Cervical spine imaging in trauma patients: a simple scheme of rationalising arm traction using zonal divisions of the vertebral bodies.

OBJECTIVE--To evaluate the effectiveness of arm traction for cervical spine imaging in trauma patients and devise a scheme to predict the probability of visualising the C7/T1 level in trauma patients. METHODS--98 trauma patients were studied. Each vertebral body was divided into three equal horizontal zones, the disc space between vertebral bodies being equivalent to one zone. The fifth cervical vertebra was used as the starting level (zone 1). Zones obtained pre and post arm traction on the lateral cervical spine radiographs were recorded. Results were analysed to show the probability of imaging the lower cervical spine, including the cervico-thoracic junction. RESULTS--If the initial film showed less than zone 10 (mid-C7 vertebra), the probability of showing zone 13 (upper body of T1) with arm traction was only 7.7%, that is, one success in every 13 pulls; or conversely, 12 failures in every 13 pulls. CONCLUSIONS--Unless an initial cervical spine radiograph includes the upper one third of the body of the C7 vertebra, the probability of attaining the C7/T1 level with arm traction is < 15%. It is suggested that all initial radiographs of the lateral cervical spine in major trauma patients be done with arm traction, and where the upper one third of the body of C7 vertebra is not seen, then computerised tomography, swimmer's, or oblique views be considered.