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What Causes The Cracking Sound?

Picture of cracking knuckles

Before we go through what actually causes that "cracking sound". Lets take a deep dive into this ancient therapy that has taken over Youtube. 

What is the history of spinal cracking?


Spinal manipulative therapy actually dates much further back than a century. "Historical reference to Greece provides the first direct evidence of the practice of spinal manipulation. The detail in which this is described suggests that the practice of manipulation was well established and predated the 400 BCE reference". So it really is pretty ancient. It was popularised in the 1800s by a man called Andrew Taylor Still who was the founder of Osteopathy. Chiropractic branched from osteopathy and the rest is history. If you want to know more about the history of joint cracking click HERE.

What is cracking actually called?

The cracking we do has many names. Chiropractors themselves rarely call it a "crack" but rather spinal manipulation, a chiropractic adjustment, cavitation, pop, or a spinal realignment. Osteopaths may call it joint mobilisation and articulation. YouTube has popularised spinal manipulation through crack compilation videos.


Is cracking joints effective?

Most joints in the body can click. Ever noticed your feet and ankle click when you get out of bed in the morning? Many people think we just crack the neck and back but if warranted we can manipulate all of the joints in the body. In short spinal manipulation is effective for pain and stiffness. We crack a joint, tension is released and joint range of motion is increase. This has a positive effect on the nervous system. When we perform a spinal manipulation when are thrusting very quickly into a joint that stretches the joint capsule creating a cavitation. The thrust is performed at a fast and controlled speed that stimulates muscle receptors (mechanoreceptors) resulting in a relaxation of the area.

What does a crack feel like?

When I had my first spinal manipulation I was a little nervous. When people think of cracking the neck they often think of Rambo breaking necks. I am glad to say an adjustment feels great! You feel an instant relief of pressure. Often pressure you did not know that was there. It can feel like a warm sensation and feeling lighter is really common. People notice they can move more and have a reduction of pain. The effects can be temporary though. Spinal manipulation is perfect for reducing pain and then giving them rehab to strengthen the area to have a more long-term pain relief. In simple terms, spinal manipulation gives us a time gap to fit in exercises a patient may not have been able to do before. People reports sleep and digestion has improved but there is little research on that currently. It is very rarely painful. It is important to do a thorough examination before spinal manipulation. Some people are not suitable which is why we spend 4 years getting our basic degree. 

Chiropractor Cardiff, what causes the cracking sound in joints

Who Cannot have cracking?


For most patient, spinal manipulation is suitable and effective. There are unfortunately some people that are not suitable. You can see the list from WHO (world health organization) below:


"1. anomalies such as dens hypoplasia, unstable os odontoideum, etc.

2. acute fracture

3. spinal cord tumour

4. acute infection such as osteomyelitis, septic discitis, and tuberculosis of the spine

5. meningeal tumour

6. haematomas, whether spinal cord or intracanalicular

7. malignancy of the spine

8. frank disc herniation with accompanying signs of progressive neurological deficit

9. basilar invagination of the upper cervical spine

10. Arnold‐Chiari malformation of the upper cervical spine

11. dislocation of a vertebra

12. aggressive types of benign tumours, such as an aneurismal bone cyst, giant cell tumour, osteoblastoma or osteoid osteoma

13. internal fixation/stabilization devices  

14. neoplastic disease of muscle or other soft tissue

15. positive Kernig’s or Lhermitte’s signs

16. congenital, generalized hypermobility  

17. signs or patterns of instability

18. syringomyelia

19. hydrocephalus of unknown aetiology

20. diastematomyelia

21. cauda equina syndrome".

What causes the cracking sound?

Joints have what's called a synovial membrane that stabilises and creates the structure of a joint. This synovial membrane attaches to the articular surfaces of bone. The fast force of the spinal manipulation creates what is called a cavity, by momentarily separating the articular surfaces. This formation of a cavitation creates a vacuum and the pop, or cracking sounds. There is a scientific term for this, called tribonucleation. You can compare it to opening a can of fizzy drink. It used to be thought that it was the collapse of air bubbles that creates the sounds but its actually, the formation of them. 


Why do joints crack on their own?

It is perfectly normal for joints to click on their own. As we age it happens even more so. If you have tight muscles connected to a joint then extra pressure can cause a muscle-tendon to rub over a bone and cause popping sounds. You might stand up and your feet or ankles click. The same with your knees. Most cases are painless. If you notice swelling around the joints with painful clicks then it's worth a trip to your doctor. 

Is clicking my knuckles bad?

Cracking your knuckles is not bad for you and does not cause arthritis. Cracking joints increases mobility, so if someone is overzealous then the fingers may be prone to injury. Moderation folks!

Why do joints "crack" on their own?​
What causes the "cracking" sound?
Who Cannot have "cracking"
What does a crack feel like?
Is cracking joints effective?
What is "cracking" actually called?
What is the history of "cracking"?
is clicking bad
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