Predictors of wound infection in hip and knee joint replacement: results from a 20 year surveillance program

Deep wound infection (DWI) in total knee (TKA) and total hip (THA) arthroplasty has been shown to highly correlate with superficial surgical site infection (SSSI). Although several studies have reported hospital factors that predispose to SSSI, patient factors have not been clearly elucidated.

All patients undergoing TKA (n = 1181) and THA (n = 1124) surgery during the period 1977-1995 at our institution were observed at the end of a 30-day post-operative period. Thirty-three patients that developed SSSI during this period constituted the study group. The control group was composed of 64 matched subjects that did not develop SSSI. A chart review was applied to abstract DWI cases during the first 18 post-operative months for the study group and for an average of 6.7 years for the control group (range 5-18.2 years). Potential risk factors for SSSI were used as predictors of SSSI in a logistic regression analysis.

During the 18-month observation period 19 out of the 33 study subjects (58%) developed DWI. No DWI was registered in the control group (the difference was significant, p < 0.0001). Of the nine pre-operative, five intra-operative, and five postoperative factors examined, only hematoma formation (odds ratio = 11.8; p = 0.001) and days of post-operative drainage (odds ratio = 1.32; p = 0.01) were significant predictors of SSSI. The cases consumed more health care resources at all stages of the medical process.

Our results (1) confirm the strong correlation between the probability of developing DWI and SSSI; (2) indicate that hematoma formation and persistent post-operative drainage increase the risk of SSSI. We hypothesize that post-operative monitoring of patients for hematoma and persistent drainage enables earlier intervention that may lower the risk of developing SSSI and subsequent DWI.