Incomplete reporting of manual therapy interventions and a lack of clinician and setting diversity in clinical trials for neck pain limits replication and real-world translation. A scoping review

ABSTRACT

Introduction

Neck pain is a leading cause of disability, and manual therapy (MT) is a common intervention used across disciplines and settings to treat it. While there is consistent support for MT in managing neck pain, questions remain about the feasibility of incorporating MT from research into clinical practice. The purpose of this scoping review was to assess the adequacy of MT intervention descriptions and the variability in clinician and setting for MT delivery in trials for neck pain.

Methods

Medline (via PubMed), CINAHL, PEDRo, and the Cochrane Central Registry for Controlled Trials were searched for clinical trials published from January 2010 to November 2021. A 11-item tool modified from the Consensus on Exercise Reporting Template was used to assess appropriateness of intervention reporting. Clinicians, subclassifications of neck pain, and clinical settings were also extracted.

Results

113 trials were included. A low percentage of studies provided the recommended level of detail in the description of how MT was delivered (4.4%), while 39.0% included no description at all. Just over half of trials included clinician’s qualifications (58.4%), dose of MT (59.3%), and occurrence of adverse events (55.8%). The proportion of trials with clinicians delivering MT were physical therapists (77.9%), chiropractors (10.6%), and osteopaths (2.7%).

Discussion/Conclusion

These results reveal incomplete reporting of essential treatment parameters, and a lack of clinician diversity. To foster reproducibility, researchers should report detailed descriptions of MT interventions. Future research should incorporate a variety of MT practitioners to improve generalizability.

Introduction

Manual therapy (MT) is a common intervention used to treat all subclassifications of neck pain and related headache and extremity pain [1–3]. It is characterized as a set of skilled hand movements intended to improve tissue extensibility, increase range of motion, mobilize and manipulate joints and related soft tissue, and modulate pain [4]. MT is recommended in the treatment of neck pain by clinical practice guidelines, and has been demonstrated to be effective in several clinical trials [5–8]. The ability to implement evidence-based interventions is critical to research translation efforts. A key to implementation is the ability to replicate the intervention in real-world settings as it was delivered in the trial. This is also important because the label of ‘manual therapy’ is broad and can encompass a range of various interventions with high levels of heterogeneity. The ability to replicate any intervention, especially one as diverse as MT, is dependent on how well treatment parameters are described when reported in published clinical trials.

Part of understanding the intervention is being familiar with the background and training of the clinician delivering the treatment in each trial. MT delivery between and even within disciplines can be highly variable, and the lack of consistency can also be quite high. MT is currently practiced by a wide variety of healthcare practitioners, including osteopathic physicians, medical doctors, physical therapists, and chiropractors [9]. It is unknown, however, how researchers in each discipline have contributed to the body of evidence supporting the use of MT for neck pain.

While replicability of MT in neck pain trials has been previously investigated [10], only nonspecific neck pain trials were assessed and a more generic intervention assessment reporting tool was used. This may not provide the level of detail necessary to facilitate replication of MT interventions, and its effectiveness has been evaluated for several other important neck-related conditions (e.g., whiplash, radiculopathy, cervicogenic headache) [11–15]. In addition, there has been limited formal assessment of clinician type and clinical background for those delivering the MT in these neck pain trials. Therefore, the purpose of this review was to assess the replicability of MT interventions used in trials that investigated all types of mechanical neck pain using a MT specific checklist, and to conduct a comprehensive assessment of the types of clinicians and settings in MT trials for neck pain.

Methods

This was a scoping review of the literature. The Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist was used to guide reporting [16].

In order to capture current clinical trial design and to reflect modern clinical guidelines’ recommendations of MT for neck pain, a search for studies published between 1 January 2010 to 30 November 2021 was performed. For the purposes of this study, MT was defined as any procedure that included thrust and/ or non-thrust joint manipulation/mobilization. Randomized, controlled trials and non-randomized trials published in English-language, peer-reviewed journals were included in this search. All neck pain phenotypes were included (e.g., nonspecific pain, radiculopathy, whiplash associated disorders). Studies were excluded if the outcome of interest was not a measure of pain intensity or function/disability.

