An analysis of the causes of deep infection after hip and knee arthroplasties.

Infection is a dreaded complication of joint arthroplasty. Deep infection may arise by contamination during operation, by secondary contamination of a discharging hematoma during the post-operative phase, or by the hematogenous route. Sixteen suspected cases of early and late deep infection in 1500 primary hip and knee arthroplasties performed during a ten-year period are reviewed. The operations were all performed by one of the authors (J.M.S.) in a Charnley Howarth sterile-air enclosure. No prophylactic antibiotic therapy was used, and the minimum follow-up period in all patients was one year. Suspected causes of infection were noted in six patients: the infection was considered to be hematogenous in three and to result from hematomas in two, and in the sixth patient a suspected rheumatoid cyst may have been a Brodie's abscess. Ten patients had no apparent predisposing source of infection, and breach of sterility technique was the most likely cause of infection in this group. Only two patients have required revision surgery to date. Although hematogenous infection of joint arthroplasty is possible, early, intermediate, or late infections generally are introduced during surgery either from the air or by direct contamination.