The objective of this study was to retrieve, appraise, and synthesize the results of studies on the prevalence of active and latent myofascial trigger points (MTrPs) in subjects with spinal pain disorders. The databases PubMed, Embase, and CINAHL were searched, with no date or language restrictions. Search terms included controlled and free-text terms for spinal disorders and MTrPs. Further searches were conducted in Google Scholar and by contacting 3 experts in the field. Citation tracking of eligible studies was performed. Two reviewers independently selected observational studies assessing the prevalence of active and/or latent MTrPs in at least 1 group of adults with a spinal disorder. Twelve studies met the eligibility criteria. Methodologic quality was assessed by 2 reviewers independently using a modified version of the Downs and Black checklist. Two reviewers also used a customized form to extract studies and subjects’ characteristics and the proportions of subjects with active and/or latent MTrPs in each muscle assessed. A meta-analysis was performed when there was sufficient clinical homogeneity in at least 2 studies for the same spinal disorder. The Grading of Recommendations Assessment, Development and Evaluation approach was used to rate the body of evidence in each meta-analysis. A qualitative description of the results of single studies was provided. Low-quality evidence underpinned pooled estimates of MTrPs in the upper-body muscles of subjects with chronic neck pain. The point prevalence of MTrPs in different muscles of other disorders (eg, whiplash-associated disorders, nonspecific low back pain) was extracted from single studies with low methodologic quality and small samples. Active MTrPs were found to be present in all assessed muscles of subjects diagnosed with different spinal pain disorders. Latent MTrPs were not consistently more prevalent in subjects with a spinal disorder than in healthy controls.
The MTrPs point prevalence estimates in this review should be viewed with caution because future studies with large samples and high methodologic quality are likely to change them substantially.