The mechanisms of MT in the treatment of MSK pain: A comprehensive model
(Bialosky, Bishop, Price, Robinson, & George, 2009)
Aims: Present a comprehensive model of potential individual mechanisms of MT that the current literature suggests as pertinent and the potential interaction between these individual mechanisms.
Methods: Expert Literature review.
Results: The literature suggests:
Biomechanical effect of MT; however, lasting structural changes have not been identified, clinicians are unable to reliably identify areas requiring MT, the forces associated with MT are not specific to a given location and vary between clinicians, choice of technique does not seem to affect outcomes, and sign and symptom responses occur in areas separate from the region of application. The effectiveness of MT despite the inconsistencies associated with a purported biomechanical mechanism suggests that additional mechanisms may be pertinent.
-Peripheral mechanisms: Studies suggest a potential mechanism of action of MT on MSK pain potentially mediated by the peripheral nervous system through cytokines, b-endorphin, anandamide, N-palmitoy- lethanolamide, serotonin, endogenous cannabinoids and substance P levels.
-Spinal mechanisms: MT may exert an effect on the spinal cord. MT may decrease activation of the dorsal horn of the spinal cord (shown in rats). MT is associated with hypoalgesia, afferent discharge, motoneuron pool activity, and changes in muscle activity all of which may indirectly implicate a spinal cord mediated effect.
-Supraspinal mechanisms: Literature suggests the influence of specific supraspinal structures such as the anterior cingular cortex (ACC), amygdala, periaqueductal gray (PAG), and rostral ventromedial medulla (RVM) in response to pain. A trend was noted towards decreased activation of the supraspinal regions responsible for central pain processing. The model accounts for direct measures of supraspinal activity along with associated responses such as autonomic responses and opiod responses to indirectly imply a supraspinal mechanism.
Biases: Expert’s review = low level of evidence.
In practice: This model suggests a mechanical stimulus initiates a number of potential neurophysiological effects which produce the clinical outcomes associated with MT in the treatment of musculoskeletal pain.
Bialosky, J. E., Bishop, M. D., Price, D. D., Robinson, M. E., & George, S. Z. (2009). The mechanisms of manual therapy in the treatment of musculoskeletal pain: A comprehensive model. Manual Therapy, 14(5), 531–538. https://doi.org/10.1016/j.math.2008.09.001