Is it possible to truly be double-jointed?

The freight train carrying hand-painted advertisements has come to a halt, with its eccentric passengers disembarking: elephants, clowns, a strongman, trapeze performers, a bearded lady, and other self-proclaimed oddities. The carnival has made its way to a small town in America.

As families pass through the entrance gates, various vendors eagerly vie for their attention and dollars. A family with young children debates their first stop, while nearby, some neighbors step out from a small tent, their eyes wide in amazement. Above the tent's entrance, the word "contortionist" is written in delicate red cursive.

Inside, an astounding performance begins, seemingly defying all logic and reason. The contortionist starts by lifting one leg and placing her foot behind her head. As she does this, she effortlessly rotates 180 degrees on the supporting leg. Now, with her leg suspended and her body facing the audience, she lowers her leg, brings her hands behind her back, and swings them over her head, placing her joined hands in front of her.

As the performance unfolds, it becomes apparent that the performer seems to be made of rubber, not bone. Her movements defy human limits, leaving the family and the audience in disbelief. Some viewers instinctively touch their elbows, wrists, and knees as if trying to understand the impossible flexibility they are witnessing.

While the performance is astonishingly unusual, it's not entirely one of a kind. Statistically, out of every 100 random audience members, about three people will have what we often refer to as double-jointedness [source: Elliott]. But what exactly does it mean to be double-jointed? Does it imply having two joints instead of the usual single one? Is there a joint that allows normal movement and another that provides extra flexibility, or does one joint simply malfunction? Step right up, folks, the fascinating world of double-jointedness awaits in the next section.

Double-what? Hypermobility

Before we dive into the concept of being "double-jointed" (which we'll unpack further shortly), it's important to first understand how a typical joint functions.

A joint is essentially where two bones meet, enabling one to move relative to the other. The ends of the bones are covered in cartilage to protect against damage when they come into contact. Ligaments and other connective tissues bind the bones together, while movement occurs through muscle contraction or extension. These muscles are linked to the bones by tendons.

Most joints have a typical range of motion. For example, your elbow lets you bend and straighten your arm. However, if you were to extend your arm beyond the point where it forms a straight line, it could cause a dislocation—a painful separation of the bones and ligaments holding them together.

Some individuals, however, possess a greater range of motion in their joints than others. While the term double-jointed is commonly used, it’s not entirely correct. The more precise terms are joint hypermobility or joint hyperlaxity. A person with hypermobility in their elbow, for instance, might be able to extend their arm by about 10 degrees beyond what most of us would call full extension.

How is this possible? Genetics plays a significant role, as the shape of ligaments and bone structure largely determines how much movement a joint can allow. Your hips and shoulders both feature ball-and-socket joints, where the end of one bone has a ball that fits into a cuplike space on the other. The deeper the ball sits in the socket, the more limited the range of motion; however, if the ball is shallow in the socket, the range increases. Some people can even roll the ball out of the socket and back in.

Many Degrees of Separation: Pros and Cons of Being Hypermobile

Joint hypermobility has its pros and cons. On the positive side, it could be a real asset for musicians or athletes. Imagine a pianist with hypermobile fingers and thumbs, or a gymnast with flexible hips or vertebrae. Other perks might include surprising your family at dinner or winning bets at the bar. However, maintaining this flexibility requires effort. Whether you're a concert pianist or just a casual enthusiast, regular stretching is essential to keep your joints flexible. Without it, your extra range of motion may decrease as you get older.

On the flip side (the more flexible one), hypermobility often comes at a cost. There's an increased risk of arthritis in hypermobile joints, particularly the fingers. Many people, especially younger individuals going through growth spurts, may experience significant joint pain. While some athletes may benefit from hypermobility, others with hypermobile joints are more prone to injury. A group of related conditions causing pain and discomfort is collectively known as hypermobility syndrome (HMS). It's important to note that having hypermobile joints doesn't automatically mean you have HMS, only if chronic pain is present, which affects a minority of those with hypermobility. Moreover, if you do suffer from HMS, there's a 50% chance that your children might also develop it [source: Grahame].

Interestingly, if you're capable of feats like putting both feet behind your head and walking on hyperextended arms while swinging your upper body between your elbows, you might find that local anesthetics aren't as effective on you as on those with more typical flexibility. Studies have shown that many hypermobile individuals experience little or no effect from local anesthetics, something you may want to inform your doctor about if you're scheduled for a medical procedure or are expecting a pregnancy.

So, while the term 'double-jointed' may not hold any real meaning, being hypermobile is a more accurate description. It simply means you have a little extra flexibility in everything you do.

For further details on hypermobility, bones, and joints, be sure to visit the next page.