Paraspinal muscle morphology and composition in adolescent idiopathic scoliosis: A histological analysis

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.

Risk Factors, Lifestyle and Prevention among Adolescents with Idiopathic Juvenile Scoliosis: A Cross Sectional Study in Eleven First-Grade Secondary Schools of Palermo Province, Italy

“…Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine in the three planes of space [ 1 , 2 , 3 ]. Its prevalence is between 0.47% and 5.2%, with an incidence of the disease equal to 2–3% in the general population and a female/male ratio equal to 4:1 [ 4 ].…”

Role of Paravertebral muscle myostatin upregulation in the development of idiopathic scoliosis

“…In parallel with the in vitro results, MSTN upregulation resulted in severe oxidative stress, increased apoptosis, and abnormal myogenesis in mouse PVMs (Fig 6). These were the same PVM pathological features observed in IS patients (Li et al ., 2019a; Shahidi et al , 2021). Nevertheless, only mild necrosis was shown in bi-MSTN-OE mice, which may be associated with the slight scoliosis observed.…”

Evaluation of Symmetrical Exercises in Scoliosis by Using Thermal Scanning

“…Thus, on the concave side are arranged more type II fibers while on the convex side are predominant type I muscle fibers [27]. Recent studies also show that paraspinal muscles on both the concave and convex sides suffer from atrophy and collagen levels in the tissues are low, similar to degenerative pathologies [28][29][30].…”