JOA - 2026-06-16 - Journal Article
Triple-Taper Stems in Obese Total Hip Arthroplasty Patients: Complication and Revision Rates from a U.S. Registry.
Sambare TD, Royse KE, Son SJ, Fasig BH, Paxton EW, Eisemon EO, Kelly MP
Topics
Key Takeaway
Triple-taper (Type 3C) femoral stems reduced aseptic revision risk by 53% versus single-taper stems (HR=0.47) and 61% versus dual-taper stems (HR=0.39) in obese THA patients at five years.
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Summary
This study asked whether triple-taper femoral stem design reduces revision risk in obese patients undergoing cementless primary THA. Using multivariable Cox proportional hazard models with surgeon clustering on 25,112 obese patients stratified by Khanuja-Mont classification and obesity class, Type 3C stems demonstrated lower aseptic revision risk versus both Type 1 (HR=0.47) and Type 2 (HR=0.39) stems, with consistent findings across Class I and Class II–IV obesity subgroups. Type 3C stems were also associated with reduced periprosthetic fracture risk.
Key Limitation
The increasing adoption of triple-taper stems from 25.4% to 58.3% over the study period introduces significant temporal confounding, as concurrent improvements in surgical technique, implant manufacturing, and patient selection may independently account for improved outcomes.
Original Abstract
INTRODUCTION
Obesity is a known risk factor for complications and revision following total hip arthroplasty (THA). A triple-taper femoral stem design may improve metaphyseal engagement and rotational stability. This study investigated outcomes in obese patients undergoing cementless primary THA by stem design.
METHODS
We conducted a retrospective cohort study of 25,112 obese patients undergoing unilateral, cementless THA for osteoarthritis between 2018 and 2024. Use of triple-taper increased over the study period (25.4% in 2018 versus 58.3% in 2024). Patients were categorized by stem type per the Khanuja-Mont 2011 classification: Type 1 (single taper), Type 2 (dual taper), and Type 3C (triple-taper) and stratified by obesity class (Class I: body mass index (BMI) 30.0 to 34.9; Classes II to IV: BMI ≥ 35.0). Multivariable Cox proportional hazard models assessed cause-specific revision risk, adjusting for confounders and surgeon clustering.
RESULTS
At five years, cumulative aseptic revision probability was lowest for Type 3C stems. Among Class I obesity patients, Type 3C stems were associated with lower aseptic revision risk compared to Type 1 (hazard ratio (HR) = 0.47, 95% confidence interval (CI) = 0.31 to 0.71, P = 0.0004) and Type 2 stems (HR = 0.39, 95% CI = 0.17 to 0.91, P = 0.029). Similar findings were observed for Class II to IV obesity. Type 3C stems were also associated with lower periprosthetic fracture risk.
CONCLUSIONS
The triple-taper stems are increasingly utilized in obese THA patients and are associated with a reduced aseptic revision and (periprosthetic fracture (PPF) risks compared to Type 1 and 2 stems, supporting the notion that these stems confer a clinically relevant biomechanical advantage.