Studies were retrieved using four different databases: Medline (via PubMed), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Physiotherapy Evidence Database (PEDRo), and the Cochrane Central Registry for Controlled Trials (CENTRAL). Our search strategy included Medical Subject Headings (MeSH) terms or CINAHL headings combined with the Boolean operators ‘AND’ and ‘OR’ to ensure a complete investigation of the topic. Specific terms were chosen based on common terminology used by various practitioners of MT. Since there are both inter- and intraprofessional inconsistencies in MT nomenclature, the use of the chosen MeSH and CINAHL headings provide the most comprehensive search across disciplines [17]. Additionally, to ensure that the inclusion criteria of MT for neck pain was fully represented, the MeSH terms for neck pain and diagnoses associated with neck pain were included. Where available in the selected databases, filters for peer reviewed, clinical trials, published in the last 12 years, human trials, and published in English were included in the search strategy. These were added to narrow the search through exclusion criteria. An example search strategy is provided in the Appendix A.

Study selection consisted of identifying those primary resources that met the inclusion criteria. Identification of clinical trials investigating MT for neck pain, irrespective of the specific technique or location of delivery and outcomes of the intervention, was performed by two independent reviewers (JL and WO). Initial screening of studies was based on information collected from the titles and abstracts. When there was a disagreement between investigators, there was a second review of the study. A third reviewer (JY) was available to address any unresolved disputes if necessary. Once the initial screening was complete, a second, full-text screen occurred by the same reviewers following the same process as the title and abstract screening.

Reproducibility of manual therapy

The most common checklist tool used to guide thoroughness of reporting interventions in trials is the Template for Intervention Description and Replication (TIDieR). It was developed generically for trial interventions in general as an extension of item 5 in the CONSORT statement [18,19]. Because it lacked the nuance to capture important exercise therapy intervention parameters, the 16-item Consensus on Exercise Reporting Template (CERT) template was developed to meet this need [20]. It was designed to ensure that the important aspects of exercise therapy are provided to improve the reproducibility of the exercise intervention in clinical practice [20]. No such checklist currently exists specifically for MT interventions. Therefore, we used a modified version of the CERT. The original CERT checklist is specific to exercise interventions, including type of exercise equipment or individual versus group exercise; however, there are also characteristics that are relevant to MT, such as a detailed description of the exercise for replication and adverse events [20]. While these important items are found on the CERT, they are not as clearly defined on the TIDieR checklist, further supporting the need for more definitive reporting criteria for specific interventions like MT. In the modification of the CERT, we removed criteria that were irrelevant to MT, added components and specifics that were lacking, combined items when appropriate, and constructed wording that was tailored to MT intervention descriptions. To assess how well MT interventions were described for replicability, standardized terminology recommended by the Task Force on Standardizing Manual Therapy Terminology was used [9,17]. A study’s MT intervention selection was considered pragmatic if the treating clinician had the freedom to determine the technique parameters, [21] compared to a prescriptive MT approach where technique selection and parameters were predetermined by the study protocol. See Table 1 for the modification of the CERT to facilitate evaluation of reporting consistency of MT interventions.

Table 1.

Modification of the CERT to facilitate evaluation of reporting consistency of MT interventions.

