Collared Stems Are Associated With Reduced Early Aseptic Loosening and All-Cause Revision Rate.

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.