Abstract: BACKGROUND: At present, there is a lack of research on paraspinal electromyography in adolescent idiopathic scoliosis, so there is an urgent need for related research to improve the theoretical system of paraspinal electromyography in patients with scoliosis.  
OBJECTIVE: To analyze electromyographic changes of paraspinal muscles on both sides of the spine in adolescent idiopathic scoliosis patients in a resting state and standing position, and analyze the correlation of electromyography ratio of paraspinal muscles on convex and concave sides with Cobb angle, apical vertebra translation, and coronal balance distance.
METHODS:  A total of 21 adolescent idiopathic scoliosis patients were selected from the Scoliosis Clinic of Tianjin Hospital. Root mean square values of paraspinal muscles on both sides of the spine were recorded by Canadian T7550 surface electromyography in a resting state and standing position. The correlation between its variation and coronal plane parameters in patients with scoliosis was analyzed. The protocol complied with the Declaration of Helsinki and the relevant ethical requirements of Tianjin Hospital. The patients and guardians participating in the research had informed consent to the test and the trial process.  
RESULTS AND CONCLUSION: (1) Root mean square values of the convex side of the main curve and the concave side of the adolescent idiopathic scoliosis patients in the standing position and resting state were significantly different (P=0.005). Root mean square values of the convex side of the main curve were greater than those of the concave side, and the root mean square values of the convex side of the apical cone were significantly greater than those of the concave side. (2) There was a strong positive correlation between root mean square ratio of convex-concave side and Cobb angle in patients in standing and resting state (r=0.620, P=0.003); there was a moderate correlation with apical vertebra translation (r=0.443, P=0.044); however, there was a correlation with coronal plane equilibrium distance (r=-0.430, P=0.052). (3) These results indicate that in patients with adolescent idiopathic scoliosis, the tension of paravertebral muscles on the concavo-convex side was obviously unbalanced when maintaining a standing position, and the tension on the convex side was stronger, which was most obvious in the apical cone region. The ratio of root mean square on the concave-convex side of paravertebral muscles in patients with adolescent idiopathic scoliosis in standing and resting states increased with the increase of Cobb angle and apical vertebra translation. As scoliosis increases and the cone offset increases, the difference in the muscle tension required to maintain the trunk in an upright position becomes more pronounced.

Key words: adolescent idiopathic scoliosis, paraspinal muscle, surface electromyography, coronal plane parameters, correlation, Cobb angle, apical vertebra translation, coronal balance