Decreased cortical bone density and mechanical strength with associated elevated bone turnover markers at peri-pubertal peak height velocity: a cross-sectional and longitudinal cohort study of 396 girls with adolescent idiopathic scoliosis.

Abstract

As part of the studies related to aetiopathogenesis of AIS, we assessed bone qualities, bone mechanical strength and bone turnover markers (BTMs) focusing at the peri-pubertal period and PHV in AIS girls. 396 AIS girls in two separate cohorts were studied. Skeletal maturity was assessed using the validated thumb ossification composite index (TOCI). Bone qualities and strength were evaluated with high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA). Cohort-A included 179 girls (11.95 ± 0.95years old). Girls at TOCI-4 had numerically the highest height velocity (0.71 ± 0.24cm/month) corresponding to the PHV. Subjects at TOCI-4 had lower cortical volumetric BMD (672.36 ± 39.07mg/mm3), cortical thickness (0.68 ± 0.08mm) and apparent modulus (1601.54 ± 243.75N/mm2) than: (a) those at TOCI-1-3 (724.99 ± 32.09mg/mm3 (p < 0.001), 0.79 ± 0.11mm (p < 0.001) and 1910.88 ± 374.75N/mm2 (p < 0.001), respectively) and (b) those at TOCI-8 (732.28 ± 53.75mg/mm3 (p < 0.001), 0.84 ± 0.14mm (p < 0.001), 1889.11 ± 419.37N/mm2 (p < 0.001), respectively). Cohort-B included 217 girls (12.22 ± 0.89years old). Subjects at TOCI-4 had higher levels of C-terminal telopeptide of type 1 collagen (1524.70 ± 271.10pg/L) and procollagen type 1N-terminal propeptide (941.12 ± 161.39µg/L) than those at TOCI-8 (845.71 ± 478.55pg/L (p < 0.001) and 370.08 ± 197.04µg/L (p < 0.001), respectively). AIS girls had decreased cortical bone density and bone mechanical strength with elevated BTMs at PHV. Coupling of PHV with decreased cortical and FEA parameters could provide the link to the previously reported observation that low BMD could contribute as one of the prognostic factors for curve progression that mostly occurs during PHV in AIS.