Flexion-extension cervical spine plain films compared with MRI in the diagnosis of ligamentous injury

The purpose of this study was to compare flexion-extension (FE) plain films with MRI as the gold standard in the diagnosis of ligamentous injury (LI) of the cervical spine after trauma. A retrospective review of patients sustaining blunt trauma from January 2000 to December 2008 (n = 22929) who had both FE and MRI of the cervical spine was performed. Two hundred seventy-one patients had 303 FE films. Forty-nine also had MRI. The average Injury Severity Score was 15.6 +/- 10.2, Glasgow Coma Scale was 13.8 +/- 3.5, lactate 2.2 +/- 1.7 mmol/L, and hospital stay of 8 +/- 11.2 days. FE failed to identify all eight LIs seen on MRI. FE film sensitivity was 0 per cent (zero of eight), specificity 98 per cent (40 of 41), positive predictive value 0 per cent (zero of one), and negative predictive value 83 per cent (40 of 48). Although classified as negative for purposes of analysis, FE was incomplete 20.5 per cent (62 of 303) and ambiguous 9.2 per cent (28 of 303) of the time. The charge of FE is $535 so $48150 (90 incomplete/ambiguous films) could have been saved by eliminating these films. FE should no longer be used to diagnose LI. Given the rare incidence of these injuries, MRI should be used when there is high clinical suspicion of injury.