Characterization of the Dorsal Ulnar Corner in Distal Radius Fractures in Postmenopausal Females: Implications for Surgical Decision Making

Purpose: To characterize the dorsal ulnar corner fragment with regard to size and morphology using 3-dimensional software and computed tomography (CT) scans, as it presents in low-energy intra-articular distal radius fractures occurring in the female postmenopausal population. Methods: A multicenter retrospective review was conducted to identify postmenopausal females with low-energy distal radius fractures treated surgically at level-1 trauma centers. Patients with low-energy injuries with preoperative CT scans were included. The Digital Imaging and Communications in Medicine (DICOM) data from CT scans were used to reconstruct intra-articular fracture patterns. The dorsal ulnar fragment was isolated in each CT scan and measured, then normalized based on lunate depth. Results: Eighty patients met the inclusion criteria. The mean dimension measurements of the dorsal ulnar corner were dorsal surface height, 9.82 ± 5.02 mm (95% confidence interval [95% CI], 8.72–10.92); dorsal surface width, 9.06 ± 3.72 mm (95% CI, 8.25–9.88); articular surface width, 7.44 ± 3.92 mm (95% CI, 6.58–8.30); articular surface depth, 4.14 ± 2.39 mm (95% CI, 3.62–4.67). The mean lunate depth measurement (17.52 ± 1.48 mm) was used to normalize articular surface depth demonstrating that, on average, the dorsal ulnar corner comprises 23.6% of the articular surface ± 13.6% (95% CI, 20.7–26.6). Conclusions: The mean articular surface depth of the dorsal ulnar corner fragment in this study was less than 5 mm, accounting for approximately 24% of the volar-dorsal width of the distal radius at the lunate facet. Clinical relevance: These data expand current understanding of the morphology and size of the dorsal ulnar corner fracture fragment. If fixation of this fragment is a goal, surgeons may need to use longer screws that penetrate closer to the dorsal cortex than those required for extra-articular fractures or to consider alternative methods of fragment-specific fixation for adequate capture of this fragment.