A myoelectric model for thoracic spinal motion dynamics during clinical rotation tests: Part 1. Ipsilateral regional motor performance.

Osteopathic physicians may use regional diagnostic rotation tests of the spine during physical examinations for patient evaluations. Clinical judgments of these responses relate to symmetry as a criterion for mobility. This first part of a two-part study reports the authors' investigation of regional ipsilateral myoelectric activity during responses to active and passive shoulder and trunk rotations on the left- and right-side muscles with subjects seated. Results indicate symmetry existed in both active and passively induced regional rotation tests. Further, the distribution (profile) of ipsilateral myoelectric activity in the thorax reflected a bell-shaped activity curve that peaked at thoracic levels 6 and 7. This profile element demonstrates remarkable similarity between volitional and physician-induced rotation motions. These myoelectric data justify symmetry and profile as tangible standards for making clinical judgments of regional responses to spinal rotation diagnostic tests.