Open AccessParaspinal muscle morphology and composition in adolescent idiopathic scoliosis: A histological analysis
Author(s) -
Shahidi Bahar,
Yoo Andrew,
Farnsworth Christine,
Newton Peter O.,
Ward Samuel R.
Publication year - 2021
Publication title -
jor spine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.125
0ISSN - 2572-1143
DOI - 10.1002/jsp2.1169
Subject(s) - medicine , idiopathic scoliosis , anatomy , apex (geometry) , muscle fibre , scoliosis , deformity , pathology , skeletal muscle , surgery
Abstract Background Adolescent idiopathic scoliosis (AIS) is a condition resulting in spinal deformity and tissue adaptation of the paraspinal muscles. Although prior studies have demonstrated asymmetries in fiber type and other energetic features of muscle on the concave side of the curve, muscle morphology, architecture, and composition have not been evaluated. Therefore, the purpose of this study was to compare differences in paraspinal muscle microarchitecture and composition between concave and convex sides of a scoliotic curve in individuals with AIS. Methods Paraspinal muscle biopsies were obtained at the apex of the scoliotic curve in 29 individuals with AIS undergoing surgical deformity correction. Histological assays were performed to quantify fiber size, evidence of muscle degeneration and regeneration, and tissue composition (proportion of muscle, collagen, and fat). Differences between contralateral muscle samples were compared using two‐tailed paired Student's t tests, and relationships between clinical characteristics (age and curve severity) and muscle characteristics were investigated using Pearson correlations. Results Muscle fibers were significantly larger on the convex side of the curve apex ( P = .001), but were lower than literature‐based norms for healthy paraspinal muscle. There were no differences in amount of degeneration/regeneration ( P = .490) or the proportion of muscle and collagen ( P > .350) between the concave and convex sides, but high levels of collagen were observed. There was a trend toward higher fat content on the concave side ( P = .074). Larger fiber size asymmetries were associated with greater age ( r = .43, P = .046), and trended toward an association with greater curve severity ( r = .40, P = .069). Conclusions This study demonstrates that although muscle fibers are larger on the convex side of the scoliotic curve in AIS, muscles on both sides are atrophic compared to non‐scoliotic individuals, and demonstrate levels of collagen similar to severe degenerative spinal pathologies. These findings provide insight into biological maladaptations occurring in paraspinal muscle in the presence of AIS.