Voluntary joint dislocation

How it works

A joint is held together by its shape, by a capsule of tough tissue around it, by ligaments, and by the muscles that cross it. A subluxation is a partial slip, where the bone surfaces lose some contact. A dislocation is a full separation³. In most people both need force from outside, such as a fall.

Some people can do it on purpose. The shoulder is the usual joint, because its socket is shallow. The thumb, fingers, kneecap, and jaw come next. The person relaxes the muscles around the joint, pushes it in the loose direction, and lets it slip. It goes back with a pull or a shrug.

This needs unusually loose ligaments. About 20% of people have some degree of joint hypermobility, meaning their joints bend further than average¹. Voluntary dislocation is much rarer. It is often a sign of a connective tissue disorder, most often one of the Ehlers-Danlos syndromes. In these inherited conditions the collagen that gives ligaments their strength is weaker or more elastic than normal².

Is it a problem?

Popping a joint out is not an emergency if it goes back easily and does not hurt. It is still not free. Each slip stretches the ligaments a little more and can scrape cartilage. Over years this leads to a joint that slips on its own, to pain, and to early arthritis³. Nerves and blood vessels run close to most joints and can be pinched.

See a doctor if a joint slips out often, if it hurts, if it will not go back, or if your joints are loose all over. A doctor can check for hypermobility and for Ehlers-Danlos syndrome, and can suggest ways to keep the joint stable¹. Doing it for an audience is a poor trade.

History and culture

In the 1987 film Lethal Weapon, the character Martin Riggs dislocates his own shoulder and slams it back into place⁴. The scene made the trick famous. It is not a good example to copy.