Classification of sagittal thoraco-lumbo-pelvic alignment of the adolescent spine in standing and its relationship to low back pain

Study Design. A prospective study of the sagittal standing posture of 766 adolescents. Objective. To determine whether posture subgroups based on photographic assessment are similar to those used clinically and to previous, radiographically determined subgroups of sagittal standing posture, and whether identified subgroups are associated with measures of spinal pain. Summary of Background Data. Relatively little research has been performed toward a classification of subjects according to sagittal spinal alignment. Clinical descriptions of different standing posture classifications have been reported, and recently confirmed in a radiographic study. There is limited epidemiological data available to support the belief that specific standing postures are associated with back pain, despite plausible mechanisms. As posture assessment using radiographic methods are limited in large population studies, successful characterization of posture using 2-dimensional photographic images will enable epidemiological research of the association between posture types and spinal pain. Methods. Three angular measures of thoraco-lumbo-pelvic alignment were calculated from lateral standing photographs of subjects with retro-reflective markers placed on bony landmarks. Subgroups of sagittal thoracolumbar posture were determined by cluster analysis of these 3 angular measures. Back pain experience was assessed by questionnaire. The associations between posture subgroups and spinal pain variables were evaluated using logistic regression. Results. Postural subtypes identified by cluster analysis closely corresponded to those subtypes identified previously by analysis of radiographic spinal images in adults and to those described clinically. Significant associations between posture subgroups and weight, height, body mass index, and gender were identified. Those adolescents classified as having non-neutral postures when compared with those classified as having a neutral posture demonstrated higher odds for all measures of back pain, with 7 of 15 analyses being statistically significant. Conclusion. Meaningful classifications exist for adolescent sagittal thoraco-lumbo-pelvic alignment, and these can be determined successfully from sagittal photographs. More neutral thoraco-lumbo-pelvic postures are associated with less back pain.