Uncemented femoral stem design might have an impact on postoperative periprosthetic femur fracture pattern. A Comparison between flat-wedge and dual-wedge stems

Abstract

IntroductionType I, flat-wedge and type II, dual-wedge stems are currently two common stem types used in primary, uncemented hip arthroplasty. The prevalence of periprosthetic femur fracture is higher in type I stems, possibly because of the different shapes and areas of bone contact. We aimed to compare the fracture pattern, stem stability during the fracture and type of subsequent procedures in periprosthetic femur fractures between type I and II stems. Materials and MethodsThis was a retrospective, cross-sectional study conducted in a single tertiary referral hospital of Taipei, Taiwan. We included primary hip arthroplasty procedures using type I or type II stems complicated with postoperative periprosthetic femur fractures. We recorded the age, sex, ASA grade, index procedure, institution of where the index procedure was performed, trauma mechanism, time from index procedure to fracture, procedure for periprosthetic fracture and radiographic parameters including Dorr type, Vancouver classification, stem stability, fracture pattern, type and brand of the stems for analysis. ResultsWe included 132 patients who had undergone surgery for periprosthetic femur fracture for type I (N = 46) or type II (N = 86) stems. The mean age was 74.5 years and 52.3% of the patients were female. Type I stems were associated with a higher proportion of a complex fracture pattern (52.2% vs. 8.2%), femoral stem loosening (78.2% vs. 60.4%) and a higher rate of revision stem procedures (69.6% vs. 50.0%) compared with type II stems. Using multivariate analysis, type I stem was the only factor for a complex fracture pattern in the overall population (aOR: 23.60, 95% CI: 6.54–85.16), hemiarthroplasty (aOR: 160.50, 95% CI: 9.77–2635.95) and total hip arthroplasty (aOR: 14.17, 95% CI: 2.92–68.79) subgroups. ConclusionWe observed a difference in fracture patterns between type I and type II stems. Type I stems appear to be an independent risk factor for a complex fracture pattern in patients who had undergone primary hip arthroplasty.