The effect of spinal manipulative therapy on spinal range of motion: a systematic literature review

BACKGROUND: Spinal manipulative therapy (SMT) has been shown to have an effect on spine-related pain, both clinically and in experimentally induced pain. However, it is unclear if it has an immediate noticeable biomechanical effect on spinal motion that can be measured in terms of an increased range of motion (ROM). OBJECTIVE: To assess the quality of the literature and to determine whether or not SMT is associated with an immediate increase in ROM. DESIGN: A systematic critical literature review. METHOD: Systematic searches were performed in Pubmed, the Cochrane Library and EMBASE using terms relating to manipulation, movement and the spine. Selection of articles was made according to specific criteria by two independent reviewers. Two checklists were created based on the needs of the present review. Articles were independently reviewed by two reviewers. Articles were given quality scores and the data synthesized for each region treated in the literature. Findings were summarized in tables and reported in a narrative fashion. RESULTS: Fifteen articles were retained reporting on experiments on the neck, lumbar spine, hip and jaw. The mean quality score was 71/100 (ranges 33/100 - 92/100). A positive effect of SMT was reported in both studies where mouth opening was assessed after cervical manipulation. In five of the nine studies on cervical ROM a positive effect was reported, whereas the remaining four studies did not show improvement. None of the three studies of the lumbar spine showed an effect of SMT on lumbar ROMs and one study of sacroiliac manipulation reported no effect on the ROM of the hip joint. In relation to the quality score, the seven highest ranked studies, showed significant positive effects of SMT on ROM. Continuing down the list, the other studies reported no significant differences in the outcomes between groups. CONCLUSION: SMT seems sometimes to have a small effect on ROM, at least in the cervical spine. Further research should concentrate on areas of the spine that have the potential of actually improving to such a degree that a change can be easily uncovered.