Lordoscoliosis in Adolescent Idiopathic Scoliosis: A MRI Study of the Thoracic Vertebrae vs. Normal Controls

¹The Chinese University of H. Kong
²The Hong Kong Polytechnic University, Hong Kong

PURPOSE:
The study is to investigate the abnormalities in the differential growth of the anterior and posterior column of the thoracic vertebrae in adolescents with idiopathic thoracic scoliosis Vs normal controls.

METHODS:
Whole Spine MRI was performed on 80 adolescent girls (12-15 years of age) with mild idiopathic scoliosis (Cobb's angle 20-40 degrees) and 22 age matched normal subjects. Multiple measurements of each thoracic vertebra were obtained from the best sagittal and axial MRI cuts. Independent t-test was used for analyzing the inter-group differences.

RESULTS:
1. In scoliosis patients, the anterior vertebral height and posterior height were significantly longer than in normal subjects without differences in the diameter. The height of the pedicles is significantly shorter (Table 1). 2. The differential growth between the anterior column and the posterior column of the thoracic spine in scoliosis patients was significantly different from that in normal subjects.
(Table 1)

CONCLUSION:
Comparing with age matched normal subjects, patients with idiopathic scoliosis has disproportional increased longitudinal growth of vertebral body, which occurs mainly through endochondral ossification. In contrast, the circumferential growth via membranous ossification is retarded in both the vertebral bodies and pedicles. Further studies on the abnormal regulatory mechanism of coupling of membranous and endochondral ossification may help in further understanding of the etiology and pathogenesis of adolescent idiopathic scoliosis.

Table 1: MRI measurements of thoracic vertebra

*Acknowledgement of SRS Etiology Grant support 1999/20