Classification system of the normal variation in sagittal standing plane alignment: a study among young adolescent boys.

Study Design: Cohort study.
Objective: To construct a sagittal standing alignment classification system in which the clinical significance of identified subgroups was considered with spinal pain measures.
Summary of Background Data: Numerous grading systems for the categorization of sagittal standing alignment have been devised. However, no common consensus exists about which typology should be adopted. Furthermore, the clinical significance of proposed classification schemes has rarely been assessed in terms of their relationship with spinal pain. Given the importance of the adolescent period for musculoskeletal development, research within a young adolescent population is required.
Methods: The study population consisted of 639 prepeak height velocity boys (mean age, 12.6 yr [standard deviation, 0.54 yr]). Sagittal posture was quantified during habitual standing; data were used to develop a classification system according to 3 gross postural and 5 lumbopelvic characteristics. Prevalence rates of spinal pain measures (pain and seeking care) were compared between postural subgroups.
Results: Cluster analysis indicated 3 types of characteristic overall sagittal profiles: neutral global alignment (n = 266 [41.6%]), sway-back (n = 199 [31.1%]), and leaning-forward (n = 174 [27.2%]). Within each of these categories, postural subgroups could be established according to specific lumbopelvic features. Logistic regression revealed that prevalence (lifetime and month) of low back pain and neck pain was significantly higher in boys classified as having sway-back posture than in those classified as having neutral global alignment. Spinal pain measures did not differ between groups of the lumbopelvic subclassification.
Conclusion: Meaningful classifications exist for sagittal plane posture in young adolescent boys, both on gross body segment and lumbopelvic level. In terms of clinical importance, that is, low back pain and neck pain prevalence, postural subgrouping strategies based on the orientation of gross body segments are suggested to be superior when compared with lumbopelvic grading.