Clinical outcomes of the single-stage revision technique in conversion total hip arthroplasty after failed femoral neck fractures: a two-year follow-up study

BACKGROUND: Conversion to total hip arthroplasty (THA) is associated with higher rates of infection. The purpose of this study is to determine whether applying the surgical technique of single-stage revision can effectively reduce the infection rate of conversion THA after failed femoral neck fractures. METHODS: A retrospective cohort study was conducted on patients who underwent conversion THA after failed femoral neck fracture between January 2019 and December 2022, with a minimum follow-up of 2 years. From January 2019 to March 2020, patients undergoing conversion THA were managed as a primary procedure without synovial fluid culture (Group A). From April 2020 to December 2022, patients undergoing conversion THA were managed with the single-stage revision technique and routine intraoperative synovial fluid culture (Group B). The patients in Group B were matched 1:1 to patients in Group A. Unexpected positive intraoperative culture (UPIC) results were recorded, and PJIs were monitored during the minimum 2-year follow-up period. RESULTS: As intraoperative cultures were only performed in Group B, the unexpected positive intraoperative culture (UPIC) results presented were solely for Group B. Among the patients in Group B who underwent conversion THA, 91% had no UPIC (90 of 99), 7% had a single (either anaerobic bottle or aerobic bottle) UPIC (7 of 99), and 2% had two (both anaerobic and aerobic bottles) UPICs (2 of 99). In Group A, 7 patients (7/99, 7%) experienced PJIs, compared to 1 patient (1/99, 1%) in Group B, showing a significant difference between the two groups (P = 0.030). CONCLUSION: As a novel method for conversion to THA after failed femoral neck fracture, the single-stage revision technique is potentially associated with a lower incidence of PJI. Further evaluation of this technique in larger comparative series is warranted. Video Abstract.