Effective diagnosis of pelvic asymmetry based on correlation with idiopathic scoliosis

Correlation analysis between scoliosis and pelvic asymmetry of adolescent idiopathic scoliosis patients were studied by measuring inclination angle, pressure distribution, and electromyography. 42 subjects were classified into six groups including control group, asymmetry on the left pelvis group, asymmetry on the right pelvis group, scoliosis group, scoliosis with asymmetry on the left pelvis group, and scoliosis with asymmetry on the right pelvis group. And then, they performed anterior, posterior, and left-right pelvic tilling while sitting on the balance board system for 5 seconds to assess their postural balance. Inclination and obliquity angles between the groups were measured by an accelerometer located on the system. Pressure distribution (maximum force and peak pressure) was analyzed using a seat sensor system. In addition, surface electrodes were attached to the external oblique, thoracic erector spinae, lumbar erector spinae, and lumbar multifidus muscles of each participant. In this study, inclination and obliquity angles increased more asymmetrically in participants with both pelvic asymmetry and scoliosis than with pelvic asymmetry or scoliosis alone. Maximum forces and peak pressures of each group showed an unbalanced pressure distribution caused by the difference in height between both pelvis as well as curve type of the patients' spines when performing anterior, posterior, left, and right pelvic tilting while sitting. Muscle activity patterns of the abdominal and erector spinae muscles may be influenced by spine curve type and region of idiopathic scoliosis. Asymmetrical muscle contraction patterns were observed on the convex side of scoliotic patients and these muscle activity patterns were changed by the pelvic asymmetry. From these results, it was concluded that pelvic asymmetry and idiopathic scoliosis cause postural asymmetry, unequal weight distribution, and muscular imbalance during sitting. Furthermore, sitting balance measurement system can provide comfortable and easy to use environment for patients to monitor their posture consistently in daily life.