Mechanism of Action of Spinal Manipulation

 

Spinal manipulation therapy results in:

• Facet joint (zygapophyseal or Z-joint) separation which is accompanied by a release of pressure within the joint and usually an audible cavitation or "popping noise".

• Stretching of the paraspinal musculature that results in muscle relaxation (for which the mechanism has yet to be uncovered).

• Decreased intradiscal pressure (particularly affecting the annulus and endplates, which when under pressure may activate nociceptive receptors that propagate pain).

• Rise in beta endorphin (short-term analgesic effect after manipulation).Inhibition of afferent presynaptic pain (spino-thalamic tract) via mechanoreceptor activation, therefore providing short-term cutaneous pain relief.

 

1) "Review: Mechanism of Action of Spinal Manipulation Therapy." J Maigne, P Vautravers. Joint Bone Spine. 2003;70:336-341.

 

Based on pre and post MR Imaging of the lumbar spine, patients who underwent side-posture manipulation of the lumbar spine exhibited gapping of the Z-joints that was not present prior to the manipulative procedure. Side-posture position in and of itself also produced gapping of the Z-joints, but less than those who received manipulation.  Click here to see a video demonstration.

 

2) "The Effects of Side-Posture Positioning and Spinal Adjusting on the Lumbar Z Joints: A Randomized Controlled Trial with Sixty-Four Subjects." G Cramer, D Gregerson, JT Knudsen, B Hubbard, L Ustas, J Cantu. Spine. 2002;27(22):2459-2466.