Comparative study of the spinopelvic alignment in the patients with idiopathic lumbar scoliosis between adulthood and adolescence.

Abstract

BACKGROUND\nUnderstanding the natural history of the spinopelvic alignment in adolescent idiopathic scoliosis (AIS) is important in developing surgical strategies for patients with adult idiopathic lumbar scoliosis (AdLS). However, since it is challenging to follow individuals without any treatments, we sought to estimate its natural history by comparing radiographic characteristics of patients with AIS and AdLS.\n\n\nMETHODS\nWe included patients with Lenke 5 AIS and patients with AdLS, who were diagnosed with Lenke 5 AIS in adolescence. The Cobb angle of the curve and spinopelvic parameters were measured by whole spine radiographs. The AdLS patients were divided into two groups according to age <50 years (AdLS<50) or ≥50 years (AdLS≥50). Radiographic parameters were compared among the AIS, AdLS<50, and AdLS≥50 groups. The relationship between age and each parameter was analyzed using nonlinear regression analysis.\n\n\nRESULTS\nWe analyzed 40 patients with AIS (all female, mean age 16.8 ± 3.2 years) and 35 patients with AdLS (34 female and one male, mean age 55.4 ± 12.1 years). Thoracolumbar/lumbar curve and thoracolumbar kyphosis was significantly greater in the AdLS<50 group compared with the AIS group, without progression after age 50 years. Lumbar lordosis and pelvic tilt deteriorated linearly with age. AIS and AdLS<50 patients maintained sagittal balance, which deteriorated in AdLS≥50 patients.\n\n\nCONCLUSIONS\nOur results may predict the following natural course of Lenke 5 AIS: (1) progression of scoliotic deformity of thoracolumbar/lumbar curve with increased thoracolumbar kyphosis; (2) subsequent lumbar hypolordosis followed by pelvic retroversion; and (3) sagittal imbalance after failure of compensation.