Motor Control Changes in Trunk Muscles after Using Anatomical Posture Control Orthosis in the Elderly Hyperkyphotic Subjects

Abstract

Introduction: Hyperkyphosis is known to interfere with the normal function of the trunk musculature in the elderly. Although the effectiveness of orthoses in improving posture and balance in hyperkyphotic elderly people has received much attention, the effect of an orthosis on motor control of muscles remains unknown. This study aimed to evaluate changes in motor control strategies of trunk muscles during walking in elderly hyperkyphotic subjects after using an anatomical posture control (APC) orthosis. Materials and Methods: A total of 19 elderlies (11 women  and  8  men)  with  thoracic hyperkyphosis of more than 45 degrees were enrolled in the study. Surface electromyography (EMG) signals were recorded from 6  trunk  muscles  bilaterally  with and without orthosis. The voluntary response index (VRI) was calculated from quantitative analysis of surface electromyography (sEMG) data during level walking in those with and without orthosis. The outcome variables of VRI included the similarity index (SI) and electromyographic magnitude (MAG) of muscle groups. The effects of APC orthosis on trunk motor control were tested using a Wilcoxon non-parametric test. Cohen’s d effect sizes were also calculated. Results: A significant improvement was observed (P<0.05) in MAG and response vector (RV) of five muscles from the right and left sides and the VRI increased significantly after using this posture control orthosis (P<0.05; effect size [ES]: 0.27). Conclusion: Improving trunk motor control after using orthosis, with relatively medium effect sizes, was observed in the elderly with hyperkyphosis during walking.