CERT Criteria	Modified CERT Criteria for MT	Definition
Item 1 – Detailed description of the type of exercise equipment*
Item 2 – Detailed description of the qualifications, expertise and/or training	Detailed description of the qualifications, expertise, or training of the practitioner	The experience of the clinician applying the MT in the clinical trial beyond their professional identity (e.g., special training in MT, years practicing MT, additional credentials in MT)
Item 3 – Describe whether exercises are performed individually or in a group*
Item 4 – Describe whether exercises are supervised or unsupervised; how they are delivered*
Item 5 – Detailed description of how adherence to exercise is measured and reported*
Item 6 – Detailed description of motivation strategies*
Item 7a – Detailed description of the decision rule(s) for determining exercise progression
Item 7b – Detailed description of how the exercise program was progressed
Item 8 – Detailed description of each exercise to enable replication	Detailed description of the application of MT	Includes the following a) rate of force b) location in the range of available motion c) direction of force d) target of force e) relative structural movement f) patient positiona
Item 9 – Detailed description of any home program component	Detailed description of any home program that was provided	Includes if a home program was provided to the patient or addresses it was not included
Item 10 – Describe whether there are any non-exercise components	Description of any adjunct interventions	Includes if interventions were provided in addition to the MT or addresses that none were included
Item 10 – Describe whether there are any non-exercise components	Description of the patient education provided to the patient regarding MT	Includes if patient education was provided or addresses none was included
Item 11- Describe the type and number of adverse events that occur during exercise	Description of the type, severity, and number of adverse events	Reports adverse events from the delivery of MT or addresses that no adverse events occurred
Item 12 -Describe the setting in which the exercises are performed	Description of the setting where MT was delivered
Item 13 – Detailed description of the exercise intervention	Detailed description of the dosage of MT that was applied	Includes a full description of the dosage including the number of times or duration and grade that MT was applied
Item 14a – Describe whether the exercises are generic (one size fits all) or tailored	Description of the decision-making process for delivering MT	Includes a description of the decision-making as either; pragmatic – the clinician determined how they wanted to deliver the MT intervention; or prescriptive – location, technique, and/or dosage was predetermined and dictated to the clinician
Item 14b – Detailed description of how exercises are tailored to the individual Item 15 – Describe the decision rule for determining the starting level	Detailed description of how MT was tailored for the individual patient in pragmatic delivery	Includes a description of the decision-making process for the starting point, type, grade, and target
	Description of how screening for the appropriateness of MT was conducted♱	Includes a description of the decision-making process of how the patient was considered appropriate for MT considering contraindications and precautions reported directly as a part of the examination for intervention delivery or in the inclusion/exclusion criteria
16a – Describe how adherence or fidelity is assessed/measured* 16b – Describe the extent to which the intervention was delivered as planned*
* Item not included in modified CERT	♱Item not included in the CERT	aDescribed by the Task Force on Standardizing Manual Therapy Terminology [9,17]

Data extraction

Covidence was used to organize the extracted elements from each trial [22,23], performed by each independent reviewer. This was then combined into a final working data set, and any disagreements were discussed to achieve consensus. Items extracted from relevant clinical trials included elements of the modified CERT seen in Table 1. In addition to this checklist, we collected information on the discipline delivering MT (physical therapist, chiropractor, medical doctor, osteopathic physician, or naprapath), the type of neck pain (nonspecific, cervicogenic headache, whiplash, radiculopathy), country and setting where the study was performed, whether the reporting of adverse events was addressed (yes/no), and whether screening for appropriateness MT was addressed in the inclusion/exclusion or the methods.

Data were synthesized through frequency counts of reporting items present in trials. Then an overall assessment of the generalizability of the research evidence could be made. Additionally, the descriptive statistics, including frequency distributions and proportions of clinician-type and clinical setting, was assessed. This allowed for determining the prevalence of the treating clinicians in MT clinical trials for neck pain, a secondary outcome of this review.

Results

A search of the databases resulted in 795 studies after all duplicates were removed. Once title and abstract screening was complete, there were 118 studies that met the criteria for full-text review. After full-text review, there were 113 studies that met full inclusion criteria. Figure 1 demonstrates the PRISMA flowchart of the study selection process.

Figure 1.

PRISMA flow diagram of search strategy and results.

Results showed that a low percentage of studies provided a sufficiently detailed description of how MT was delivered (4.4%) per the criteria established by the Task Force on Standardizing Manual Therapy Terminology in 2008 [9,17], with 39.0% of all trials providing no description of the MT that was applied. There were also a limited number of trials that described the patient education (30.1%) or associated home exercise program (43.4%). The most consistent item reported was how the delivery of MT was approached, either pragmatic or prescriptive (91.2%). For the complete results of this assessment see Table 2.

Table 2.

Modified CERT.

Items	Number of Items Present N (% of all MT trials)
Were clinician qualifications provided?	66 (58.4)
Was the method of screening for contraindications to MT provided?	106 (93.8)
Described method beyond exclusion criteria	40 (35.4)
Was the decision of how the delivery of MT was decided, pragmatic or prescriptive, provided?	103 (91.2)
Was the decision of how to tailor MT (if pragmatic) provided?	65 (73.0)♱
Was a full description of the MT provided?*	5 (4.4)
Partial description	64 (56.6)
Was the dosage of MT delivered provided?	67 (59.3)
Was there a description of the type or number of adverse events provided?	63 (55.8)
Was there a description of the adjunct interventions provided or addressed if there were none?	84 (74.3)
Was there a description of the education used provided or addressed if there was none?	34 (30.1)
Was there a description of the home exercise program provided or addressed if there was none?	49 (43.4)
Was there a description of the setting where MT was provided?	81 (71.7)
*Description per Task Force on Standardizing Manual Therapy Terminology [9,17]	(%N) Percent of total sample (N = 113) ♱Percent within trials that reported pragmatic MT delivery (n = 89)

