Cobb angle progression in adolescent scoliosis begins at the intervertebral disc.
METHODS
Longitudinal radiographic study of patients with progressive idiopathic scoliosis.


OBJECTIVE
To determine the relative contributions of vertebral and disc wedging to the increase in Cobb angle during 3 phases of adolescent skeletal growth and maturation.


BACKGROUND
Both disc wedging and vertebral body wedging are found in progressive scoliosis, but their relative contribution to curve progression over time is unknown. Which occurs first is important for understanding how scoliosis progresses and for developing methods to halt progression. Previous studies have not properly identified maturity, and provide conflicting results.


METHODS
Eighteen girls were followed through their adolescent growth spurt with serial spine and hand skeletal age radiographs. Each Cobb angle was divided into disc wedge angles and vertebral wedge angles. The corresponding hand radiographs provided a measure of maturity level, the Digital Skeletal Age (DSA). The disc versus bone contributions to the Cobb angle were then compared during 3 growth phases: before the growth spurt, during the growth spurt and after the growth spurt. Significance of relative changes was assessed with the Wilcoxon 2-sided mean rank test.


RESULTS
Before the growth spurt, there was no difference in relative contributions of the disc and the bone (3 degrees vs. 0 degrees, P = 0.38) to curve progression. During the growth spurt, the mean disc component progressed significantly more than that of the vertebrae (15 degrees vs. 0 degrees, P = 0.0002). This reversed following the growth spurt with the vertebral component progressing more than the disc (10 degrees vs. 0 degrees, P = 0.01).


CONCLUSIONS
Adolescent idiopathic scoliosis initially increases through disc wedging during the rapid growth spurt with progressive vertebral wedging occurring later.
Will
Ryan E
RE
Shriners Hospitals for Children, Erie, PA, USA.
Stokes
Ian A
IA
Qiu
Xing
X
Walker
Matthew R
MR
Sanders
James O
JO
D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006128:Growth / Q000502:physiology; D006225:Hand / Q000000981:diagnostic imaging; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D008137:Longitudinal Studies; D008954:Models, Biological; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D013131:Spine / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology