"Double-Jointed": The Real Story

We have all seen it, and sometimes we envy the beautiful lines a "double jointed" dancer can produce. But what does "double jointed" really mean? Is it really a thing? Today, we investigate "double jointed-ness!"

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"Double jointed" is an informal description of hyper-mobility. People who are perceived as "really flexible" are oftentimes identified as "double jointed." But there is no such thing as being "double jointed." You do not have two joints. First, let's look at what's "normal" for a joint.

What is a joint?

The physical point where two bones connect. The word "joint" comes from the Latin word jungere that means "to join."

What makes a joint move?

Joints do not have the ability to move by themselves. It's simply two bones sitting there. Ligaments hold the bones together, and muscles are what give us the ability to move (and dance!) One end of the muscle attaches to the end of a bone, stretches over the joint, and attaches at the end of the other bone. When a muscle contracts - which is the only way a muscle can make our bodies move - it pulls the bones at the joint to enable us to move.

What is "normal" behavior for a joint?

There are eight load-bearing joints (the ankles, knees, hips and shoulders). The joints should be in a biomechanical state of balance. The bones need to be properly aligned, which is their strongest position. In this alignment, they are not fighting gravity, and they can produce the most force when needed.

What makes my joint "double jointed?"

To reiterate, there is no such thing as having double joints. You have only one joint, but you may be hyper mobile in this joint. Hypermobility means you can move beyond the normal range for the joint. This can mean: 1) The ends of one or more bones at the joint are abnormally shaped, 2) Your ligaments - which are holding the bones together - are loose, allowing them to go beyond proper joint alignment. 3) A defect in collagen formation of your ligaments, which causes them to be loose.

What is proper alignment for a knee joint

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Here is proper alignment of the knees. The leg axis goes straight through the femoral head, straight through the knee joint and straight into the foot. When gravity is pushing down on this joint, it is in its strongest position to work against gravity and hold us up in a vertical line.

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The middle ballerina has hyperextension in her knee. Her tibia extends beyond proper alignment with her femur, which puts a lot of unsafe pressure on the knee joint.

Tip for Dance Teachers: Tape an "X" behind the knee joint. When they go back into hyperextension, the tape will pull the skin. If they go too far back, too quickly, the tape will pull off of the skin completely. Sensory feedback will help the dancer understand where they need to "stop" to find proper alignment. (Idea from Sally Sevey Fitt).

Here are some other common problems with knees

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This picture shows two different types of improper knee alignment. Left side: Knock Knees. Right side: Bow legs. You can see the axis runs through the femoral head and into the foot, but it does not go through the knee joint. The weight distribution is now off. Knock knees places too much weight on the outside of the knee, while bow legs place too much weight on the inside of the knee.

What does hyperextension look like in the elbow?

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The elbow is made of three bones: the humerus, the radius and the ulna. Hyperextension is when the ulna is moving beyond the proper alignment with the humerus. This, like hyperextension of the knee, can cause injury.

But if it's bad, why is hyperextension viewed as desirable in ballet?

Moderate hyperextension of the knee is desirable in ballet because of the line it creates. First, the legs fit tightly into 5th position. Secondly, it makes it appear as if arabesques go on for centuries, creating a beautiful line which is complimented by the arch of the foot. But hyperextension can lead to injury due to weak external rotators. Dancers with hyperextension must be aware of their alignment and be sure to not lock their knees.

We all have individual differences...

In the way our bones are shaped.
In the way our ligaments connect the bones.
In the strength of our muscles.

This is why it's so important to be aware of your personal strengths and weaknesses, and how your body tends to align itself. Work to strengthen the weak muscles that are pulling your body into poor alignment. Work on your awareness of when a joint is "locked." Strive to understand biomechanical balance for your own structure.

For further reading:

Dance Kinesiology by Sally Sevey Fitt

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