Inadequate Metadiaphyseal Fill of a Modern Taper Wedge Stem Increases Subsidence and Risk of Aseptic Loosening: Technique and Distal Canal Fill Matter!

Abstract Introduction Adequate interference fit and mechanical stability through optimal surgical technique are essential to prevent subsidence and loosening in cementless total hip arthroplasty (THA). The purpose of this study was to determine the effect of surgical technique on radiographic subsidence and subsequent stability of a modern taper-wedge cementless stem. Methods A retrospective review of 250 consecutive cementless primary THAs performed by two surgeons was completed. Surgeon A vigorously broached, maximizing the mediolateral stem dimension and confirmed final broach stability with a torsional test; whereas Surgeon B did not. All patients received identical taper-wedge stems. Preoperative bone morphology (canal-flare index, CFI), postoperative subsidence and canal fill were radiographically assessed. Results CFI was not different between groups (p=0.747). There was significantly less subsidence at one-month for Surgeon A (0.3 vs. 1.3mm, p Conclusion These observations support that maximizing mediolateral canal fill and avoiding under-sizing the femoral implant with meticulous broaching technique minimizes subsidence and optimizes stability of modern cementless taper-wedge stems. Failure to optimize canal fill with appropriate broaching and surgical technique may predispose femoral components to failure from aseptic loosening.