Clinician specialty delivering the MT and clinical setting was also evaluated. The most common clinicians delivering care were physical therapists (77.9% of trials) followed by chiropractors (10.6%), osteopaths (2.7%), naprapaths (1.8%) and medical doctors (0.9%). In a small number of studies (0.9%), clinicians from multiple backgrounds (physical therapists, chiropractors, and osteopaths) delivered the MT, and in 5.3% of the trials, the practitioner was not clearly specified. Of the 113 trials reviewed, nonspecific neck pain (68.1%) was the most frequent diagnostic label investigated, followed by cervicogenic headache (13.3%), cervical radiculopathy (12.4%), whiplash associated disorder (0.9%), and 5.3% of trials allowed for all types of neck pain through their inclusion/exclusion criteria. For the clinical setting where MT was delivered, the university setting (26.5%) was found to be the most prevalent, then private practice (22.1%), hospitals (18.6%), and research labs (4.4%). Out of the 113 studies explored, 28.3% did not clearly specify the setting where MT was applied. The identification of what country each study was conducted in revealed that the majority of trials were performed in the United States (17.7%), Spain (16.8%), India (11.5%), and Pakistan (6.2%). The characteristics of the 113 studies are included in Table 3.

Table 3.

Summary of settings, clinicians, and neck pain phenotypes represented in MT trials.

Characteristic	113 Total Trials N (% of all MT Trials)
Country of origin
United States	20 (17.7)
Spain	19 (16.8)
India	13 (11.5)
Not specified	9 (8.0)
Pakistan	7 (6.2)
Turkey	5 (4.4)
Australia	4 (3.5)
Egypt	4 (3.5)
Korea	4 (3.5)
Canada	3 (2.7)
Netherlands	3 (2.7)
Sweden	3 (2.7)
Thailand	3 (2.7)
Hong Kong	2 (1.8)
Brazil	2 (1.8)
Germany	2 (1.8)
Iran	2 (1.8)
Nigeria	2 (1.8)
Norway	1 (0.9)
Poland	1 (0.9)
Portugal	1 (0.9)
Saudi Arabia	1 (0.9)
South Africa	1 (0.9)
New Zealand	1 (0.9)
Neck pain type
Nonspecific	77 (68.1)
Cervicogenic headache	15 (13.3)
Radiculopathy	14 (12.4)
All types	6 (5.3)
Whiplash	1 (0.9)
Study/clinical setting
Not specified	32 (28.3)
University	30 (26.5)
Private	25 (22.1)
Hospital	21 (18.6)
Research laboratory	5 (4.4)
Clinician
Physical Therapist	88 (77.9)
Chiropractor	12 (10.6)
Not specified	6 (5.3)
Osteopath	3 (2.7)
Naprapath	2 (1.8)
Medical Doctor	1 (0.9)
Physical Therapist, Osteopath, and Chiropractor	1 (0.9)

Discussion

Research is necessary to improve the quality of care for patients. However, it is only as good as its ability to make real-world impact in clinical practice. When generalizability is poor or unknown and interventions cannot be replicated, the impact of research becomes more questionable. The current recommendations from clinical practice guidelines across individual disciplines include the use of MT for the treatment of neck pain [5,8,24–26]. These recommendations have remained consistent over the last few decades and across guidelines compared to other interventions [27]. They are also applicable across subclassifications of neck pain with varying degrees of severity, irritability, and stage of condition [8]. Despite the consistency in recommendations, there is a lack of clarity regarding the delivery and dose of MT among studies. This is relevant as effect sizes vary across trials and can be influenced by the dose of the intervention. A better understanding of how manual therapy is delivered in trials is necessary for reproducing similar results. Therefore, the purpose of this review was to assess the replicability of MT interventions used in trials for mechanical neck pain using a MT-specific checklist, and to conduct a comprehensive assessment of the types of clinicians that are delivering the MT interventions in these trials.

These results indicate that the reporting of intervention details in MT trials, to include standardization of MT terminology, is poor. Other factors can also influence reproducibility. A substantial number (77.9%) of MT trials for neck pain over the last 12 years used physical therapists to deliver the intervention. Over a quarter (26.5%) of studies were performed in an academic setting, and 17.7% of all studies were performed in the United States. With variation in how MT is taught and performed across disciplines and throughout the world, these results highlight some of the challenges of translating evidence from the clinical sciences to real-world implementation.

