Outcomes of revision total knee arthroplasty after methicillin-resistant Staphylococcus aureus infection.

BACKGROUND: The incidence of infection by methicillin-resistant Staphylococcus aureus (MRSA) in total knee arthroplasty (TKA) is becoming a more frequent concern, as increased morbidity following TKA has been reported for infections by resistant organisms. This study investigates whether MRSA infections are associated with decreased functional scores.

QUESTIONS/PURPOSES: We therefore compared the functional scores, operative times, and rates of reinfection of revision TKA following MRSA infection versus other indications for revision.

METHODS: We retrospectively reviewed charts of 101 patients (103 knees) who underwent mobile bearing TKA revision from January 2003 to September 2006, with a minimum clinical followup of 2 years in 45 knees (44%). We obtained the following indices: WOMAC, Activities of Daily Living Score (ADLS), SF-36, and Knee Society scores (KSS). Three groups of revisions were compared: MRSA infection (n = 6), non-MRSA infection (n = 9), and aseptic failure (n = 30). The three groups were similar in demographics and comorbidities.

RESULTS: The MRSA (166 minutes) and non-MRSA groups (149 minutes) had longer operative times than the aseptic group (121 minutes). With numbers available, there were no differences in ROM, WOMAC, ADLS, KSS, and SF-36, with MRSA separate or combined with all infections. Infection recurrence between MRSA-infected knees and non-MRSA-infected knees was similar.

CONCLUSIONS: While our study was underpowered to detect functional differences between MRSA-infected knees and non-MRSA-infected knees it does add data to the literature. Knees revised for infection have longer operative times and more frequent infection after revision. The reason for increased operative times is unclear.

LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.