JOA - 2026-04-16 - Journal Article
High-Offset Stems Are Associated With an Increase in Revision Due to Femoral Loosening and All-Cause: A Registry-Based Observational Retrospective Cohort Study.
Oettl FC, Andronic O, Dimitriou D, Zingg PO, Hoch A
Topics
Key Takeaway
Total femoral offset >48 mm is associated with an 83% increased risk of revision for aseptic femoral loosening (HR 1.83) and 20% increased all-cause revision risk in cementless THA, with collared stems reducing revision risk by 50%.
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Summary
This national registry study evaluated whether total femoral offset (stem + head combined) predicts revision for aseptic femoral loosening (AFL) and all-cause revision (ACR) in cementless THA for OA using the five most common stem designs. Each 1-mm increase in TFO conferred a 4.1% increase in AFL revision risk (HR 1.04, 95% CI 1.02–1.06), and TFO >48 mm yielded HR 1.83 for AFL and HR 1.20 for ACR versus the standard offset group. Collared stems were independently associated with a 50% reduction in revision risk.
Key Limitation
Registry data preclude determination of whether high TFO was an independent biomechanical risk factor or a surrogate for underlying anatomy (coxa vara, dysplasia) that independently increases loosening risk, limiting causal inference.
Original Abstract
BACKGROUND
The influence of femoral offset on the survival of cementless femoral stems in total hip arthroplasty (THA) remains unclear. This study aimed to evaluate the influence of total femoral offset (TFO - stem plus head) on the risk of revision for early aseptic femoral loosening (AFL) and all-cause revision (ACR).
METHODS
A retrospective cohort study was conducted using data from a national registry for all primary, cementless THAs performed for osteoarthritis between 2012 and 2024 with the five most common stem designs. The final cohort consisted of 93,027 hips, and a total of 419 revisions for AFL and 2,592 for ACR were observed. The primary exposure was TFO, analyzed as both a continuous variable and as three categories (less than 42 mm, 42 to 48 mm, and greater than 48 mm). The primary endpoint was revision surgery for AFL, and the secondary endpoint was ACR. Kaplan-Meier survival analyses and multivariable Cox proportional hazards models were used to estimate survival and hazard ratios (HRs) while adjusting for confounders.
RESULTS
The 10-year implant survival for AFL was significantly lower in the high-offset group (98.9%, 95% confidence interval (CI) 98.6 to 99.1) compared to the standard (99.3%, 95% CI 99.2 to 99.4) and low-offset groups (99.5%, 95% CI 99.4 to 99.6; P < 0.001). After adjusting for confounders, the risk of revision for AFL increased by 4.1% for every 1-mm increase in TFO (HR 1.04, 95% CI 1.02 to 1.06). The high-offset group (greater than 48 mm) had a significantly increased risk of revision for AFL (HR 1.83, 95% CI 1.28 to 2.63) and ACR (HR 1.20, 95% CI 1.04 to 1.38).
CONCLUSION
In this registry population, higher TFO combinations are associated with an 83 and 20% increased risk of revision for aseptic femoral loosening and a risk of all-cause revision following cementless THA. Collars were associated with a 50% reduction in revision risk.