Drooping of apical convex rib-vertebral angle in adolescent idiopathic scoliosis of more than 40 degrees: A prognostic factor for progression

STUDY DESIGN: It is a retrospective analysis on radiograms of 113 adolescent idiopathic scoliosis (AIS) patients with a curve of 40 degrees or more at the time of presentation. OBJECTIVES: Our aim was to find out the prognostic factor for the curve progression for this group. SUMMARY AND BACKGROUND: There is general consensus in favor of operation when the curve is more than 40 degrees for AIS. There are number of reports on the prognostic and etiologic factors for the progression of scoliosis. Rib-vertebral angle (RVA) became a topic of interest regarding the progression of scoliosis for many researchers since Mehta introduced it in 1972. METHODS: There were 113 AIS patients (95 females and 18 males) who had a curve of more than 40 degrees at the time of presentation, with an average age of 12 years and 10 months. We measured RVA on the convex and concave sides at the apex and 12th vertebrae and measured rib-vertebral angle difference (RVAD) using Mehta's method at each follow-up. We also measured the drooping value of the convex rib after bracing and at final follow-up. RESULTS: Of the 113 patients, 84 responded to bracing and in 29 the curve progressed despite bracing at final follow-up. The average drooping of rib at the apex on the convex side was 11 degrees, which progressed compared with 0.12 degrees in those who responded to treatment. On analyzing the results we could not find any relationship in 12th vertebrae but there was a significant relationship between the drooping value of convex apical rib (RVA Cx) after bracing and curve progression, which is similar to RVAD. There was no relationship between curve progression and initial angle, age, Risser sign, or menarchal status at presentation. CONCLUSIONS: From our study, we conclude that a large number of curves can be treated with bracing; however, when we notice drooping of the convex apical rib along with RVAD, the curve will likely progress.