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.