An investigation into the production of intra-articular gas bubbles and increase in joint space in the zygapophyseal joints of the cervical spine following spinal manipulation in asymptomatic subjects

Abstract

Currently, no scientific evidence exits to demonstrate that radiolucent cavities, or an increase in joint space in the cervical zygapophyseal joints, occur following the manipulation of these joints. However, previous studies have demonstrated the presence of these phenomena in the metacarpophalangeal joints following the application of linear traction to these joints to the point of cavitation ('cracking'). This study was designed to determine whether such phenomena occurred in the cervical spine. Plain film and computed tomographic imaging were used for this purpose. It was hypothesized that an increase in joint space and a decrease in joint density (radiolucent cavity) would be demonstrable following the application of the manipulation in the non-traction and particularly the traction positions of the neck. Volunteers were screened for conformity with the inclusion criteria. Of these, 22 asymptomatic subjects were selected. The subjects were then assigned to one or two of 6 possible experimental groups. The subjects of each group were radiographically imaged before and immediately after the manipulation. In all cases except for Experiment 1 the subjects received : o a pre-manipulation X-ray and/or CT scan, o a pre-manipulation plus traction X-ray and/or CT scan, a post-manipulation X-ray and/or CT scan and o a post-manipulation plus traction X-ray and/or CT scan. A total of 83 CT scans consisting of 1660 images and 36 fluoroscopy-assisted plain-film radiographs were performed.