X-ray of trunk rotation

To establish the mechanism of the thoracolumbar spine during trunk rotation and its restriction.

Patients with one-sided rotation restriction were examined seated on a chair with the pelvis fixed in neutral position, at maximum right and left trunk rotations, before and after mobilization of movement restriction; anteroposterior X-rays were taken with a horizontal beam on a vertical X-ray cassette.

University neurology clinic.

Assessment of rotation and side bending of the thoracolumbar spine (a) on the normal and the restricted side and (b) after mobilization.

In all cases, there was both (coupled) rotation and side flexion during side bending, except that the thoracolumbar junction was frequently near midline; in such cases, the thoracic spine above was bent in the opposite direction. Both rotation and side-bending started at L5 and continued gradually in a cranial direction without a noticeable maximum at any level.

Although it is generally assumed that the configuration of the lumbar zygapophyseal joints precludes axial rotation in the lumbar spine, I find that, during trunk rotation, a coupled movement of side bending and rotation takes place in the lumbar spine and continues without a noticeable break into the thoracic spine. The site of movement restriction, which usually seems to be located at the thoracolumbar junction, cannot be visualized on X-rays.