ImportanceMedicare provides near-universal health insurance to US residents aged 65 years or older. How eligibility for Medicare coverage affects racial and ethnic disparities in operative management after orthopedic trauma is poorly understood.ObjectiveTo assess the association of Medicare eligibility with racial and ethnic disparities in open reduction and internal fixation (ORIF) after distal radius fracture (DRF).Design, Setting, and ParticipantsThis retrospective cohort study with a regression discontinuity design obtained data from the Healthcare Cost and Utilization Project all-payer statewide databases for Florida, Maryland, and New York. These databases contain encounter-level data and unique patient identifiers for longitudinal follow-up across emergency departments, outpatient surgical centers, and hospitals. The cohort included patients aged 57 to 72 years who sustained DRFs between January 1, 2016, and November 30, 2019. Data analysis was performed between March 1 and October 15, 2023.ExposureEligibility for Medicare coverage at age 65 years.Main Outcomes and MeasuresType of management for DRF (closed treatment, external fixation, percutaneous pinning, and ORIF). Time to surgery was ascertained in patients undergoing ORIF. Multivariable logistic regression and regression discontinuity design were used to compare racial and ethnic disparities in patients who underwent ORIF before or after age 65 years.ResultsA total of 26 874 patients with DRF were included (mean [SD] age, 64.6 [4.6] years; 22 359 were females [83.2%]). Of these patients, 2805 were Hispanic or Latino (10.4%; hereafter, Hispanic), 1492 were non-Hispanic Black (5.6%; hereafter, Black), and 20 548 were non-Hispanic White (76.5%; hereafter, White) and 2029 (7.6%) were individuals of other races and ethnicities (including Asian or Pacific Islander, Native American, and other races). Overall, 32.6% of patients received ORIF but significantly lower use was observed in Black (20.2% vs 35.4%; P < .001) and Hispanic (25.8% vs 35.4%; P < .001) patients compared with White individuals. After adjusting for potential confounders, multivariable logistic regression analysis confirmed the disparity in ORIF use in Black (odds ratio [OR], 0.60; 95% CI, 0.50-0.72) and Hispanic patients (OR, 0.82; 95% CI, 0.72-0.94) compared with White patients. No significant difference in ORIF use was found among racial and ethnic groups at age 65 years. The expected disparity in ORIF use between White and Black patients at age 65 years without Medicare coverage was 12.6 percentage points; however, the actual disparity was 22.0 percentage points, 9.4 percentage points (95% CI, 0.3-18.4 percentage points) greater than expected, a 75% increase (P = .04). In the absence of Medicare coverage, the expected disparity in ORIF use between White and Hispanic patients was 8.3 percentage points, and this result persisted without significant change in the presence of Medicare coverage.Conclusions and RelevanceResults of this study showed that surgical management for DRF was popular in adults aged 57 to 72 years, but there was lower ORIF use in racial or ethnic minority patients. Medicare eligibility at age 65 years did not attenuate race and ethnicity–based disparities in surgical management of DRFs.