Cast-treated distal radius fractures: a prospective cohort study of radiological outcomes and their association with impaired calcaneal bone mineral density

We hypothesized that treating distal radius fractures with cast only or closed reduction and cast is associated with high malunion risk and that the risk is higher in patients with low bone mineral density (BMD).

We prospectively studied 130 patients aged 40 years or older with distal radius fractures treated with cast only (87 patients) or closed reduction and cast (43 patients). Radiographs were obtained before treatment, after reduction (in the closed reduction group), and at 1 year. We measured calcaneal BMD with DXA scanner and calculated T scores. We calculated radiological changes from baseline (initial radiographs in cast only and post-reduction radiographs in closed reduction patients) to 1 year. We assessed the relationship between BMD status (normal, osteopenia or osteoporosis) and baseline-to-1-year worsening in volar tilt, ulnar variance, and radial inclination with analysis of covariance adjusting for baseline radiological values. We used receiver operating characteristic (ROC) analysis to determine the ability of T scores to distinguish patients with severe malunion (dorsal tilt >25° and/or ulnar variance ≥5 mm) from those with less severe or no malunion.

In both treatment groups, baseline radiological variables had deteriorated at 1 year, more in the closed reduction group. Compared to patients with normal BMD, those with osteoporosis had significantly greater worsening in volar tilt and radial inclination but did not differ in ulnar variance worsening. Severe malunion was found in 34 fractures (26 %, 15 in cast only group); T scores had a modest ability in distinguishing severe malunion (area under ROC curve 0.67, 95 % CI 0.56–0.78, p = 0.003).

Closed reduction and cast is not an effective treatment for distal radius fractures if radiological graphic outcomes are considered. There is a higher risk of malunion involving dorsal and radial tilt in patients with osteoporosis. Calcaneal BMD measurement may have some benefit in predicting the risk of severe malunion.