Are There Differences in Performance Among Femoral Stem Brands Utilized in Cementless Hemiarthroplasty for Treatment of Geriatric Femoral Neck Fractures?
Authors: Shah Ishan , Prentice Heather A. , Okike Kanu , Navarro Ronald A. , Fasig Brian H. , Paxton Elizabeth W. , Grimsrud Christopher D. 
Published: August 2024

Background
For the vast majority of displaced femoral neck fractures in older patients, cemented femoral fixation is indicated because it is associated with a lower risk of periprosthetic fracture than cementless fixation. Nevertheless, cementless fixation continues to be utilized with high frequency for hip fractures in the United States. It is therefore helpful to understand the performance of individual cementless brands and models. Although prior studies have compared femoral stems by design type or stem geometry, there may still be a difference in revision risk according to femoral stem brand given the potential differences within design groupings with regard to manufacturing, implantation systems, and implant design nuances among vendors.

Questions/purposes
(1) Is there a difference in aseptic revision risk among femoral stem brands in patients ≥ 60 years of age who have displaced femoral neck fractures treated with cementless hemiarthroplasty? (2) Is there a difference in revision for periprosthetic fracture among femoral stem brands in patients ≥ 60 years of age with displaced femoral neck fractures treated with cementless hemiarthroplasty?

Methods
A retrospective, comparative, large-database cohort study was conducted using data from Kaiser Permanente’s Hip Fracture Registry. This integrated healthcare system covers more than 12 million members throughout eight regions in the United States; membership has been found to be representative of the general population in the areas served. The Hip Fracture Registry collects details on all patients who undergo hip fracture repair within the organization. These patients are then longitudinally monitored for outcomes after their repair, and all identified outcomes are manually validated through chart review. Patients ages ≥ 60 years who underwent unilateral hemiarthroplasty treatment of a displaced femoral neck fracture from 2009 to 2021 were identified (n = 22,248). Hemiarthroplasties for polytrauma, pathologic or open fractures, or patients who had additional surgeries at other body sites during the same stay, as well as those with prior procedures in the same hip, were excluded (21.4% [4768]). Cemented procedures and those with missing or inconsistent implant information (for example, cement used but cementless implant recorded) were further excluded (47.1% [10,485]). To allow for enough events for evaluation, the study sample was restricted to seven stems for which there were at least 300 hemiarthroplasties performed, including four models from DePuy Synthes (Corail®, Summit®, Summit Basic, and Tri-Lock®) and three from Zimmer Biomet (Medial-Lateral [M/L] Taper®, Trabecular Metal®, and Versys® Low Demand Fracture [LD/FX]). The final sample included 5676 cementless hemiarthroplasties: 653 Corail, 402 M/L Taper, 1699 Summit, 1590 Summit Basic, 384 Tri-Lock, 637 Trabecular Metal, and 311 Versys LD/FX. Procedures were performed by 396 surgeons at 35 hospitals. The mean age and BMI for the cohort was 81 years and 24 kg/m2, respectively; most were women (66% [3733 of 5676]) and White (79% [4488 of 5676]). Based on standardized mean differences, we controlled for age, race/ethnicity, American Society of Anesthesiologist (ASA) classification, anesthesia technique, operative year, average annual surgeon hemiarthroplasty volume, and operative year across the seven stem groups. Of the 5676 patients, 7% (378 of 5676) were lost to follow-up through membership termination at a median time of 1.6 years, and 56% (3194 of 5676) of the patients died during study follow-up. A multivariable cause-specific Cox proportional hazards regression model was used to evaluate the risk for aseptic revision with adjustment for age, gender, ASA classification, depression, operating surgeon, deficiency anemias, time from admission to surgery, and average annual surgeon hemiarthroplasty volume. A random intercept was included to address effects from hemiarthroplasties performed by the same surgeon. Risk for revision for periprosthetic fracture was also evaluated as a secondary outcome.

Results
In the adjusted analysis, the Summit Basic (HR 1.91 [95% confidence interval 1.34 to 2.72]; p < 0.001), the M/L Taper (HR 1.91 [95% CI 1.15 to 3.15]; p = 0.01), and the Versys LD/FX (HR 2.12 [95% CI 1.25 to 3.61]; p = 0.005) had higher aseptic revision risks during follow-up when compared with the Summit. No differences were observed for the Corail (HR 0.57 [95% CI 0.29 to 1.10]; p = 0.09), the Tri-Lock (HR 1.13 [95% CI 0.62 to 2.07]; p = 0.68), or the Trabecular Metal (HR 1.14 [95% CI 0.69 to 1.89]; p = 0.61) compared with the Summit. A higher risk for revision because of periprosthetic fracture was observed with the M/L Taper (HR 2.43 [95% CI 1.29 to 4.58]; p = 0.006) and the Summit Basic (within 3 months of follow-up: HR 1.16 [95% CI 0.60 to 2.25]; p = 0.66; after 3 months of follow-up: HR 2.84 [95% CI 1.36 to 5.94]; p = 0.006) stems when compared with the Summit.

Conclusion
In a cohort of 5676 cementless hemiarthroplasties, we found differences in revision risks among different femoral stem brands. Based on our findings, we recommend against utilization of the Zimmer M/L Taper, DePuy Summit Basic, and Zimmer Versys LD/FX in the treatment of displaced geriatric femoral neck fractures with cementless hemiarthroplasty. Future large registry studies are needed to further elucidate differences in aseptic revision risk among higher performing cementless femoral stems. Although cemented fixation remains the recommended approach based on the best available evidence in hemiarthroplasty treatment of hip fractures, our findings may help to mitigate aseptic revision risk should cementless fixation be chosen.

Level of Evidence
Level III, therapeutic study.