This is a really common question we get asked – “what’s the cracking noise?”
First off – it’s nothing to worry about. I always explain it’s not bone on bone, or anything popping back in. When the pressure within a joint space is reduced it alters the way the gases within the synovial fluid behave – they form a bubble which makes a ‘pop’ and is amplified through the bone. This video is a really great, clear explanation: why joints crack
Because of this popping sound people often assume that something has ‘popped back in’, but this is not the case; we don’t pop joints or discs back in (that’s anatomically impossible). The one exception to this is the joints where the ribs join the spine – these can become subluxed (partially dislocated) and we can ‘pop them back in’ sometimes.
The click of a joint is actually NOT what improves the joint function – it’s just a side effect. So it doesn’t matter if your joint clicks or doesn’t click during spinal manipulation. In-fact there are some techniques we use where we would never expect a click but we still see improvements. What improves the joint function is the neurological effect of the specific, quick, controlled impulse we apply to the joint. This quick movement fires off lots of little nerve endings within & surrounding the joint (mechanoreceptors) which sends signals up to the brain, improving feedback from that joint.