How does orthopaedic manual physical therapy work? The available evidence strongly suggests that it is by a neurophysiologic affect. (1) The differences of effect between mobilization and manipulation techniques have not been consistent, or clear. The specific neurophysiologic mechanism and where it is occurring is also not well understood.

Fisher (2016) The effect of velocity of joint mobilization on corticospinal excitability in individuals with history of ankle sprain in the most recent JOSPT may be an interesting step towards better understanding the neurophysiologic effects of OMPT. The researchers, led by Beth Fisher, included AAOMPT founding fellow Kornelia Kulig.

The population studied was individuals with recurrent ankle sprains. Examined were the pre and post talocrural intervention measures of mobility, functional balance, and neurophysiologic change between three groups. Those groups were a 30 second traction mobilization, a gapping manipulation, and a control group.

Disappointingly, mobility and function remained unchanged across the groups. The study proposed several possibilities to explain this result, BUT that wasn’t the interesting part.

Previous research involving stretching, manipulation, or mobilization has shown the neurophysiologic change of a short term decrease in the H-reflex response (that’s the Hoffman’s reflex, not to be confused with the Hoffman’s sign). The Hoffman’s reflex is measured by EMG and demonstrates a neurophysiologic change at the level of the spinal cord. In this study surface EMGs were combined with transcranial magnetic stimulation (TMS). Never heard of it? Well I had to look this one up too!   It is a fairly new technique used for a growing number of diagnostic and treatment purposes. In this case it was to measure activity between the motor cortex and select targets muscles. These neurophysiologic measurements were made both at rest and during sub-maximal activity.

The manipulation group showed a significant increase in corticospinal activity, not shown in the other groups. In the 30 second traction mobilization group, corticospinal activity was decreased, which is consistent with H Reflex observations of OMPT. Perhaps this is reflective of different joint receptors being triggered with sustained traction vs manipulation as Wyke’s (2, 3) articular neurology work would suggest. The maximal evoked potential of one of the muscles studied (tibialis anterior) was also increased specifically in the manipulation group. Other muscles curiously were unaffected.

The facilitation of activity in the cortico-spinal motor tracts shown with the manipulation group is similar to activity observed during learning new motor tasks( 4, 5). This study is suggesting that manipulation may specifically potentiate motor learning, within the brain.

Consistent with other studies, these neurophysiologic effects are of limited duration to about 30 minutes.  Previous studies (6-10) support that OMPT alone does not demonstrate significant improvements. For that to occur, exercise or muscular re-education is an essential component. Remember that after any OMPT intervention, motor learning is the key to making a real and durable difference. If they leave the clinic before motor learning is initiated, then there goes your window to seal the deal with post-OMPT optimized motor learning. It appears that with OMPT, and perhaps manipulation specifically, the entire nervous system may be set up to learn something new. When you use manipulation, remember to act on your opportunity and re-educate!

– W Bryant Miller, PT, DSc, OCS, COMT, FAAOMPT

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References

1. Bialosky JE, Bishop MD, Price DD, Robinson ME, George SZ. The mechanisms of manual therapy in the treatment of musculoskeletal pain: a comprehensive model. Man Ther. 2009;14(5):531-8.
2. Freeman MA, Wyke B. The innervation of the knee joint. An anatomical and histological study in the cat. J Anat. 1967;101(Pt 3):505-32.
3. Wyke B. The neurology of joints. Ann R Coll Surg Engl. 1967;41(1):25-50.
4. Rittig-Rasmussen B, Kasch H, Fuglsang-Frederiksen A, Jensen TS, Svensson P. Specific neck training induces sustained corticomotor hyperexcitability as assessed by motor evoked potentials. Spine (Phila Pa 1976). 2013;38(16):E979-84.
5. Jensen JL, Marstrand PC, Nielsen JB. Motor skill training and strength training are associated with different plastic changes in the central nervous system. J Appl Physiol (1985). 2005;99(4):1558-68.
6. Bang MD, Deyle GD. Comparison of supervised exercise with and without manual physical therapy for patients with shoulder impingement syndrome. J Orthop Sports Phys Ther. 2000;30(3):126-37.
7. Deyle GD, Henderson NE, Matekel RL, Ryder MG, Garber MB, Allison SC. Effectiveness of manual physical therapy and exercise in osteoarthritis of the knee. A randomized, controlled trial. Ann Intern Med. 2000;132(3):173-81.
8. Fiechtner JJ, Brodeur RR. Manual and manipulation techniques for rheumatic disease. Med Clin North Am. 2002;86(1):91-103.
9. Hurwitz EL, Carragee EJ, van der Velde G, Carroll LJ, Nordin M, Guzman J, et al. Treatment of neck pain: noninvasive interventions: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. Spine. 2008;33(4 Suppl):S123-52.
10. Ottawa. Ottawa panel evidence-based clinical practice guidelines for therapeutic exercises and manual therapy in the management of osteoarthritis. Phys Ther. 2005;85(9):907-71.