JOA - 2026-08-11 - Journal Article
Collared Stems Are Associated With Reduced Early Aseptic Loosening and All-Cause Revision Rate.
Oettl FC, Dimitriou D, Zingg PO, Hoch A
Topics
Key Takeaway
Collared cementless femoral stems demonstrated a 42% reduced risk of aseptic femoral loosening (HR 0.58) and 35% reduced all-cause revision risk (HR 0.65) at 10 years compared to non-collared stems in 168,493 primary THAs.
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Summary
This national registry study compared 10-year survival of collared vs. non-collared cementless femoral stems in primary THA for OA in patients ≥50 years. Kaplan-Meier survival for aseptic femoral loosening was 99.3% (collared) vs. 98.9% (non-collared), and all-cause revision survival was 96.8% vs. 95.3%. Multivariable Cox regression adjusting for age, BMI, sex, ASA score, and surgical approach confirmed a 42% reduction in loosening risk and 35% reduction in all-cause revision risk with collared stems.
Key Limitation
The 85:15 non-collared to collared ratio introduces significant selection bias, as surgeon preference for collared stems may correlate with unmeasured case-mix variables (bone quality, stem geometry, fixation philosophy) that independently influence loosening risk.
Original Abstract
BACKGROUND
The influence of collar design on femoral stem survival in total hip arthroplasty (THA) remains debated despite its potential biomechanical advantages. This registry analysis investigated whether collared stems demonstrate superior survival compared to non-collared designs in primary THA.
METHODS
A retrospective cohort study using national database data from 2012 to 2024 was conducted. A total of 168,493 primary THAs performed for osteoarthritis in patients aged ≥ 50 years, were analyzed, comprising 143,427 (85.1%) non-collared and 25,066 (14.9%) collared cementless femoral stems. The primary outcome was revision for aseptic femoral loosening (AFL), with all-cause revision as a secondary outcome. Kaplan-Meier survival analysis and multivariable Cox proportional hazards models were used to assess outcomes up to a 10-year follow-up period, adjusting for age, body mass index, sex, American Society of Anesthesiologists score, and surgical approach.
RESULTS
At 10 years, collared stems demonstrated significantly higher survival rates for both AFL (99.3%, 95% confidence interval (CI) 99.1 to 99.6 versus 98.9, 95% CI 98.9 to 99.0, P < 0.001) and all-cause revision (96.8%, 95% CI 96.4 to 97.3 versus 95.3%, 95% CI 95.2 to 95.5, P < 0.001). After adjusting for confounders, collared stems were associated with a 42% reduced risk of revision for aseptic loosening (hazard ratio (HR) 0.58, 95% CI 0.43 to 0.78) and a 35% reduced risk of all-cause revision (HR 0.65, 95% CI 0.59 to 0.73) compared to non-collared stems.
CONCLUSION
This large-scale registry analysis provides compelling evidence that collared femoral stems are associated with significantly lower rates of both aseptic loosening and all-cause revision risk in THA. These findings suggest that collared stems may represent a favorable option for improving outcomes in primary THA for osteoarthritis, though future research incorporating radiological assessment and patient-reported outcomes would further enhance our understanding of this design feature's clinical impact.