Sagittal alignment of the spine and pelvis during growth.

STUDY DESIGN

Prospective study of the sagittal plane alignment of the spine and pelvis in the normal pediatric population.

OBJECTIVES

To document the sagittal alignment of the spine and pelvis and its change during growth in the normal pediatric population.

SUMMARY OF BACKGROUND DATA

Pelvic morphology as well as sagittal alignment of the spine and pelvis in the pediatric population are poorly defined in the literature.

METHODS

Five parameters were evaluated on lateral standing radiographs of 180 normal study participants 4 to 18 years of age: thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. Statistical analysis was performed using two-tailed Student t tests and Pearson's coefficients (level of significance = 0.01).

RESULTS

The mean thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence values were 43.0 degrees, 48.5 degrees, 41.2 degrees, 7.2 degrees and 48.4 degrees, respectively. There was no significant difference between males and females. Thoracic kyphosis, lumbar lordosis, pelvic tilt, and pelvic incidence were found to be weakly correlated with age, while sacral slope remained stable with growth.

CONCLUSIONS

Pelvic morphology, as measured by the pelvic incidence angle, tends to increase during childhood and adolescence before stabilizing into adulthood, most likely to maintain an adequate sagittal balance in view of the physiologic and morphologic changes occurring during growth. Pelvic tilt and lumbar lordosis, two position-dependent parameters, also react by increasing with age, most likely to avoid inadequate anterior displacement of the body center of gravity. Sacral slope is achieved with the standing posture and is not further significantly influenced by age. These results are important to establish baseline values for these measurements in the pediatric population, in view of the reported association between pelvic morphology and the development of various spinal disorders such as spondylolisthesis and scoliosis.