Two-stage exchange arthroplasty for infected total knee arthroplasty: predictors of failure.

Background: In North America, a two-stage exchange arthroplasty remains the preferred surgical treatment for chronic periprosthetic joint infection (PJI). Currently, there are no proper indicators that can guide orthopaedic surgeons in patient selection for two-stage exchange or the appropriate conditions in which to reimplant.

Questions/purposes: To identify (1) the rate of recurrent PJI after two-stage exchange and (2) the role of 15 presurgical and 11 operative factors in influencing the outcome of two-stage revision.

Patients And Methods: From a prospective database we identified 117 patients who had undergone two-stage exchange arthroplasty for PJI of the knee from 1997 to 2007. Failure of two-stage revision was defined as any treated knee requiring further treatment for PJI. We identified 15 presurgical and 11 surgical factors that might be related to failure. Minimum followup was 2 years (average, 3.4 years; range, 2-9.4 years).

Results: Thirty-three of 117 reimplantations (28%) required reoperation for infection. Age, gender, body mass index, and comorbidity indices were similar in both groups. Multivariate analysis provided culture-negative (odds ratio [OR], 4.5; 95% confidence interval [CI], 1.3-15.7), methicillin-resistant organisms (OR, 2.8; 95% CI, 0.8-10.3), and increased reimplantation operative time (OR, 1.01; 95% CI, 1.0-1.03) as predictors of failure. ESR and CRP values at the time of reimplantation and time from resection to reimplantation were not predictors.

Conclusions: Our observations suggest the failure rate after two-stage reimplantation for infected TKA is relatively high. Culture-negative or methicillin-resistant PJI increases the risk of failure over four- and twofold, respectively. We identified no variables that would guide the surgeon in identifying acceptable circumstances in which to perform the second stage.

Level Of Evidence: Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.