Predictors of early and late instability following conservative treatment of extra-articular distal radius fractures

The purpose of this study was to identify radiological predictors of early and late instability following conservative treatment of extra-articular distal radius fractures.

An observational study design was employed using patient records and standardized radiological follow-up examinations as data sources. The database at a single institution was used to identify all patients with extra-articular distal radius fractures over the course of 1 year. A total of 71 patients with extra-articular distal radius fractures (50 dorsally displaced, 21 undisplaced) fulfilled the inclusion criteria. Patients were predominantly female (87%) with a pooled mean age of 64.9 years. All patients with displaced extra-articular distal radius fractures underwent closed reduction with subsequent cast immobilization. Undisplaced fractures were simply treated with cast immobilization. The primary outcomes were early (1 week) and late (6 weeks) instability of the fracture. Instability was defined as: (1) dorsal tilt >15°, (2) volar tilt >20°, (3) ulnar variance >4 mm, (4) radial inclination <10°.

Degree of radial shortening and volar tilt were predictive of early instability (p<0.05), with dorsal comminution also approaching statistical significance (p=0.06). Radial inclination, age, radial shortening, and volar tilt were predictive of late failure (p<0.05). An unexpected result showed that one-third of undisplaced fractures went on to fail, most of which occurred in those patients over the age of 65 years.

An awareness of independent predictors of instability in extra-articular distal radius fractures is helpful in anticipating the final alignment outcome.