RISK FACTORS FOR REINFECTION AFTER TWO-STAGE HIP PROSTHESIS EXCHANGE: A PROSPECTIVE COHORT STUDY

Aim The objectives of our study were (1) to determine the success rate of 2-stage total hip arthroplasty (THA) implant exchange for the treatment of periprosthetic joint infection (PJI) and (2) to evaluate relevant risk factors for reinfection and subsequent revision surgeries after reimplantation. Method After institutional board approval we conducted a prospective analysis of 187 patients who underwent a 2-stage revision THA after being diagnosed with PJI from 2013 to 2019. The mean duration of follow-up was 54.2 ± 24.9 months (>36 months) and the mean duration of 1st to 2nd stage interval was 9.8 ± 8.9 weeks (>2 weeks). All patients remained in a Girdlestone situation without a spacer between the two stages of the treatment. Infection recurrence and reoperation rates were estimated through Kaplan-Meier survival analysis and the investigation for potential risk factors was performed using Cox hazard regression. Results The overall success rate in our cohort was 85.6% with an estimated cumulative survival of 84% (95% CI = 79.8-89.9%). The estimated risk for reinfection was 9% for the first 6 months, 11.5% for the first year and 14% for the first two years postoperatively. Seven out of 27 reinfections were persistent infections (26%), whereas the remaining 20 (74%) were new infections caused by a different pathogen. DDT (difficult-to-treat) or high virulence pathogens were found to be significant independent risk factors for infection recurrence. (HR=1.31, 95% CI: 1.47-9.36, p=0.006 and HR=1.35, 95% CI: 1.73-8.57, p=0.001). Any history of another previous 2-stage implant exchange of the affected hip was also found to be an independent predictor for re-infection after reimplantation (HR=1.28, 95% CI: 1.33-9.62, p=0.01). Overall reoperation and revision rates were 26.2% and 16.6% respectively during the entire course of the follow up. Re-infected patients had 80% higher probability for reoperation than the non-infected ones (p<0.001, Log-rank= 102.6) and they were 55% more likely to undergo revision surgery during their follow up (p<0.001, Log-rank=55.4). Conclusions Reinfection rates after 2-stage THA revision for PJI still remain high, especially in affected patients with prior failed 2-stage implant exchange or challenging infections involving high-grade or difficult-to-treat pathogens. PJI recurrence seems to favor new infections caused by different pathogens rather than infections persistence.