Bone Abstracts

Objective: Grip strength is a marker of muscle mass which can optimize bone strength during puberty. While previous studies have shown AIS girls had poor bone qualities and mechanical properties when compared with non-AIS girls, the correlation between bone qualities and handgrip strength in AIS remains undefined. This study aimed to investigate the correlation between handgrip strength and bone qualities including volumetric bone mineral density (vBMD), bone geometry, trabecular micro-architecture and bone mechanical properties in girls with adolescent idiopathic scoliosis (AIS) versus age- and gender-matched normal controls.

Methods: 212 AIS girls and 247 controls aged 12 to 14 years old were recruited. Maximum handgrip strength was measured by dynamometer and bone qualities of non-dominant distal radius were measured by high-resolution peripheral quantitative computed tomography (HR-pQCT). Trabecular plate and rod structure was evaluated by Individual Trabecula Segmentation (ITS) and bone mechanical properties with Finite Element Analysis (FEA). Partial correlation was used to control confounding from age, height and weight.

Results: After adjusted for confounders, positive correlation between handgrip strength and bone geometry (including cortical area, trabecular area and cortical thickness) was detected in both AIS girls and controls (all P<0.05). In contrast, positive correlations between handgrip strength and cortical and trabecular vBMD, trabecular plate structure (including pBV/TV, pTb.N, P-P Junc. D. and P-R Junc. D) by ITS were only seen in AIS girls (p ranged from 0.003 to 0.015) but not in controls. Stiffness and failure load by FEA were positively correlated with handgrip strength in both AIS and controls.

Conclusions: Handgrip assessment can be useful for predicting bone qualities in AIS. Unique correlation patterns between bone qualities and handgrip strength were seen in AIS when compared with controls suggesting the characteristic muscle-bone cross talk in AIS could play a role in the etiopathogenesis of AIS. Further longitudinal studies are warranted to investigate the relationship between muscle strength, bone qualities and curve severity and the therapeutic implications.

Acknowledgement

This study is supported by RGC of HKSAR (468809 and 468411) and NIH grants (AR051376 and AR058004).

Disclosure: The authors declared no competing interests.