Radial shaft fracture obliquity as a predictor of distal radioulnar joint instability

We assessed whether radial shaft fracture obliquity measurements on radiographs could predict intra-operative distal radioulnar joint instability. We also clinically validated previously described predictors of distal radioulnar joint instability, which included a fracture line within 7.5 cm of the lunate fossa, radial shortening >5 mm, and ulna styloid fracture. We retrospectively analysed the radiographs of all surgically managed patients in our unit with radial shaft fractures from 2006 through 2016. The degree of obliquity was analysed on the basis of the maximum fracture-line angle in either the coronal or the sagittal plane. A radial shaft fracture obliquity >30 degrees is predictive of distal radioulnar joint instability (P=0.001). Radial fracture shaft obliquity >30 degrees was the most sensitive radiological parameter (76%) for predicting distal radioulnar joint instability. Oblique radial shaft fractures appear to be associated with increased incidence of distal radioulnar joint instability. This radiologic parameter may be used together with established parameters in predicting distal radioulnar joint instability for surgical treatment.