Diagnostic accuracy of flexion-extension radiography for the detection of ligamentous cervical spine injury following a normal cervical spine computed tomography.

BACKGROUND: Flexion-extension radiography (FER) has been utilised for the detection of ligamentous injury in patients who have been cleared of bony injury. Some studies call into question the diagnostic accuracy of FER, the high proportion of inadequate FER images and the adverse effects of prolonged cervical collar immobilisation although awaiting FER.

METHODS: We conducted a two-part retrospective study of trauma patients presenting to a trauma centre between January 2007 and December 2014. A cross-sectional analytic study was used to determine diagnostic accuracy and a case-control design was used to compare characteristics and complications of those having FER with similar patients not having FER. Inclusion criteria were age ≥16, blunt trauma mechanism, a normal computed tomography (CT) of the cervical spine and FER to assess for ligamentous injury. The reference standard was magnetic resonance imaging evidence of ligamentous disruption or a therapeutic intervention to treat ligamentous instability.

RESULTS: There were 176 participants meeting inclusion criteria. Studies were considered inadequate in 168 participants (95.5%). There were zero true positives, four false positives, 168 true negatives and four false negatives: sensitivity 0% (0.0-60.2%), specificity 97.7 (94.2-99.4%), positive predictive value 0% (0.0-60.2%) and negative predictive value 97.7 (94.2-99.4%). Participants having FER remained in cervical collars and in hospital longer than control patients. Complications of cervical collar use were uncommon.

CONCLUSION: FER does not contribute additional diagnostic accuracy for the detection of ligamentous injury to the cervical spine following a normal CT of the cervical spine. We recommend FER be removed from cervical spine clearance protocols.