The straight cervical spine: does it indicate muscle spasm?

The loss of cervical lordosis in radiographs of patients presenting with neck pain is sometimes ascribed to muscle spasm. We performed a cross-sectional study of the prevalence of 'straight' cervical spines in three populations: 83 patients presenting to an accident department with acute neck pain, 83 referred to a radiology department with chronic neck problems, and 80 radiographs from a normal population survey carried out in 1958. Curvature was assessed on lateral radiographs both subjectively and by measurement. The prevalence of 'straight' cervical spines was 19% in the acute cases and 26% in the chronic cases. The 95% confidence interval for the difference was -6.4% to +19.3%. In the normal population 42% showed a straight spine, but a further third of these films had been taken in a position of cervical kyphosis; this probably reflects a difference in positioning technique. Women were more likely than men to have a straight cervical spine, with an odds ratio of 2.81 (95% CI 1.23 to 6.44). Our results fail to support the hypothesis that loss of cervical lordosis reflects muscle spasm caused by pain in the neck.