clostridium, and 1 polymicrobial [Klebsiella, Escherichia coli, and Enterococcus]). None of these patients had signs of infection; the three positive highly pathogenic bacteria (Enterobacter, Clostridium, and polymicrobial) graft recipients were treated with antibiotics. The others were observed. One patient with negative cultures developed Staphylococcus aureus infection. Mean culture cost was $127 (USD). CONCLUSIONS Our results demonstrate that ACL allograft cultures do not correlate with clinical infections. LEVEL OF EVIDENCE Level I, diagnostic study (testing of previously developed diagnostic criteria [culture]) in a series of consecutive patients (with universally applied reference gold standard [clinical evaluation for knee sepsis]).