Chiropractic and Spinal Manipulation: A Review of Research Trends, Evidence Gaps, and Guideline Recommendations

Abstract

Chiropractors diagnose and manage musculoskeletal disorders, commonly using spinal manipulative therapy (SMT). Over the past half-century, the chiropractic profession has seen increased utilization in the United States following Medicare authorization for payment of chiropractic SMT in 1972. We reviewed chiropractic research trends since that year and recent clinical practice guideline (CPG) recommendations regarding SMT. We searched Scopus for articles associated with chiropractic (spanning 1972-2024), analyzing publication trends and keywords, and searched PubMed, Scopus, and Web of Science for CPGs addressing SMT use (spanning 2013-2024). We identified 6286 articles on chiropractic. The rate of publication trended upward. Keywords initially related to historical evolution, scope of practice, medicolegal, and regulatory aspects evolved to include randomized controlled trials and systematic reviews. We identified 33 CPGs, providing a total of 59 SMT-related recommendations. The recommendations primarily targeted low back pain (n = 21) and neck pain (n = 14); of these, 90% favored SMT for low back pain while 100% favored SMT for neck pain. Recent CPG recommendations favored SMT for tension-type and cervicogenic headaches. There has been substantial growth in the number and quality of chiropractic research articles over the past 50 years, resulting in multiple CPG recommendations favoring SMT. These findings reinforce the utility of SMT for spine-related disorders.

Keywords: bibliometrics; chiropractic; clinical practice guidelines; low back pain; review; spinal manipulation.

Figure 1

Publication trends of chiropractic research from 1970 to 2023. Image (A) (publications per year; blue) and Image (B) (cumulative publications; orange). The most recent year (2024) is not shown to provide a more accurate representation of publication trends and account for lags in indexing.

Figure 2

Trends in topic keywords per year from 1972 to 2024. The plot displays keywords having a frequency of ≥150 and words per year of 1, thereby tending to omit keywords from 1972 to 1981 given the relative lack of research during that time. The bars represent the first and third quartiles of keyword representation, while the circle position represents the median year of occurrence. The size of the circle corresponds to the total frequency of the keyword occurrence. We used a thesaurus to merge synonymous terms, and we removed meaningless terms (e.g., “article” and “research”) given the threshold for occurrence. The figure was created by Robert Trager using Bibliometrix and Biblioshiny.

Figure 3

Keyword co-occurrence map (1972–2024). The figure was created using author keywords using Scopus, with the parameters of occurrences (~35), ignoring the term “chiropractic”, scale of 2.0, strength ≥ 8, using a thesaurus to merge similar terms. The size of the circles increases with greater occurrence of keyword use, while bars connecting circles indicate co-occurring keywords, with the width of bars indicating the strength of co-occurrence. The figure was created by Robert Trager using VOSviewer, version 1.6.20.

Figure 4

Article selection diagram. Abbreviations: Cumulative Index to Nursing and Allied Health Literature (CINAHL), spinal manipulative therapy (SMT). Please note that a large number of studies were excluded at the title/abstract phase due to our broad search strategy. Many articles mentioned clinical practice guidelines but did not constitute guidelines themselves (e.g., protocols, randomized trials, guideline adherence studies). Full-text exclusions with specific reasons are detailed in Supplemental File S2.

Figure 5

Timeline plot of clinical practice guideline recommendations for spinal manipulation by condition and year from 2014 to 2024. Recommendations for episodic and chronic tension-type headaches were grouped under “Any” to simplify the plot, considering these terms typically denote headache frequency rather than duration. Abbreviations: lower back pain (LBP), lumbar radiculopathy (LR), pelvic girdle pain (PGP), vasomotor symptoms (VMS). Recommendations in favor (“Yes” or “Multimodal”) are shown in light and dark green, respectively, while recommendations not in favor (“No” or “Insufficient evidence”) are shown in red and orange, respectively.