A randomized controlled trial recently published in the Journal Manipulative and Physiological Therapeutics has taken on the task of comparing two different cervical manipulation techniques for mechanical neck pain . While HVLA (high-velocity, low-amplitude) cervical manipulation has previously been shown to be effective for neck pain, the jury has still been out as to which technique was most effective for the condition. The study emerged from Australia’s own Macquarie University. Here’s how it went down.
Mechanical neck pain is said to be the most common type of neck pain, and is the reason for many a chiropractic visit. Mechanical neck pain (or MNP) occurs “when movement or sustained postures strain the neck causing pain in the discs, tendons, muscles and/or joints of the spine .” It is “nonspecific pain of non-pathological origin occurring in the cervical spine” and is almost as common as low back pain, with annual prevalence of the condition ranging from 30-50% .
There are two common approaches to cervical manipulation used for this condition. One is Manually Applied Manipulation or MAM, and the other is Instrument Applied Manipulation or IAM. Up until the release of this study, there had been no clear evidence to preference one over the other .
This study, while supporting the findings of recent studies comparing MAM, IAM and usual care cohorts with low back pain, contradicted a number of smaller studies that had indicated the approaches yielded similar results for MNP [4-6].
It involved 73 participants who were aged between 18 and 35 years and who had a history of mechanical neck pain of greater than one month. They were screened for contraindications to cervical manipulation and were then split into one control and two intervention groups. The first of the groups was the control group who received “a standardized active muscle stretching routine. The second group received the same muscle stretching routine followed by a single manually applied manipulation. The third and final group received the muscle stretching routine and a single instrument applied manipulation.
It should be noted that the manual manipulation group was adjusted by a single practitioner with 30 years experience, and the instrument-applied manipulation group was adjusted by a different practitioner with 29 years experience. “The choice of which level of the cervical spine to address was at the discretion of the clinician following static palpation” and all MAM’s were administered using lateral flexion thrust manipulation . For the IAM’s, the Activator IV instrument was used and set to “2” with the manipulative force delivered to the pedicle-lamina junction of the involved segment. No Activator Methods protocols were used.
The significant difference between manual and instrument applied manipulation for neck pain lies in how they approach the physiological range of motion. That is, MAM involves “the application of force aimed at moving a joint beyond its physiological range of motion (ROM) without exceeding the anatomical limit.” IAM is thought to achieve an effect without doing so.
For the sake of the trial, the following measurements were recorded:
- Subjective pain levels
- Pressure pain threshold
- Cervical range of motion
- Hand grip strength
- Wrist blood pressure
- Adverse events.
The study indicated that, while both methods were effective, they were not identical in their results. In fact, the approaches yielded different results across the five key areas listed above. The authors stated :
“The findings reported in this study show that a single application of cervical manipulation increases cervical ROM and decreases subjective pain levels in people with MNP. The study also shows that cervical manipulation produces remote effects. However, these effects are noticeably different for each type of manipulation. MAM produced immediate increases in rotation bilaterally and lateral flexion on the contralateral side to manipulation compared with IAM and a decrease in subjective pain levels 7 days postintervention when compared with control. IAM did not produce equivalent changes.”
Although the article itself goes into far more detail, some of the differences between the two approaches are as follows:
- For subjective pain levels, MAM appeared to be more effective than mobilization in reducing pain. Time appeared to be a factor, with improvements noted at 2, 4 and 7 days postintervention. This contradicted previous studies, a fact potential explained by study design differences.
- For cervical range of motion, the MAM group reported immediate increased in cervical rotation and lateral flexion. Again, this was unique to this study, potentially the result of an MAM technique which facilitated “distraction and displacement of the of the cervical spine .”
- Hand grip-strength was another area that contradicted the results of previous studies. Authors remarked that theirs was “the first study to report immediate increases in hand grip-strength following IAM.” Other studies had reported this affect bilaterally and ipsilaterally after cervical MAM.
- The matter of adverse events was an interesting one. The study yielded 6 mild adverse events, but four of these were in the control group. The MAM and IAM group yielded one each. They included stiffness, mild soreness and pain during neck movement. Interestingly, the IAM group noted two interesting reactions that did not fit the adverse events definition. The participants reported “feeling unbalanced due to manipulation of only one side of the neck” and “increased clicking in the cervical spine following manipulation.”
This study gives us a strong indication that not all techniques return the same results. The authors of the study remarked that the results were “consistent with the hypothesis that the biomechanical characteristics of different spinal manipulation techniques may be responsible for varying clinical effects,” before noting that this was not yet definitive and that further research investigating the nature of the changes was warranted.
As research advances, we are gaining further insight into the mechanisms of chiropractic. This piece of research is a wonderful addition to that body of work, and another randomized controlled trial to add to the library. For full and detailed results of the study, check out the complete report (referenced below).
 Gorrell L, Beath K, Engel R (2016), “Manual and Instrument Applied Cervical Manipulation for Mechanical Neck Pain: A Randomized Controlled Trial,” Journal Manipulative and Physiological Therapeutics, June 2016, pp. 319-329, doi: http://dx.doi.org/10.1016/j.jmpt.2016.03.003
 Staff Writer (2015), “Neck Pain,” Australian Pain Management Association, https://www.painmanagement.org.au/2014-09-11-13-34-03/2014-09-11-13-35-16/273-what-is-causing-my-neck-pain.html retrieved 6 September 2017
 Bryans R, Decina P, Descarreaux M, Duranleau M, Marcoux H, Potter B, Reugg R, Shaw L, Watkin R and White E (2013), “Evidence-Based Guidelines for the Chiropractic Treatment of Adults with Neck Pain,” Journal Manipulative and Physiological Therapeutics, Vol. 37, No. 1, DOI: https://doi.org/10.1016/j.jmpt.2013.08.010
 TG Wood, CJ Colloca, R Matthews (2001), “A pilot randomized clinical trial on the relative effect of instrumental (MFMA) versus manual (HVLA) manipulation in the treatment of cervical spine dysfunction,” Journal Manipulative and Physiological Therapeutics,, 24 (2001), pp. 260-271
 D Yurkiw, S Mior (1996), “Comparison of two chiropractic techniques on pain and lateral flexion in neck pain patients: a pilot study,” Journal Chiropr Tech, Vol. 8 (1996), pp. 155-162
 M Schneider, M Haas, R Glick, J Stevans, D Landsittel (2015), “Comparison of spinal manipulation methods and usual medical care for acute and subacute low back pain: a randomized clinical trial,” Journal Spine, Vol 40 (2015), pp. 209-217