Are there gender differences in sagittal spinal pelvic inclination before and after the adolescent pubertal growth...

Significant progression of spinal deformity could occur during the peak of pubertal growth in adolescent idiopathic scoliosis (AIS). Gender differences in spinal and vertebral inclination have been reported in asymptomatic young adults and are thought to affect the risk of curve progression in male and female AIS. The present study aimed to investigate whether there were gender differences in the sagittal spinal-pelvic profile and whether any differences occurred before or developed during the normal pubertal growth spurt.

The sagittal up-right standing spine X-ray films from 71 male and 82 female asymptomatic adolescents were collected. The inclination of the global spine was analyzed by measuring the spino-sacral angle (SSA) and the spinal tilt (ST). Additionally, the inclination of the vertebrae (T1-L5), thoracic kyphosis (T4-T12) and lumbar lordosis were measured. These subjects were divided into the ascending phase (non-fused triradiate cartilage) G1 subgroup, the peak (fused triradiate cartilage and Risser grade 0-1) G2 subgroup and the late phase (Risser grade 2-5) of pubertal growth G3 subgroup. The comparisons between the males and females were carried out within the subgroups.

In the subgroups G1 and G2, the females showed a trend of less ventral inclination in the upper thoracic vertebrae (T1-T5) and greater dorsal inclination in the lower thoracic vertebrae (T7-T12), although the differences were not statistically significant. In the G3 subgroup, the females showed significantly larger SSA (133.7° ± 4.5° vs. 128.4° ± 4.0°), ST (96.3° ± 2.6° vs. 94.8° ± 3.4°) and dorsal inclination of T1 and T12-L2 than did the males (p < 0.05).

Although a trend toward a more backward inclination of the spine and individual vertebrae might pre-exist during the ascending phase or peak of pubertal growth, the differences become more significant during the late stage of puberty. The observation could be related to relatively active anterior vertebral overgrowth that occurs in females during pubertal growth.