Spinal manipulation (SM) is a manual technique commonly used by chiropractors, osteopaths, physiotherapists, physicians or bone setters. The aim usually is to correct misalignments or subluxations of the spinal joints.1 However, subluxations have repeatedly been found to be an invalid concept.e.g.2;3 Therefore, the use of spinal manipulation as a means to adjust subluxations is of debatable biological plausibility. Despite its implausibility, SM is still widely used for a broad range of conditions.
Numerous clinical trials of SM have been published. Their data are often less than uniform. In such a situation, systematic reviews (SRs) might provide the most conclusive answer regarding the effectiveness of SM. In 2006, a SR of SRs pertaining to spinal manipulation was published.4 In this article, we were able to include 16 SRs published between 2000 and May 2005. Our conclusion was that “we have found no convincing evidence from systematic reviews to suggest that SM is a recommendable treatment option for any medical condition”.4 Since then, numerous new SRs have been published which necessitates an update of our original SR.
The aim of this update was to critically evaluate the data from SRs of SM as a treatment for any human condition.
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After removal of duplicates, the searches generated 59 articles. Thirteen articles were excluded (Figure 1). The reasons for exclusion were: based on previous systematic reviews (n=3), practise guideline (n=2), protocol only (n=1), no explicit exclusion and inclusion criteria (n=5), no conclusion regarding effectiveness (n=2). Forty-five SRs met the above inclusion criteria.5-49
Key data of these reviews are summarized in Table 1. These SRs related to the following conditions: low back pain (n=7), headache (n=6), neck pain (n=4), asthma (n=4), musculoskeletal conditions (n=3), any non-musculoskeletal conditions (n=2), fibromyalgia (n=2), infant colic (n=2), any medical problem (n=1), any paediatric conditions (n=1), carpal tunnel syndrome (n=1), cervicogenic dizziness (n=1), dysmenorrhoea (n=1), gastrointestinal problems (n=1), hypertension (n=1), idiopathic scoliosis (n=1), lateral epicondylitis (n=1), lower extremity conditions (n=1), pregnancy and related conditions (n=1), psychological outcome (n=1), shoulder pain (n=1), upper extremity conditions (n=1) and whiplash injury (n=1). There was some overlap between these categories.
The SRs included chiropractic or osteopathic manipulations as well as manual therapy or any type of SM. Twenty SRs included more than 10 primary studies;5;8;10;12;20-24;28;30-32;36;39;41;42 47 48;49 and 6 included a meta-analysis.5;20;22;40;41;48 The conclusions drawn from most SRs were frequently cautious or negative (Table 2). For instance, for low back pain three SRs arrived at positive conclusions,10;40;49one arrived at equivocal conclusions37 and three arrived at negative conclusions.5;12;20 For asthma three SRs arrived at negative conclusions7;15;25 and one arrived at equivocal conclusions.27 For headaches two reached positive conclusions 9;19 whereas three reached negative conclusions6;18;29
For infant colic both reviews arrived at negative conclusions.17;26 There is insufficient evidence to determine whether SM can be beneficial in upper extremity conditions 24;30;31 For lower extremity conditions, one review arrived at positive conclusions.8 Thus there was an undeniable degree of contradiction between these SRs.
In the last decade, dozens of systematic reviews have assessed the value of SM in a wide variety of clinical conditions. Our own SR is now out-dated,4 and the present article is an attempt to update it. Twenty nine SRs have been published8;15-19;21;23;24;27;28;30-32;34;36-49 since our previous assessment. 4Nine of those 29 SRs suggested that SM is effective8;19;23;36;39;40 48 47;49 and twenty failed to do so.15-18;21;24;27;28;30-32;34;37;38;41-46 Therefore, most of these SRs failed to produce convincing evidence to suggest that SM is of therapeutic value.
We have previously shown that the conclusions of SRs of SM for back pain appear to be influenced by authorship and methodological quality. Osteopaths or chiropractors tend to publish low methodological quality systematic reviews associated with positive conclusions (Table 3 and 4). Seven (38%) of the 18 SRs published either by chiropractors or osteopaths arrived at overtly positive conclusions8;9;23;36;39;40;49 and 11 (62%) arrived at negative or equivocal conclusions.7;10;21;25;27;30;31;37;38;42;46 Twenty four (88%) of the 27 SRs by independent research groups reached negative or equivocal conclusions.5-8;11-18;20-22;24-35;37;38;41-46 Only three (12%) arrived at positive conclusions.19;47;48
The present analysis has several limitations that should be considered when interpreting its conclusions. Even though a thorough search strategy was employed, there is no guarantee that all relevant articles were located. The validity of conducting a SR of SR has its limitations; all SRs are prone to publication bias within the primary research data which they include and therefore any such bias may have been inherited in our study. Thirteen of the SR were from our unit; this fact might have introduced bias in our evaluation.
In conclusion, the notion that SM is an effective treatment option for any condition is currently not based on the evidence from rigorous SRs.