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Abstract Background Adolescent idiopathic scoliosis (AIS) refers to a three‐dimensional spinal deformity which has a typical onset during adolescence. In most cases, the cause of the deformity cannot be clearly identified. Unbalanced paraspinal muscle activity in AIS patients was reported and hypoxia was implicated to regulate myogenesis. This study aims to investigate the association between myogenesis/muscle toning and HIF‐αs activity in the pathogenesis of AIS. Methods HIF‐αs expression was examined by enzyme‐linked immunosorbent assay and western blot in paraspinal myoblasts isolated from 18 subjects who underwent deformity correction surgery. QPCR was conducted to measure the gene expression levels of perinatal muscle fiber markers MYH3, MYH8; slow twitch muscle fiber markers MHY7; fast twitch muscle fiber markers MYH4; and myogenic regulatory factors MYF5 and MYOG. Slow and fast twitch muscle fiber composition in concave/convex paraspinal musculature of AIS subjects was evaluated by immunostaining of myosin heavy chain type I (MyHC I) and myosin heavy chain type II (MyHC II). Results Reduced HIF‐2α induction under hypoxia was found in paraspinal myoblast culture of 33% AIS subjects. We detected a suppression of perinatal and slow twitch muscle fiber associated genes, but not fast twitch muscle fiber‐associated genes and myogenic regulatory factors in HIF‐2α misexpressed AIS myoblasts. Distinct reduction of slow twitch muscle fiber was evidenced in convex paraspinal musculature, suggesting an asymmetric expression of slow twitch muscle fiber in HIF‐2α misexpressed AIS patients. Conclusions This study indicates an association of abnormal HIF‐2α expression in paraspinal myoblasts and a disproportionate slow twitch muscle fiber content in the convexity of the curvature in a subset of AIS subjects, suggesting HIF‐2α dysregulation as a possible risk factor for AIS. The role of HIF‐2α in paraspinal muscle function during spinal growth and its relevance in AIS prognosis warrants further investigation.

Abstract Lumbar disc‐displacement, Modic changes (MCs), and UTE Disc Sign (UDS) on MRI are clinically relevant spinal phenotypes that can lead to sciatica/LBP. Not all degenerated discs result in disc‐displacement, MCs and UDS, suggesting varied etiologies. Spinopelvic parameters have been implicated in various spinal disorders. Pelvic incidence (PI) is “fixed parameter” since skeletal maturity. No study has addressed disc‐displacement, MCs and UDS in context of spinopelvic parameters. Therefore, the aim of study was to determine if spinopelvic parameters are associated and predict clinically‐relevant MRI‐phenotypes. One hundred and eight population‐based subjects (mean age: 52.3 years) were recruited. Spondylolisthesis and scoliosis individuals were excluded. Lumbar lordosis (LL), PI, sacral slope (SS), and pelvic tilt (PT) were assessed on lateral plain radiographs. Disc degeneration was assessed and summated, and presence or not of disc‐displacement and MCs were noted on T2W MRI. UDS was detected on UTE. Following exclusion criteria, 95 subjects were assessed. Disc‐displacement (82.1%), MCs (52.6%), and UDS (37.9%) were associated with lower PI, SS, LL, and LL/PI index. On multivariate analyses, lower PI was significantly related to development of these MRI phenotypes (adjusted OR range:0.95‐0.92; P