Inside your joints is a cushion called cartilage. What makes cartilage able to cushion forces on the joint is its hydrophilic nature, causing it to swell when muscles are activated (1). When muscles compress a joint the cartilage will puff up, spreading the load, protecting the joint. Reducing strain on the joint to less than 20% of muscle forces (1). When the cushion doesn’t work properly joints become overloaded. Without the cartilage joints are loaded 4x more.
Due to the nature of the cushion enlarging, and the fact there is a cushion on each side of the joint, the cushions can become enmeshed and/or stuck. Fixating or restricting the joint. Muscular forces onto the joint increase, creating a snowball effect of tightening up, between joint and muscles. Meaning the cartilage can’t work properly, joint loads significantly increase and muscles fatigue sooner, increasing joint wear, corrupting muscle memory.
The crack noise as a joint unsticks is technically known as Tribonucleation. Which is the slow build-up of bubbles as the cartilage tries to do its job but can’t because the joint is restricted in some way. During manual therapy when joint surfaces are unstuck the small bubbles form into a larger bubble. Sometimes heard as a crack.
Joints can crack or pop for other reasons too.
Researchers on the subject have found that hearing a pop sound during manual therapy is not associated with a greater decrease in pain (2). Maybe there’s more to it than the crunch and crack of joint separation (3). Learning a new normal and getting out of bad habits, takes repetition. Which is why your treatment plan is a series of visits and not one magic crunch or crack.
Look after your joints and muscles, book your consultation today.
References:
- Musculoskeletal Biomechanics Laboratory, Columbia University, New York.
- Moorman AC and Newell D (2022) Impact of Audible Pops Associated with Spinal Manipulation on Perceived Pain. CMT 30 Article Number 42
- https://youtu.be/aJLU-4M-hdE Video of Joint Separation.