Department of Orthopaedic Surgery, Mayo Clinic, Rochester Mn, United States

Orthopaedic Surgery, Mayo Clinic, Rochester, Minnesota, United States

Purpose: There is little information available to guide clinical decision making in the diagnosis of indolent infection in patients undergoing revision elbow arthroplasty. The purpose of this study was to review the preoperative and intraoperative investigations of patients who underwent revision elbow arthroplasty and had unexpected positive intraoperative cultures at the time of revision surgery.

Material and Methods: Between 2000 and 2007, 236 consecutive total elbow arthroplasties underwent revision surgery at our institution. There was no evidence of infection in 194 elbows (Group A). Overt signs of infection were present preoperatively in 20 elbows (Group B). In 22 of the remaining 216 elbows (10.2%), there were no overt signs of infection but intraoperative cultures were positive (Group C). Perioperative testing included CBC, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), radiographs, selective preoperative aspiration, and intraoperative histologic analysis.

Results: The mean white cell count was 7.0 in Group A, 7.5 in Group B, and 6.9 in Group C. The mean ESR was 17.6, 31.9 and 20.6 for each group, and the mean CRP was 1.4, 6.6 and 2.2 respectively. In Group C, histologic evidence of infection was present in 2 cases (9.1%) and radiographic signs of loosening in 19 cases (86.4%). Antibiotic therapy was initiated in 13 patients (59.1%) in Group C, whereas in the remaining 9 (40.9%), the positive cultures were considered contaminants and were not treated. At latest follow-up, 18 elbows (81.8%) in Group C remained well fixed with no signs of infection. With the numbers available, there were no differences in Group C between elbows treated and not treated with antibiotics.

Conclusion: Positive intraoperative cultures may be expected in approximately 10% of failed elbow arthroplasties with no overt signs of infection. Perioperative testing has limited value in detecting patients who will have positive cultures at the time of surgery. The clinical significance of positive intraoperative cultures in the absence of overt signs of infection remains under investigation.