Risk Factors for Early Conversion Total Hip Arthroplasty after Pipkin IV Femoral Head Fracture.

Objectives:To determine risk factors for early conversion total hip arthroplasty (THA) in Pipkin IV femoral head fractures.Design:Retrospective cohort.Setting:Two level I trauma centers.Patients and Intervention:One hundred thirty-seven patients with Pipkin IV fractures meeting inclusion criteria with 1 year minimum follow-up managed from 2009 to 2019.Main Outcome Measurement:Patients were separated into groups by the Orthopaedic Trauma Association/AO Foundation (OTA/AO) classification of femoral head fracture: 31C1 (split-type fractures) and 31C2 (depression-type fractures). Multivariable regression was performed after univariate analysis comparing patients requiring conversion THA with those who did not.Results:We identified 65 split-type fractures, 19 (29%) underwent conversion THA within 1 year. Surgical site infection (P = 0.002), postoperative hip dislocation (P < 0.0001), and older age (P = 0.049) resulted in increased rates of conversion THA. However, multivariable analysis did not identify independent risk factors for conversion. There were 72 depression-type fractures, 20 (27.8%) underwent conversion THA within 1 year. Independent risk factors were increased age (P = 0.01) and posterior femoral head fracture location (P < 0.01), while infrafoveal femoral head fracture location (P = 0.03) was protective against conversion THA.Conclusion:Pipkin IV fractures managed operatively have high overall risk of conversion THA within 1 year (28.5%). Risk factors for conversion THA vary according to fracture subtype. Hip joint survival of fractures subclassified OTA/AO 31C1 likely depends on patient age and postoperative outcomes such as surgical site infection and redislocation. Pipkin IV fractures subclassified to OTA/AO 31C2 type with suprafoveal and posterior head impaction and older age should be counseled of high conversion risk with consideration for alternative management options.