Synovial Joints?

Many of our joints contain a lubricating fluid called synovial fluid surrounded by a fibrous capsule. These are called synovial joints and they make up a majority of our joints. Most important to me are the synovial joints of the spine which are called zygapophyseal or facet joints. They exist between the vertebrae and control or limit motion between adjacent vertebrae. There is a disc in there too which functions as both glue and shock absorber The disc is a joint itself, but is not the synovial type that us chiropractors are so interested in. Time to get physics-y. 

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Henry's Law?

There is a principal in physics called Henry's Law, undoubtedly named after its discoverer William Henry in the early 1800s. Henry's law describes how gasses may come out of a liquid solution under sufficient negative pressure. So how does this apply to our joints? Well, healthy synovial fluid contains nitrogen (a gas) in abundance. The nitrogen is, however, dissolved in the liquid solution that is our synovial fluid. I think you see where this is going.

 

Adjustment?

Thanks to some devine circumstances, the fibrous capsules that envelop our facet joints is stiff enough (in most people) so that a rapid decompression of the joint will create negative pressure sufficient to cause the nitrogen to escape the synovial fluid and become a gas. It literally forms into gas bubbles within the joint and depending on the amount it elicits a corresponding, and often audible, pop. 

 

This does a few important things:

• It widens the joint space taking pressure of of the sensitive joint surfaces.

• It dampens pain signals traveling up the spinal cord in a process called afferentation which was first postulated as Melzack and Wall's Gate Theory, 

• It helps release and remodel diseased joints.

• It improves range of motion.

• This list could go on but at the end of the day, It just feels good.

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Hopefully, you have a better idea of what an adjustment is and what it can do for you.

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See ya soon, Dr Malone

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