Triple-Taper Collared Stem Morphology Influences Periprosthetic Femur Fracture Risk: A Comparison of Single-, Dual-, Triple-, and Quadrangular-Taper Stems.

Abstract

Stem morphology is an important contributor to periprosthetic femoral fracture (PFF) risk following total hip arthroplasty (THA). Newer-generation triple-taper collared stems may be associated with a lower risk of PFF. Our objective was to compare the incidence of PFFs in triple-taper collared stems to three other cementless stem morphologies. A single-institution retrospective cohort study was performed. All primary THA cases (n = 23,448) from February 2016 to December 2023 using cementless single-taper (n = 8,529), dual-taper (n = 8,514), triple-taper collared (n = 4,024), and quadrangular-taper stems (n = 2,381) from four major implant companies were evaluated. Outcomes were any PFF, intraoperative PFF, and early (90-day) postoperative PFF. Any PFF occurred in 60 of 8,529 (0.70%) single-taper, 114 of 8,514 (1.34%) dual-taper, 15 of 4,024 (0.37%) triple-taper collared, and 26 of 2,381 (1.09%) quadrangular-taper stems (overall difference, P < 0.01). Intraoperative fractures occurred in 30 single-taper (0.35%), 69 dual-taper (0.81%), 10 triple-taper collared (0.25%), and 22 (0.92%) quadrangular-taper stems (P < 0.01). Postoperative fractures occurred in 30 single-taper (0.35%), 47 dual-taper (0.55%), five triple-taper collared (0.12%), and four (0.17%) quadrangular-taper stems (P < 0.01). Collared stems (including quadrangular-taper collared stems) had a lower postoperative fracture rate compared to non-collared stems (0.15 versus 0.44%, P < 0.01). After accounting for age, sex, body mass index, American Society of Anesthesiologists' score, tobacco use, and surgical approach, triple-taper collared stems had a lower risk of intraoperative fracture compared to dual-taper (odds ratio (OR) 0.3, P < 0.01) and quadrangular-taper stems (OR 0.3, P < 0.01). The triple-taper collared stems also had a lower rate of postoperative fracture compared to dual-taper stems (OR 0.3, P < 0.01). In a cohort of over 23,000 patients undergoing cementless THA, triple-taper collared femoral stems had the lowest rates of intra- and postoperative PFF compared to other cementless stem morphologies.