Quantifying Progressive Anterior Overgrowth in the Thoracic Vertebrae of Adolescent Idiopathic Scoliosis Patients: A Sequential Magnetic Resonance Imaging Study.

STUDY DESIGN Anterior and posterior vertebral body heights were measured from sequential magnetic resonance imaging (MRI) scans of adolescent idiopathic scoliosis (AIS) patients and healthy controls. OBJECTIVE To measure changes in vertebral body height over time during scoliosis progression to assess how vertebral body height discrepancies change during growth. SUMMARY OF BACKGROUND DATA Relative anterior overgrowth has been proposed as a potential driver for AIS initiation and progression. This theory proposes that the anterior column grows faster, and the posterior column slower, in AIS patients when compared with healthy controls. There is a disagreement in the literature as to whether the anterior vertebral body heights are proportionally greater than posterior vertebral body heights in AIS patients when compared with healthy controls. To some extent, these discrepancies may be attributed to methodological differences. METHODS MRI scans of the major curve of 21 AIS patients (mean age 12.5 ± 1.4 years, mean Cobb 32.2 ± 12.8 degrees) and between T4 and T12 of 21 healthy adolescents (mean age 12.1 ± 0.5 years) were captured for this study. Of the 21 AIS patients, 14 had a second scan on average 10.8 ± 4.7 months after the first. Anterior and posterior vertebral body heights were measured from the true sagittal plane of each vertebra such that anterior overgrowth could be quantified. RESULTS The difference between anterior and posterior vertebral body height in healthy, nonscoliotic children was significantly greater than in AIS patients with mild to moderate scoliosis. There was; however, no significant relationship between the overall anterior-posterior vertebral body height difference in AIS and either severity of the curve or its progression over time. CONCLUSION Whilst AIS patients have a proportionally longer anterior column than nonscoliotic controls, the degree of anterior overgrowth was not related to the rate of progression or the severity of the scoliotic curve. LEVEL OF EVIDENCE 3.