The influence of femoral component design on postoperative periprosthetic femoral fracture after uncemented direct anterior total hip arthroplasty in the elderly

Introduction: Aging populations and expanding indications will greatly increase the volume of total hip arthroplasty (THA) in all age groups, including patients over 70 years old. Minimally invasive, uncemented direct anterior THA offers potential advantages for treating elderly patients. However, literature indicates higher risks of postoperative periprosthetic femur fractures (PPFFs) with both direct anterior THA and uncemented femoral stems. This retrospective study investigates the influence of femoral stem design on PPFF incidence in uncemented direct anterior THA among patients older than 70 years. Methods: 557 primary THAs in patients aged 70 or over were reviewed for PPFFs from a consecutive series of 2011 patients undergoing direct anterior THA from a fellowship-trained adult reconstruction surgeon from 2015 to 2020. Exclusion criteria included age (<70) and posterior approach. For the first cohort of 361 patients (79 of which passed exclusion criteria) the surgeon used a single-tapered, proximally porous coated, collarless titanium stem. For the next 1650, (478 of which passed exclusion), the surgeon used a dual-tapered, collared, hydroxyapatite-coated titanium stem. Included patients were carefully monitored until March 2021 for PPFFs. A Fisher's exact test was used to compare the incidence PPFFs between the 2 implant designs. Results: 2 of 79 (2.5%) patients had atraumatic PPFFs at an average of 19.5 days post-operatively in the first cohort. Both experienced a Vancouver type B2 periprosthetic fracture and required femoral revision. No patients (0/478, 0%) in the second group sustained a PPFF. (P = 0.0199). Conclusion: In this comparison, the dual-taper, hydroxyapatite-coated implant had a significantly lower PPFF rate among elderly patients than a single-taper, proximally porous stem without a collar.