Prognostic role of rib hump in overlying thoracic curve correction above selective fusion for lenke 5 idiopathic adolescent scoliosis

STUDY DESIGN: Prospective study.OBJECTIVE: To assess whether rib hump is a prognostic factor of final thoracic Cobb angle.SUMMARY OF BACKGROUND DATA: Correction of thoracolumbar/lumbar curve, preoperative thoracic curves angle, thoracic curves angle on bending, the thoracolumbar-lumbar angle/thoracic curves angle ratio, thoracic kyphosis, and growth stage influences spontaneous correction of uninstrumented thoracic curves angle above selective fusion for Lenke 5 Adolescent Idiopathic Scoliosis. Indeed, preoperative rib hump has never been expressly evaluated as a prognostic factor of final thoracic curves angle.METHODS: In total, 50 patients with Lenke 5 Adolescent Idiopathic Scoliosis, selectively instrumented with posterior construct were included. Two patients were lost to follow-up and 48 had follow-up ≥2 years. Demographic data, preoperative thoracic rib hump (measured in millimeter in trunk anteflexion), and radiologic spinal parameters were recorded preoperatively and at last consultation. T test was used to compare mean values, linear and logistic regressions to assess predictability of final thoracic curve angle.RESULTS: Main thoracolumbar-lumbar curve angle decreased from 47 degrees (range, 36-72 degrees) to 12 degrees at the final consultation (range, 1-28 degrees). Thoracic curves angle decreased from 26 degrees (range, 2-40 degrees) preoperatively to 16 degrees (range, 2-41 degrees) at the final consultation (P=0.001) (correction=37%). Preoperative rib hump was present in 10 patients. Final thoracic Cobb angle was 27 degrees (8-41 degrees) in patients with rib hump and 14 degrees (0-32 degrees) in patients without rib hump (P<0.001).Multiregression highlighted thoracic curves angle on bending (P=0.001), preoperative thoracic curves angle (P=0.011) and rib hump (P=0.012) as prognostic factors of higher final thoracic curves angle.CONCLUSION: Rib hump significantly influenced final thoracic curves angle.