Joint manipulation (often referred to as “chiropractic adjustment”) has been practiced for many years as a treatment technique for relieving joint pain and restriction.

Traditionally performed by chiropractors, this style of treatment is also incorporated by many osteopaths and manual physiotherapists.

But what is really happening when a joint “cracks”? Why does it feel good? And does it really help?

As a physiotherapist that practices spinal manipulation, I answer these questions often.
My intention here is to offer some straight-forward, easy-to-understand answers…hopefully with minimal medical jargon!

1. What exactly is manipulation and when does it help?

 A joint is essentially the interface at which one bone meets and moves with another. Many joints in the body are enclosed within a sheath called a joint capsule and supported by soft-tissues around it, such as ligaments and muscles.

Using a specific thrust to a joint, a specially trained health professional may “adjust” the joint to create more range, this is called a joint manipulation.

 Manipulation is most helpful when a joint has shifted out of place, such as when you sleep with your neck in an awkward position or fall and jar the joint, resulting in it being “stuck”. In these instances, manipulation may be the ideal treatment for the problem and quickly resolve the pain.

Joints can also become stiff due to lack of exercise, prolonged or poor postures, or simply through the natural processes of aging.  For these longer standing situations of restriction or chronic pain, current research does not support the use of manipulation in isolation.^2,3,7,9.

This is not to say that it may not be useful to include joint manipulation within a treatment plan, but that it should be combined with other treatment methods, especially specific exercise to address the strength of the muscles supporting and the mobility of the joint. This combination of therapies will avoid dependency on the health practitioner and need for ongoing treatments for the short-term effects that the manipulation may provide.

2. What makes the joint “pop”?

 For those of us who have experienced having a joint manipulated, we know that there is often an audible “pop” associated with the thrust technique at the joint being treated.

The primary theory is that this sound results from a process called “cavitation”.

Cavitation is the engineering phenomenon that describes the generation and collapse of gas or vapor bubbles in a liquid.¹  It is this popping of the small microscopic gas bubbles within the joint that causes the characteristic “popping” or “cracking” sound that you hear.

3. Why do I feel better after?

 Manipulation can provide a period of increased range in the joint that may have not been possible prior to the treatment. This increased range may allow for improved positioning or ease of movement in the joint or region of the body.^{12, 13}

There is also a decrease in specific hormones that are responsible for the regulating the inflammatory processes in the body. Less of these hormones circulating acts to minimize the pain felt in the joint.^{10, 11}

Lastly, manipulation also provides a quick stretch not just to the joint but also to the soft-tissues supporting it: the muscles, ligaments and nerves. This quick stretch effects the receptors in that tissue serving to decrease pain and potentially increase joint position sense.^10,11,12 This essentially allows the receptors in the joint to function more effectively.

Additional Note:

In Canada, when seeking a physiotherapist whom has undergone training to perform spinal manipulation, look for the FCAMPT designation in their credentials. These therapists have completed rigorous examination and certification to safely perform spinal manipulation through the Canadian Academy of Manipulative Physiotherapists.

References:

1. Brodeur R. The audible release associated with joint manipulation. Journal of Manipulative Physiol Ther. 1995 Mar-Apr; 18(3): 155-164.
2. Gross A, langevin, P, Burnie SJ, Bedard-Brochu MS, Empey B, Dugas E, Faber-Dobrescu, Andres C, Graham N, Goldsmith CH, Bronfort G, Hoving JL, LeBlanc F. Manipulationand mobilisation for neck pain contrasted against an inactive control or another active treatment.
3. Fritz JM, Koppenhaver SL, Kawchuk GN, Teyhen DS, Hebert JJ, Childs JD. Preliminary Investigation of the Mechanisms Underlying the Effects of Manipulation. Spine. 2011;36: 1772-1781.
4. Herzog W. The biomechanics of spinal manipulation. J Bodyw Mov Ther. 2010 Jul;14 (3):280-6.
5. Pickar JG. Neurophysiological effects of spinal manipulation. Spine J. 2002;2: 357-371. Potter L, McCarthy C, Oldham J. Physiological effects of spinal manipulation: A review of proposed theories. Phys Ther Rev. 2005; 10: 163–170.
6. Rubinstein S, van Middelkoop M, Assendelft, WJ, de Boer MR, van Tulder MW. Spinal Manipulative Therapy for Chronic Low-Back Pain: An Update of a Cochrane Review. Spine. 2011; 36:E825–E846
7. Walser RF, Meserve BB, Boucher TR. The effectiveness of thoracic spine manipulation for the management of musculoskeletal conditions: A systematic review and meta- analysis of randomized clinical trials. J Man Manip Ther. 2009;17(4): 237-246.
8. 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; 14:531 – 538.
9. Teodorczyk-Injeyan JA, Injeyan HS, Ruegg R. Spinal manipulation therapy reduces cytokines but not substance p production in normal subjects. J Manipulative Physiol Ther. 2006; 29 (1):14-21.
10. Degenhardt BF, Darmani NA, Johnson JC, Towns LC, Rhodes DC, Trinh C. Role of osteopathic manipulative treatment in altering pain biomarkers: a pilot study. J Am Osteopath Assoc 2007;107: 387–400.
11. Palmgren PJ, Sandstrom PJ, Lundqvist FJ, Heikkila H. Improvement after chiropractic care in cervicocephalic kinesthetic sensibility and subjective pain intensity in patients with nontraumatic chronic neck pain. J Manipulative Physiol Ther 2006;29:100-6.
12. Haavik H, Murphy B. Subclinical neck pain and the effects of cervical manipulation on elbow joint position sense. J Manipulative Physiol Ther. 2011;34(2): 88-97.

13. Biomechanics, Effects, Efficacy and Mechanisms of Spinal Manipulation: A Review of the Literature. Resource of the Canadian Academy of Manipulative Physiotherapists. pgs. 1-21.