Assessing the Relationship Between Bone Density and Loss of Reduction in Nonsurgical Distal Radius Fracture Treatment

Purpose: Whether low bone mineral density affects loss of reduction for distal radius fractures (DRFs) managed without surgery is unknown. Our purpose was to understand how bone mineral density, based on second metacarpal cortical percentage (2MCP) measurement, affects DRF healing after nonsurgical treatment. Methods: We retrospectively reviewed 304 patients from 2 health systems with DRFs treated without surgery. The AO classification, 2MCP (<50% indicating osteoporosis), and fracture stability based on Lafontaine criteria were determined from prereduction radiographs. Radial inclination, radial height, volar tilt, ulnar variance, and intra-articular stepoff were measured on initial and 6-week final follow-up radiographs and compared. Bivariate analysis was used to evaluate the association between Lafontaine criteria or 2MCP and changes in radiographic parameters. Radiographic parameters with significant associations in bivariate analysis were evaluated in multivariable models adjusted for age, sex, initial radiographic parameters, reduction status, and AO fracture type. Results: Across all patients, after 6 weeks of nonsurgical treatment, ulnar variance (shortening of the radius) increased by an average of 1.4 mm. Bivariate analysis showed that lower 2MCP and unstable fractures per Lafontaine criteria were each significantly associated with an increase in ulnar variance (P < .05). In adjusted multivariable models, having both 2MCP less than 50% and an unstable fracture together was associated with an additional 1.2-mm increase in ulnar variance (P < .05). Conclusions: A 2MCP in the osteoporosis range and unstable fractures by Lafontaine criteria were each associated with a significant increase in ulnar variance after nonsurgical treatment for DRFs. Patients with unstable fractures and 2MCP less than 50% are likely to have an additional increase of greater than 1 mm in ulnar variance at the end of nonsurgical fracture treatment than patients with similar injuries, but without these features. Using initial radiographs to identify patients with low bone mineral density that may be at risk for more substantial loss of reduction can assist with decision making for managing DRFs. Type of study/level of evidence: Prognostic IV.