Hip bone density is associated with concomitant distal ulna fracture in the setting of distal radius fracture

Lower hip bone density showed the most consistent association with distal ulna involvement in surgically treated distal radius fractures, whereas local fracture severity showed minimal discriminatory value. Hip bone density was particularly associated with the ulnar metaphyseal subtype, characterizing conditional fracture-pattern variation within this selected population.

To characterize clinical and skeletal features across fracture subtypes within surgically treated low-energy distal radius fractures and to distinguish ulnar metaphyseal fracture from ulnar styloid fracture when ulna involvement occurs.

This retrospective cross-sectional study included adults aged ≥ 45 years with surgically treated low-energy distal radius fracture (2020-2024). Patients were categorized into three groups: isolated distal radius fracture without distal ulna fracture (DRF group); distal radius fracture with isolated ulnar styloid fracture (USF group); and distal radius fracture with ulnar metaphyseal fracture, with or without ulnar styloid fracture (UMF group). Candidate variables included sex, age, hip and spine bone mineral density expressed as a percentage of the young adult mean reference value (YAM), body mass index, and distal radius fracture severity according to the AO/OTA classification. Univariable and multivariable logistic regression analyses were conducted in two stages: (1) USF + UMF versus DRF and (2) UMF versus USF.

Among 236 patients, DRF, USF, and UMF accounted for 85, 129, and 22 cases, respectively (64.0% with distal ulna involvement). Low hip-YAM (≤ 70%) showed the most consistent association with ulna involvement across both analytic stages, with a stronger association in the second stage differentiating UMF from USF. Other variables, including radius fracture severity, exhibited minimal or no association.

In patients with surgically treated distal radius fracture, lower hip bone density was consistently associated with distal ulna involvement, particularly the metaphyseal subtype, characterizing conditional fracture-pattern variation within this selected surgical population.