Radiological outcomes of distal radius extra-articular fragility fractures treated with extra-focal kirschner wires

The classical colles fracture (extra-articular, dorsally angulated distal radius fracture) in patients with osteoporotic bone is becoming increasingly more frequent. There still appears to be no clear consensus on the most appropriate surgical management of these injuries. The purpose of this study is to appraise the use of percutaneous extra-focal pinning, in the management of the classical colles fracture.

We retrospectively analysed 72 consecutive cases of colles fractures treated with inter-fragmentary k-wire fixation, in female patients over 60 years of age, in two orthopaedic centres, under the care of 12 different orthopaedic surgeons. We correlated the radiographical distal radius measurements (ulnar variance, volar tilt, and radial inclination) at the pre-operative and intra-operative stages with the final radiographical outcome.

Mean dorsal angulation was 21 degrees at time of presentation. Closed reduction significantly improved fracture position to a mean of 2.7 degrees volar angulation (p<0.05). Mean angulation at time of k-wire removal was 1.6 degrees dorsal, this was not significant in comparison to post-reduction measurements (p<0.05). Mean ulnar variance at time of presentation was 2.5mm (range 7.4 to -4.2). Reduction improved fracture displacement to a mean of 0mm, which was statistically significant (p<0.05). Mean ulnar variance at time of k-wire removal was 2.4mm (p<0.05). 56.8% of cases demonstrated radial shortening of 2mm or more.

In female patients over 60 years of age, the best predictor of radial length, when k-wire fixation is to be used, is the radial length prior to fracture reduction. Thus if there is radial shortening visible in the initial radiographs as measured in terms of ulnar variance, one should consider a method of fixation other than inter-fragmentary k-wires.