Imbalance of electromyographic activity and physical rehabilitation of patients with idiopathic scoliosis.

In order to monitor changes in postural performance capacity in patients with idiopathic scoliosis after an intensive in-patient Schroth rehabilitation programme lasting several weeks, we undertook electromyographic investigations in 316 patients with a mean age of 20 years (range 8-76 years) and a mean Cobb curvature angle of 38.2 degrees (range 10 degrees-147 degrees). Electromyographic activity was recorded by means of surface electrodes in the thoracic and lumbar region at the level of the apical vertebra, paravertebrally on both sides of the erector spinae muscle during trunk lifting from the prone position. Two hundred and fifty-nine recordings without artefacts were evaluated. Significant reductions in muscle activity of 6.85% in the thoracic convex region (P < 0.05) and of 14.2% (P < 0.001) on the lumbar convex side were found. The activity quotient (convesx/concave) was reduced by 11.99% (P<0.001) in the thoracic region and by 7.91% (P<0.01) in the lumbar region. These findings confirm the improvement of postural performance capacity after an intensive in-patient Schroth rehabilitation programme. As the imbalance of electromyographic activity may be influenced by scoliosis-specific exercises leading to a highly significant reduction of the Cobb angle, it is assumed to be secondary to the development of the scoliotic curve and may not be a primary factor in the aetiology of idiopathic scoliosis.