Have you ever wondered what is happening when your joints click, crack or pop, either in normal everyday life or when they are specifically manipulated during treatment. Clicking joints can give us an immediate sense of relief and release, making us feel so much better, but what is actually happening in the joint when you click them and why does it feel so good? Is joint clicking safe and does it cause arthritis?

What actually happens in the joint when it is clicked?

Joints are made up of two bone surfaces covered in cartilage with something called synovial fluid in between which helps them glide over each other when they move. Surrounding all of that is a capsule to hold the fluid in and some ligaments to keep the bones together. When we get a click from a joint, essentially we are pushing or pulling those joint surfaces apart, gapping them. The synovial fluid inside cannot expand so it gets depressurised to a point that any gas dissolved vaporises out creating a gas cavity in a process called tribonucleation. The fluid is made up of about 15% dissolved gas mainly carbon dioxide, and vaporisation of this gas allows the surfaces of the joint to suddenly move much further apart. The click or pop is the sound of the fluid snapping back.

Why does it feel good to click joints?

There are several reasons why this feels so good. As the surfaces of the bones move further apart, this stretches the capsule and ligaments surrounding the joint, which allows the joint to move more freely. The increased space between the bony cartilaginous surfaces then allows more free movement of the synovial fluid, further improving movement of the joint. Production of more synovial fluid is also stimulated. When joints surfaces are held very close together for a long period of time the synovial fluid cannot circulate as effectively as it should and can become more viscous or thicker. The newly invigorated production of synovial fluid re-sets this balance. Finally, as the ligaments are stretched they send a reflex signal to the brain which causes local muscle relaxation in the area surrounding the joint. All of which gives us an immediate feeling of release and relief. Though it must be remembered that this is temporary, and the increased joint movement can only be maintained by regular movement.

How safe is joint clicking?

Generally joint clicking is incredibly safe however problems can arise when one joint is clicked too much. If we continuously click the same joint everyday, the ligaments become stretched too much, meaning they are less able to hold the joint together in a stable position. Continuous daily clicking has been shown to increase the possibility of hypermobility in that joint. And if we have one hypermobile joint, the joints around it become stiffer because they do not need to move as much. In addition the muscles surrounding that joint have to tighten up to control the hypermobile joint. So counterproductively, continuous daily clicking of joints can promote stiff joints and tight muscles. Its a catch-22 that is difficult to break, because stiff joints and tight muscles feel relieved when you click that joint but clicking can be causing the problem. This is especially prevalent in women due to oestrogen which tends to relax ligaments, making this cycle more likely. The good news is that clicking the same joint up to 3 times a week hasn’t shown any long term increase in hypermobility.

Oh…..and there is no evidence at all that cracking your fingers causes arthritis, that is definitely an old wives’ tale!