Should draining wounds and sinuses associated with hip and knee arthroplasties be cultured?

We assessed the utility of culturing draining wounds or sinuses in evaluating periprosthetic joint infection (PJI). Fifty-five patients with a draining wound or sinus after total joint arthroplasty (28 knees, 27 hips) who had not received antibiotics for at least two weeks were prospectively studied. Superficial wound cultures were compared to intra-articular cultures to determine accuracy in isolating infecting organism(s). The superficial cultures were concordant with deep cultures in 26 of 55 cases (47.3%) and were more likely to generate polymicrobial results (27.3% vs. 10.9%; P=0.023). In 23 cases (41.8%), the superficial cultures would have led to a change in antibiotic regimen. Superficial cultures yielded bacterial growth in 8 of the 10 cases (80%) when deep cultures and further work-up suggested the absence of deep infection. Given the potential to misguide diagnosis and treatment, we recommend against obtainment of superficial cultures in patients with a draining wound or sinus following hip or knee arthroplasty.