MR imaging of suspected acute spinal instability

Twenty-two patients with suspected acute vertebral instability were imaged within 48 h of injury using a 0.5 Tesla magnet. In all patients plain radiographs, T1 weighted gradient echo (GE) and STIR sequences were performed. Two radiologists blindly evaluated the magnetic resonance imaging (MRI) scans defining injuries with bony or soft tissue disruption of both columns as unstable. Indirect signs of instability such as soft tissue haemorrhage were recorded and correlated where possible with operative findings. Sixteen patients were radiologically unstable on MRI, five more than on plain films alone. Instability was confirmed operatively in 10 patients. The six other patients with unstable injuries were treated conservatively. Two of these patients had evidence of increased deformity before fracture union. The radiologically stable patients were treated as such and at 6-month review showed no evidence of progressive instability. The presence of soft tissue haemorrhage in the interspinous gap was not associated with ligament rupture unless actual discontinuity was demonstrated at that level. We conclude that using MRI acutely, most unstable spinal injuries can be rapidly and accurately evaluated without the need for further imaging.