Triple-Taper Stems in Obese Total Hip Arthroplasty Patients: Complication and Revision Rates From a United States...

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.

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 30.0 to 34.9; classes II to IV: body mass index ≥ 35.0). Multivariable Cox proportional hazard models assessed cause-specific revision risk, adjusting for confounders and surgeon clustering.

At 5 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 than type 1 (hazard ratio = 0.47, 95% confidence interval = 0.31 to 0.71, P = 0.0004) and type 2 stems (hazard ratio = 0.39, 95% confidence interval = 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.

The triple-taper stems are increasingly utilized in obese THA patients and are associated with a reduced aseptic revision and (periprosthetic fracture) risks compared to type 1 and 2 stems, supporting the notion that these stems confer a clinically relevant biomechanical advantage.