What happens to the posterior comminution in extra-articular fractures of the distal radius treated with volar locking plates?

Extra-articular fractures of the distal radius with posterior displacement are typically treated with volar locking plates. However, this fixation method does not address the posterior comminution, which seems to have no impact on the final result. The purpose of this study was to determine the fate of the posterior comminution. This was a retrospective study of 22 patients over 50 years old with a distal radius fracture. A preoperative computed tomography (CT) scan was performed to evaluate the comminution. All fractures were fixed with a volar locking plate. All patients underwent a bone density scan. Patients were reviewed at 6 months post-operative to determine their clinical, radiological and functional outcomes. The CT scan was performed again to determine the fate of the comminution. At 6 months post-operative, 82% of patients had an oval metaphyseal defect. The mean volume of this defect was 1.86 mL. The contents of this defect most closely resembled fat. There was no statistical link between the defect's volume and the various parameters studied. On the other hand, the defect's density was positively related to the functional outcome and negatively related to the patients’ body mass index. Because of the compression experienced by the cancellous bone, a distal metaphyseal defect often persists after consolidation in dorsally displaced distal radius fractures. The posterior comminution is ultimately of little consequence.