Q: What does it mean to be double jointed? A: “Double jointed” is a colloquialism for hypermobile joints, meaning joints that are more flexible than normal.

Q: What does it mean to be double jointed?


A: “Double jointed” is a colloquialism for hypermobile joints, meaning joints that are more flexible than normal. There are no specific tests used to identify hypermobile joints; however, a scoring system to measure hypermobility has been developed. The Beighton score gives one point –– for a maximum score of 9, since the first four criteria below can be present on the right, the left or both sides –– for being able to do each of the following:




Bend your little finger backwards to a 90-degree angle

Bend your thumb to touch your forearm

Hyperextend your elbow 10 degrees past straight

Hyperextend your knee 10 degrees past straight

Bend forward and place your palms flat on the ground while keeping your knees straight

Twenty to 30 percent of people have at least one extra-flexible joint, and about 10 percent have up to three. In general, kids and younger adults have more flexibility than the elderly.


It is less common to have generalized joint hypermobility, typically defined as a Beighton score of 4 or more; this is diagnosed in about 1 percent of the population. Hypermobile joints are more common in athletes, even more so in ballerinas, gymnasts and certain other athletes.


Joints may have increased flexibility for several reasons:




The shape of the bones in an individual joint may allow extra movement.

The ligaments that secure the bones to each other may have increased elasticity.

The muscles may be less stiff (stretching or certain muscle relaxation exercises such as yoga can increase flexibility).

The sense of joint movement (proprioception) may be decreased, allowing the development of increased mobility from repeated over-stretching movements.

Most people with hypermobile joints have no problems from them, and this is more a curiosity than a medical problem. However, some people with hypermobility develop joint pain (possibly from wear and tear of their hypermobile joints) and may have an increased risk of developing osteoarthritis. They may also be at an increased risk of suffering joint dislocations, strains and sprains because the joint’s increased movement.


The most common reason people have hypermobile joints is “normal variation,” which means they just happen to have increased flexibility. Hypermobility is more common when there is a family history of it, suggesting a hereditary component in some cases. Certain stretching exercises and athletic activities can increase joint flexibility.


However, certain medical conditions can have hypermobile joints as a symptom/physical finding. For example:


Down syndrome is a genetic disorder where the patient has three copies of chromosome 21 –– normally, there are only two –– that affects about 1 in 500 births –– it is more common in certain situations, such as when the mother is over age 35. Many Down syndrome patients have decreased muscle tone and other bone/joint issues that can lead to hypermobility.


Marfan syndrome is a genetic condition, affecting about 1 in 5,000 people worldwide, where a protein called fibrillin-1 that makes up connective tissues in the body does not develop normally. Hypermobile joints can be a manifestation of this syndrome, which can have other complications such as eye problems and even weakening of the aorta (the main artery carrying blood from the heart), possibly leading to an aortic aneurysm and rupture, which can be fatal.


Ehlers-Danlos syndrome is a genetic condition of collagen (a protein found in connective tissues) development that has many sub-types (overall, it affects about 1 in 5,000 people) and manifests as hypermobile joints and extra-elastic skin that bruises easily.


Other rare syndromes that may have hypermobile joints include cleidocranial dysostosis and Morquio syndrome.


People with hypermobile joints who do not have any symptoms and do not have any clinical concerns for one of the medical conditions noted above should be educated to:




Do regular exercise to strengthen their joints and maintain good muscle tone.

Ensure they minimize the possibility of dislocations or other joint injuries.

Patients with joint symptoms may benefit from pain medications, physical therapy and/or physical support through joint bracing. When there is a concern for one of the medical conditions noted above, further testing may be indicated.


Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at DrHersh@juno.com.