While we did find that the majority of trials reported the clinicians’ qualifications (58.4%), dose of MT (59.3%), how the intervention was tailored (73.0%), setting (71.7%), and addressed adjunctive interventions (74.3%), there is still room for improved reporting of these items in many trials.

Consistency in reporting

The lack of reporting consistency in MT trials for neck pain is concerning but not surprising. Similar challenges to implementation in real-world settings have been identified with exercise interventions [28–32]. In this review, it was found that a minority of studies fully described the MT provided (4.4%), the method of screening for the appropriateness of MT beyond reporting the exclusion criteria (35.4%), number and types of adverse events (55.8%), and whether a home exercise program (43.4%) and/or patient education (30.1%) were provided to patients. These components of MT research are instrumental in allowing clinicians to apply the findings to their own clinical practice and ensure patient safety.

Only 4.4% of included studies provided a full, detailed description of the technique(s) based on proposed standard terminology for MT [9,17]. A common language to describe these interventions is necessary to improve reproducibility. Due to the substantial number of MT techniques, different body regions, all with varying speeds, amplitudes and body positions, replication is very challenging. The studies in this review were all published after the proposed terminology from the Task Force on Standardizing Manual Therapy Terminology was available. Over a third (39.0%) of all trials provided no description at all of their MT intervention.

How patients were screened for appropriateness in these trials helps readers better understand how patient selection may be applicable in their settings. During the screening of patients for appropriateness for cervical manipulation, Rushton et al. recommends a comprehensive examination over a single vertebral artery special test to determine safety of treatment [33]. For patients who have experienced trauma such as after whiplash associated disorder, the Canadian C-Spine rules are an important consideration to determine whether there is a need for a cervical spine radiograph before treatment [34]. In the examination of patients with comorbidities or findings suggestive of upper cervical instability, a thorough neurovascular exam and ligamentous testing can help determine risk versus benefit of MT [33,35]. While the majority of studies (93.8%) had exclusion criteria that represented contraindications to MT, these conditions were inconsistent across studies and did not fully provide clinicians with the examination skills necessary to safely replicate. Based on the limited number of studies in this review that explicitly described how participants were screened (35.4%), it is crucial that researchers prioritize the inclusion of this information in future trial reports to promote a better understanding of patient safety during MT interventions.

Although adverse events are rare, the biggest concern comes with MT directed at the cervical spine. With just over half of studies reporting the tracking of adverse events, a mandatory reporting item for clinical trials according to the CONSORT statement [18], there is need for improvement. This information allows the reader to assess risk versus reward in the application of those MT interventions, and is an important step in the clinical decision making process [33]. The application of MT to the cervical spine and adjacent structures can result in adverse events that range from mild soreness to severe neurovascular compromise [36]. As clinicians assess the literature, knowing what to monitor for and the prevalence of each type of adverse event can assist decision making and patient selection. Furthermore, taking into consideration risk factors for adverse events could guide the delivery of MT. Hurwitz et al. [36]. found that certain patient factors increased the likelihood of an adverse reaction to cervical thrust manipulation, and adverse reactions occurred less frequently after non-thrust manipulation in those who presented with these factors. Cleland et al. [7]. found that patients with neck pain, regardless of presentation, responded favorably to thoracic spine manipulation, thus allowing for MT delivery to those deemed not appropriate for manipulation directed at the cervical spine [7].

Providing information on adjunct interventions, like exercise therapy or patient education, is important. Education is foundational to any patient’s plan of care, considered an intervention, and can significantly impact outcomes [8]. For patients with acute whiplash associated disorder, advice to normalize activities is more beneficial than collar-use for the intermediate and long term [37]. Those with chronic neck pain with mobility deficits respond favorably to education and counseling that promotes an active lifestyle and adapts to the presence of cognitive and affective impairments [8]. There is moderate evidence that education encouraging return to work and exercise is beneficial for those diagnosed with chronic cervical radiculopathy [8]. Bialosky et al. found that educating and setting positive expectations about spinal manipulation can have an impact on outcomes [38]. This further highlights the importance of reporting education interventions that occur alongside MT interventions, as they have the potential to influence the effect sizes seen in MT trials. The limited number of trials that reported any details about patient education reinforces the need to ensure that education intervention details are included as part of standardized reporting criteria in future trials. Similar to education, when MT and exercise therapy are combined, outcomes are different than if MT is used in isolation for patients with neck pain with or without radiculopathy or cervicogenic headache [1,39]. For clinicians trying to reproduce MT clinical trials, knowing if exercise therapy was prescribed, and specifically which exercises were used, is critical for replicating results.

