Scoliosis, or a lateral curvature of the spine, occurs in about 3% of adolescents. The etiology of most scoliosis is unknown. Clinically, it can be difficult to predict whether or not a scoliosis will progress during periods of rapid growth. This is true even in congenital scoliosis due to hemivertebrae where the etiology is known. If we knew why some curves progress, while others do not progress, than diagnostic and conservative treatment procedures could be substantially improved. The goal of this research is to gain insight into the mechanics of curve progression where the etiology is clearly skeletal. The neuromuscular system is the system primarily responsible for the mechanical control of spine configuration and symmetry via the epi-axial musculature. Yet, little is known about how this important, but complex, system responds in spatiotemporal terms to the emergence of a scoliosis. This spatiotemporal response will be quantified in a dog model using serial myoelectric and histological studies of the paravertebral muscles. These will be performed at multiple vertebral levels before, during, and after a lumbar scoliosis is initiated at different rates. The effect on the response of animal growth and changes in intervertebral disc stiffness will also be studied. Trends in these results will be compared with results of prospective myoelectric studies in children with progressive and non-progressive congenital scoliosis due to one or more hemivertebrae. Biomechanical models will be used to interpret the experimental data and gain insight into the determinants of curve progression. The data will provide a useful basis for studying paravertebral muscle activity patterns in the more frequent idiopathic form of scoliosis in which neuromuscular factors may or may not be involved.
