Cervical spine disorders in farm workers requiring neck extension actions

Background Cervical extension is considered a risk factor for provoking radicular and spinal cord compromise. However, there have been no reports on the relation between extension strain (ES) and cervical spine disorders: degenerative cervical spine disorders, dynamic canal stenosis (DCS), and cervical myelopathy. We performed a cross-sectional study to investigate the relation. Methods Orthopedic examinations were performed on 177 grape-growers (ES-exposed group) and 191 eggplant-growers (control group) between May and August 2000; and patients with degenerative cervical spine disorders, DCS, and cervical myelopathy were identified in the two groups. ES, degenerative cervical spine disorders, DCS, and cervical myelopathy were regarded as exposure variables; and age, sex, and working years were regarded as confounders. In cases where the subject was exposed to each exposure variable, multivariate-adjusted odds ratios to degenerative cervical spine disorders, DCS, and cervical myelopathy and multivariate-adjusted odds ratios regarding cervical myelopathy as the dependent variable were calculated by unconditional logistic regression analysis. Results Multivariate unconditional logistic regression analysis showed a significant odds ratio of ES to degenerative cervical spine disorders 2.72, 95% confidence interval (CI) 1.62–4.56]. Multivariate unconditional logistic regression analysis showed significant odds ratios for DCS (4.50, 95% CI 2.03–9.96) and age (1.07, 95% CI 1.01–1.14) regarding cervical myelopathy as the dependent variable. Conclusions These findings suggested that ES of the cervical spine is a risk factor for degenerative cervical spine disorders, and DCS and the aging process are risk factors for cervical myelopathy.