Associations between neck and shoulder pain (called katakori in Japanese) and sagittal spinal alignment parameters among the general population.

BACKGROUND Neck and shoulder pain (NSP), called katakori in Japanese, is one of the most common medical symptoms in the Japanese population; however, the pathogenesis of NSP has not yet been adequately elucidated. The purpose of this study was to investigate the associations between NSP and sagittal spinal alignment among the general population in Japan. MATERIALS AND METHODS Medical examinations were conducted in the northeast village of Gunma, Japan. A questionnaire regarding NSP was distributed among 329 Japanese subjects (125 men and 204 women). Regarding the prevalence of NSP, the participants were asked to report the occurrence of NSP over the previous two weeks. For each participant, the parameters for sagittal spinal alignment, including thoracic kyphosis angle, lumbar lordosis angle, and spinal inclination relative to a perpendicular line, were measured with a SpinalMouse(®) (Idiag, Vplkerswill, Switzerland), an electronic computer-aided measuring device. We investigated the associations between the prevalence of NSP and the parameters obtained with the SpinalMouse(®). Statistical analyses were performed using Student's t test, Welch's t test, the chi-squared test, and a multivariate logistic regression analysis. A P value of 0.05 was considered to be statistically significant. RESULTS The prevalence of NSP within the two weeks prior to questioning was 52.0 % (171 of 329 subjects). The subjects in the NSP group were significantly younger than those in the non-NSP group. There was a significant gender difference between the NSP group and the non-NSP group, as significantly more females complained of NSP than males. No significant association between the thoracic kyphosis angle and NSP was observed. However, the lumbar lordosis angles measured in the subjects in the NSP group were significantly larger than those in the non-NSP group, and the inclinations relative to a perpendicular line measured in the subjects in the NSP group were significantly larger than those in the non-NSP group. Furthermore, we performed a logistic regression analysis on each factor that showed a significant difference; age, gender, and the lumbar lordosis angle were each found to be significant. CONCLUSIONS We investigated the associations between NSP and spinal sagittal alignment using the SpinalMouse(®) system, and demonstrated that some spinal alignment parameters are associated with NSP.