Articular Void Sign on MRI in Intra-Articular Distal Radius Fracture Patients

Author(s): Ryoichi Shibuya

Introduction: MR imaging provides more information about tissue status than plain radiographs. The purposes of this study were to investigate the relationship between plain radiograph, MR imaging and wrist function in patients with intra-articular distal radius fracture treated using volar locking plate.

Materials and methods: The plain radiographs, CT scans, and MRI findings of 27 patients were examined. The mean follow-up was 2 years (1 year - 3 years and 6 months). The range of motion of the wrist joint was evaluated as % arc, which is the ratio of the range of motion to that on the healthy side, expressed as a percentage.

Results: In 27 patients, there were 6 type C1, 3 C2, and 18 C3 fractures. The mean step measured on plain radiographs was 0.4 ± 0.7 mm (range, 0 to 2 mm), and that on T1-weighted MR image was 0.6 ± 0.9 mm (range 0 to 3 mm). The mean % arc was 88.1 ± 11.3% (range, 48.5 to 100 %). Plain radiographs showed an area of sclerotic change in the subchondral bone in three patients. In two of the three patients, the area corresponding to this sclerotic area was a homogenic low intensity area on the T1-wegited MR images. This area consists of components with unspecified shape and intensity on T2-wegited MR images and designated as “articular void”.

Conclusions: This articular void was considered to include necrotic bone, fibrous tissue and suggested to be one of a cause of impairment of joint function.