What does it mean to be "double jointed"?

Question

What does it mean to be "double jointed"?

Answer 1

The term "double jointed" implies the wrong concept.  Some people, due to genetics, have extremely open joints which allows for their joints to have a greater range of motion.  

There are no double joints.

Answer 2

It means that the joint can bend both ways, or in many more ways than a conventional joint.

Hinge joints, for example, can only bend in one direction. If the person is double-jointed in their elbow, for example, they can bend their forearm in both directions.

Answer 3

Hypermobility (also called double-jointedness, hypermobility syndrome or hyperlaxity) describes joints that stretch farther than is normal. For example, some hypermobile people can bend their thumbs backwards to their wrists, bend their knee joints backwards, or put their leg behind the head.

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