Decreased Revision Risk with Cementless Collared Metadiaphyseal-Filling Stems Compared to Cemented Fixation in Patients 65 Years and Older.
Background: Compared to other cementless designs, collared metadiaphyseal-filling femoral stems are associated with a lower risk of revision and periprosthetic femoral fracture after total hip arthroplasty (THA) in patients ≥ 65 years. However, it is unclear how these designs compare to cemented femoral stems. We utilized the American Joint Replacement Registry (AJRR) to examine the risk of revision comparing cementless collared metadiaphyseal-filling versus cemented femoral stem designs.
Methods: Data from 2012 to 2021 was analyzed in patients ≥ 65 years, linked to Centers for Medicare and Medicaid data. We identified 79,022 primary THAs, stratified into two groups: cementless collared metadiaphyseal-filling stems (n = 61,854) and cemented fixation (n = 17,168). Inverse-probability-of-treatment-weighting (IPTW) cause-specific Cox proportional hazard models were used to evaluate the risks of all-cause revision and revision for periprosthetic femoral fracture, aseptic loosening, dislocation, and infection.
Results: Compared to cemented stems, cementless collared metadiaphyseal-filling stems showed a lower risk of all-cause revision (hazard ratio [HR] 0.46, 95% confidence interval [CI] 0.38 to 0.56, P < 0.001), aseptic loosening (HR 0.35, CI 0.22 to 0.57, P < 0.001), dislocation (HR 0.39, CI 0.26 to 0.58, P < 0.001), and infection (HR 0.53, CI 0.36 to 0.78, P = 0.001). There was no difference in periprosthetic femoral fracture risk (HR 0.80, CI 0.45 to 1.42, P = 0.44).
Conclusions: In this cohort of patients undergoing primary THA, cementless collared metadiaphyseal-filling stems were associated with decreased risk of all-cause revision, revision for aseptic loosening, dislocation, and infection, but there was no difference in periprosthetic femoral fracture risk compared to cemented stems. Further study of cementless collared metadiaphyseal-filling designs compared to cemented fixation is warranted as there may be benefits of decreased revision risk with cementless fixation.