Among his other cool abilities, a DC Comics superhero named Plastic Man can bend floppily in any direction. It’s a (made-up) talent that (real-life) double-jointed people might relate to. They can bend and stretch like they’re made of Silly Putty. They don’t have two joints in one. They’re hypermobile. Lots of kids have hypermobility that they outgrow.
Our joints are where two bones come together. One bone ends in a rounded shape. It fits into the other bone, which ends in a socket, like a ball in a catcher’s glove. If the socket is shallow, your joint could be very loose, giving you a lot of motion. This kind of hypermobility is common in our shoulders and helps baseball and tennis players swing hard and fast.
Ligaments wrap around our joints to hold them together as we move. If these ligaments are extra stretchy, that’s another way joints can be hypermobile. Dancers and gymnasts might have this kind of hypermobility in their hips and knees.
Cool as hypermobility is, we should try not to overstretch, even if it doesn’t hurt. Over time it can lead to painful conditions like your joints slipping out of place . . . which isn’t fun at all.
Bryson Lesniak, associate professor of orthopaedic surgery at Pitt, helped us bone up on hypermobility.
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