Risk factors for prosthetic hip and knee infections according to arthroplasty site.

Prosthetic joint infection is a devastating complication of arthroplasty. Previous epidemiological studies have assessed factors associated with arthroplasty infections but have not assessed the impact of comorbidity on infection at different arthroplasty locations. We used a case-control design to investigate risk factors for prosthetic joint infection with reference to the anatomical site. During an eight-year period at a single hospital, 63 patients developed a prosthetic joint infection (36 hips, 27 knees). Cases of prosthetic hip or knee joint infection were matched 1:2 to controls. The results suggest that factors associated with arthroplasty infections differ with anatomical location. Following knee arthroplasty, wound discharge was associated with an increased risk of prosthetic joint infection whereas the presence of a drain tube reduced the risk. By contrast, increased body mass index, increased drain tube loss and superficial incisional surgical site infections (SSIs) were associated with prosthetic hip infection. When analysed as a combined cohort, systemic steroid use, increased SSI drain tube losses, wound discharge, and superficial incisional SSIs were predictors of infection.