Gait analysis in idiopathic scoliosis before and after surgery: a comparison of the pre- and postoperative muscle activation pattern.

In a prospective experimental study the level gait activity scores of the iliocostalis lumborum, glutaeus medius, tensor fasciae latae, vastus lateralis and peronaeus longus muscles of both body sides were examined by computerized electromyography in 23 patients with idiopathic scoliosis before and after CD instrumentation. The pre- and postoperative findings were examined as to asymmetric patterns in muscle requisition during gait and the respective changes induced by the spinal correction. These results were compared with the corresponding results obtained in healthy subjects in two independent sessions with identical experimental conditions. A muscle activity asymmetry coefficient was defined to quantify the degree of left/right muscle activation asymmetry observed. Postoperatively a statistically significant reduction (P < 0.05) of a preoperatively strongly increased activity was found in the lumbar muscles of the convex side of double major scolioses as well as in the glutaeus medius and tensor fascia lata muscles of the concave side of thoracic curvatures. Both the casuistic and statistical analysis of the results of our study support the hypothesis that activity asymmetries observed in the paravertebral musculature in idiopathic scoliosis patients are the result of the scoliotic body deformities, with consequent asymmetries in the biomechanical force patterns of body postures and body motions, rather than an aetiological factor of scoliotic curvatures.