The reporting of clinician qualifications, the dosage applied, and adjunct interventions were more consistent with over half of the trials reporting these criteria, but there is still room for improvement. Knowing the experience level of the clinicians delivering MT in trials improves understanding of the generalizability of the results [40]. Details of the dose can assist in making clinical decisions about the use of the intervention in the clinic. Snodgrass et al. [41]. found that specific dosage parameters for MT for neck pain, including force of application, were necessary to achieve the desired outcome [41].

Clinician discipline and background

A spectrum of clinicians providing treatment was found in the literature [6,42–44]. On its face, this perceived diversity infers a balance across practitioners, but our results suggest otherwise. While the overall consensus for MT as an adjunctive treatment for neck pain is positive, there are often assumptions made that these outcomes can be extrapolated to any clinician whose scope of practice includes MT [8]. The performance of the techniques themselves can be similar across disciplines, but the clinical reasoning used to determine the when and why of its delivery can vary substantially across, or even within, clinician specialties [45].

The differences in decision making among clinician specialties underscores the need to delineate MT practitioners providing manipulative interventions. According to a 2019 analysis of Canadian chiropractic websites, 33% of chiropractors made claims regarding spinal subluxations [46]. Osteopaths assess and target treatment toward somatic dysfunctions, characterized by positional asymmetry, motion restriction, and soft tissue abnormalities and tenderness [47]. Osteopathic manipulation may be philosophically distinct with significant variability from other healthcare professions [48]. In contrast, physical therapists often focus more on the use of active motion and mobility assessments to determine the location and dose of MT [49]. With the greater emphasis on active movement and manual examination for joint mobility and pain and less emphasis on the constructs of subluxation and somatic dysfunction, there are differences in clinical decision-making between physical therapists and the chiropractic and osteopathic models that warrant consideration. Caution has been called for in drawing conclusions from research where MT was delivered by a different profession due to variability in reasoning and application [50].

In summary, it is important to point out that because the overarching umbrella of what falls under MT can be complex, proper descriptions and reporting of MT interventions can be challenging. As we have outlined, some MT interventions can be quite variable making it difficult to describe them consistently with a sufficient level of detail. It is also unclear what level of specificity in MT delivery actually influences outcomes [51,52]. However, the call for improved reporting is less about assessing effectiveness and more about improving reproducibility. Limitations with space in journals can limit the amount of detail in reporting these intervention parameters; however, the use of online repositories, supplementary appendices, or protocol publications are all very easy and simple solutions for dissemination of more detailed accounts of MT interventions, and their use should be encouraged.

Limitations

There are limitations to the review that warrant discussion. First, the CERT checklist was developed specifically for assessing the reporting quality of exercise interventions. Even when modified for use with MT interventions it may still be inferior to a reporting checklist more formally designed to address the reporting of MT interventions. However, it is likely more relevant and provides more specific and useful details than the TIDieR checklist. Further research efforts to develop such a tool should be considered. Second, MT is a broad label and some of the items assessed may not be relevant to every intervention that could be classified as ‘manual therapy.’ A more valid MT reporting checklist would likely also struggle to adequately capture the range of intervention parameters within this treatment label. Third, this review does not represent MT definitions for use with other musculoskeletal conditions or other body regions, which also merits further investigation.

Conclusion

Overall, reporting of essential treatment parameters that allow for replication of MT interventions used in clinical trials for neck pain is insufficient. Also, most trials do not report the details and occurrence of adverse events along with whether any concurrent patient education and/or home exercises were provided. Additonally, there is a lack of diversity among MT practitioners. This limits the reproducibility and generalizability of this current body of literature. To foster reproducibility, researchers should consistently include proper descriptions of these interventions when reporting their results and journals/reviewers should request these elements. Future research should incorporate a wider variety of MT practitioners and settings to improve generalizability.

Funding Statement

The author(s) reported there is no funding associated with the work featured in this article.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/10669817.2022.2113295