Correction of scoliosis by muscle stimulation: biomechanical analyses.

Quantitative theoretical analyses of the ability of trunk muscle contraction forces to reduce lateral curves in the spine are presented. The effects of contraction of each of 68 muscle slips on each of 13 configurations of scoliosis were examined using biomechanical models of the trunk. The lateral curve, sagittal curve, and longitudinal axis rotation changes that resulted from contraction of these muscles were determined in each case. The muscles best able, from a biomechanical viewpoint, to reduce different lateral curves are listed. Effects of initial postural configurations and the consequences of reflex attempts to right the trunk after contracting a trunk muscle are described. Substantial changes in spine configuration can result from trunk muscle contractions of even modest intensity.