Reduced Incidence of Intraoperative Femur Fracture with a Second-Generation Tapered Wedge Stem

Abstract Background Intraoperative fractures during total hip arthroplasty (THA) are more common when using cementless stems. The purpose of this study was to investigate the impact of a new shorter second-generation cementless, tapered wedge stem with improved proximal femoral fit in reducing the incidence of intraoperative fracture. Methods A retrospective study was conducted on primary THA cases performed at a single institution using a first-generation or second-generation cementless stem from 2006-2016. All intraoperative femur fractures were identified, as well as early 30-day postoperative periprosthetic femur fractures, which could represent non-displaced intraoperative fractures that were initially missed. Risk for intraoperative femur fracture was analyzed using logistic regression, accounting for demographic covariates and surgeon. Results Of 6,473 primary THA performed with a cementless, tapered wedge stem during the study period, 3,126 utilized a first-generation stem and 3,347 utilized a second-generation stem. The incidence of intraoperative fracture was 1.79% for first-generation stems and 0.24% for second-generation stems, representing a 7.5-fold reduction of risk for fracture. After accounting for covariates, the odds of intraoperative fracture were 0.33 using the second-generation stem relative to the first-generation stem (p=0.01). However, there was no significant difference in the odds of early 30-day postoperative fractures using the second-generation stem (odds ratio 0.93, p=0.56). Conclusion A new second-generation cementless stem resulted in a 7.5-fold decrease in the incidence of intraoperative femur fracture compared to the preceding stem.