FIVE-YEAR RESULTS AFTER TWO-STAGE EXCHANGE FOR CHRONIC PERIPROSTHETIC HIP INFECTION: DISCREPANCY BETWEEN INFECTION CONTROL AND TRUE TREATMENT SUCCESS

Introduction & Aim Periprosthetic joint infection (PJI) remains one of the most severe complications and is associated with substantial morbidity and mortality. Two-stage exchange arthroplasty is widely regarded as the gold standard treatment for chronic PJI, with reported infection eradication rates of 80–90%. However, in 2019 the Musculoskeletal Infection Society (MSIS) proposed standardized outcome criteria defining treatment success beyond mere infection eradication. Only limited studies have applied these comprehensive criteria, and emerging evidence suggests that true treatment success may be substantially lower than infection control rates alone suggest. The aim of this study was to evaluate 5-year outcomes after two-stage exchange and to compare infection eradication with true treatment success according to MSIS criteria. Methods A retrospective cohort study was performed including all consecutive patients treated for chronic hip PJI with a two-stage exchange procedure between 2018 and 2021 at a tertiary referral center. Clinical and radiographic outcomes were assessed using prospectively collected data combined with entries from an institutional patients registry. Kaplan–Meier survival analyses were performed for the endpoints infection control and treatment success according to MSIS criteria. Differences between survival curves were evaluated using the log-rank test. Results A total of 90 patients were included. Reimplantation was achieved in 69 patients (77%) after a mean interim interval of 101 days (standard deviation 91). Mean follow-up was 52 months (range, 26–78), with two patients (2%) lost to follow-up. After reimplantation, recurrent infection occurred in 7 patients (10%). Additionally, 8 patients (12%) underwent aseptic revision surgery. The 5-year Kaplan–Meier survival rate for the endpoint death was 32% (95% confidence interval [CI] 22–45). Infection control after reimplantation demonstrated a 5-year survival rate of 88% (95% CI 76–94). In contrast, the 5-year survival rate for treatment success according to MSIS criteria was 48% (95% CI 35–60). Comparison of both survival curves revealed a significant difference (log-rank test, p < 0.0001). Conclusions Although infection control after reimplantation reached 88% at five years, overall treatment success according to MSIS criteria was only 48%. This clinically and statistically significant discrepancy demonstrates that infection eradication alone substantially overestimates the true outcome of two-stage exchange arthroplasty. Outcome reporting based solely on infection control may therefore generate overly optimistic expectations for both patients and surgeons. Future studies evaluating treatment strategies for PJI should consistently incorporate standardized MSIS outcome criteria to provide a more comprehensive and clinically meaningful assessment of treatment success.