It turns out that being “double-jointed” isn’t really a thing. When someone describes themselves as being double-jointed, what they actually have is hypermobility. That’s when a person’s joints can move beyond the typical range of motion. We all have the exact same skeletal framework, but people with hypermobility have joints that just stretch and move beyond the typical baseline. That’s why double-jointedness isn’t a medical diagnosis but a sort of nickname for hypermobility. “I see patients every day who can bend their fingers backward, hyper-extend their elbows or knees, or move their shoulders in ways that seem impossible to most people,” said Dr. Jacques Courseault, a physical medicine and rehabilitation physician, and assistant professor at Tulane University School of Medicine. “They don’t have additional joints. Their joints simply have greater mobility because of differences in the connective tissues that support them.” It might surprise you to learn that hypermobility is much more common than most people think. Doctors check for it with a quick test called the Beighton score. Can you bend your pinky finger back past 90 degrees, touch your thumb to your forearm, or put your palms flat on the floor without bending your knees? If so, you have hypermobility. What causes hypermobility? Genetics play a major role, as it tends to run in families. Meanwhile, many people grow out of hypermobility in the transition from childhood to adulthood. If flexibility comes with pain lasting more than a few months, joints that slip out of place without a real injury, easy bruising, soft or stretchy skin, or things like fatigue and dizziness when you stand, you'll need to talk to your doctor. The good news is that strength and balance training, done gradually, goes a long way.
