Does body mass index independently affect functional outcomes after conservatively treated distal radius fractures? a retrospective cohort study

Obesity has been associated with inferior outcomes in several musculoskeletal conditions; however, its independent effect on functional recovery after conservatively treated distal radius fractures remains uncertain. This study aimed to evaluate whether body mass index (BMI) independently influences long-term functional outcomes following nonoperative management of distal radius fractures. This retrospective cohort study was conducted at a single tertiary trauma center between January 2023 and December 2025. During the study period, 188 adult patients were treated for distal radius fractures, of whom 141 were managed conservatively. Among these, 129 patients with complete 12-month Disabilities of the Arm, Shoulder and Hand (DASH) scores were included in the final analysis. Fractures were classified according to the AO system. BMI was analyzed as both a continuous variable and according to World Health Organization categories. Nonparametric tests and Spearman correlation were used for univariate analyses. Multivariable linear regression was performed to evaluate the independent association between BMI and 12-month DASH scores after adjustment for age, sex, and fracture type. The mean age was 50.3 ± 15.3 years, and the mean BMI was 27.6 ± 4.5 kg/m². The median 12-month DASH score was 11.25 (interquartile range [IQR], 6.75–22.50). BMI demonstrated a weak positive correlation with 12-month DASH scores (ρ = 0.255, p = 0.0036), and obese patients exhibited higher DASH scores compared with normal-weight patients (p = 0.007). However, in multivariable analysis, BMI was not independently associated with 12-month DASH scores (β = 0.283, p = 0.201). Increasing age (β = 0.307, p < 0.001) and AO type B/C fractures (β = 6.777, p = 0.008) were independently associated with worse functional outcomes. Higher BMI was associated with worse unadjusted functional outcomes but did not independently predict 12-month DASH scores after adjustment for age and fracture severity. These findings suggest that BMI alone may not be a reliable prognostic indicator in conservatively treated distal radius fractures.