Risk Factors for Subsidence of Modular Fluted Tapered Stems Used During Revision Total Hip Arthroplasty for Periprosthetic Hip Fractures

Background: The objective of this study was to review Vancouver B ₂ and B ₃ periprosthetic hip fractures treated with uncemented modular fluted tapered stems to analyze survivorship, risk factors for stem subsidence, and clinical outcomes. Methods: We identified 61 Vancouver B ₂ and B ₃ periprosthetic hip fractures treated with modular fluted tapered implants. Survivorship, radiographic outcomes, and clinical outcomes were assessed. The mean age at the time of surgery was 72 years, mean body mass index was 30, and mean follow-up was 4.5 years (range, 2-10 years). Results: Survivorship free of reoperation or implant revision at 5 years was 89% and 93%, respectively. Eight (13%) stems subsided a mean distance of 18 ± 8 mm (range, 8-28 mm). Stem subsidence was not correlated with age, gender, Vancouver fracture classification, stem bypass, stem length, or stem diameter. Subsidence was correlated with Dorr C type femora (50% vs 7%, 95% confidence interval 9%-72%; P =.007) and strut grafting (50% vs 9%, 95% confidence interval 6%-70%; P =.01). All cases of subsidence stabilized without revision. Subsidence was not correlated with nonunion, reoperation, revision, or a clinical outcome. Conclusions: Modular fluted tapered stems had excellent survivorship free of reoperation and implant revision when used for the treatment of Vancouver B ₂ and B ₃ periprosthetic femur fractures. Poor bone morphology and the use of strut grafts, both proxies for compromised bone stock and distal fracture patterns, were correlated with stem subsidence. All subsided stems stabilized, and noted subsidence did not portend a worse clinical outcome. Level of Evidence: Level III, retrospective cohort.