What Is Hypermobility Joint Syndrome?

Medically Reviewed by Tyler Wheeler, MD on December 19, 2022
3 min read

Hypermobility joint syndrome (HJS) means your joints are “looser” than normal. It’s typically referred to as being double jointed.  It is a common joint or muscle problem in children and young adults, and is one of many connective tissue disorders.

Formerly known as benign hypermobility joint syndrome (BHJS), the condition can cause pain or discomfort after exercise. It’s usually not part of any disease.

Children or young adults with hypermobility have joint pain.

The pain is more common in the legs, such as the calf or thigh muscles. It most often involves large joints such as the knees or elbows. But it can involve any joint.

Some people also have mild swelling in the affected joints, especially during the late afternoon, at night, or after exercise or activity. That swelling may come and go within hours.

Other symptoms may include joint dislocation, thin skin, drooping eyelids, hernia, and varicose veins. 

Girls’ joints tend to be more mobile (looser) than those in boys of the same age. Younger children tend to report more pain. Teens may have fewer symptoms because their muscles and joints become tighter and stronger as they get older.

HJS seems to happen more often in Asian-American children than in Caucasian children, and it is least common in African-American children. The reasons for that aren’t clear.

When large groups of schoolchildren are tested, as many as 40% have the syndrome. About 10% of these children have hypermobility that can lead to pain after activities or at night. No one knows why some children feel that discomfort, while others with equally loose joints don’t have pain or swelling.

Loose joints run in families.

Simple tests show whether a child has a greater range of motion in their joints than normal. Doctors use several specific mobility tests, including:

  • The wrist and thumb can be moved downward so the thumb touches the forearm.
  • The little fingers can be extended back beyond 90 degrees.
  • When standing, the knees are abnormally bowed backward when viewed from the side.
  • When fully extended, the arms bend further than normal (beyond straight).
  • When bending at the waist, with the knees straight, the child or adult can put their palms flat on the floor.

Since the symptoms of hypermobility can sometimes mimic arthritis, you may need to get lab tests to make sure your child doesn’t have a more serious disorder (such as juvenile arthritis or other inflammatory conditions). In rare cases, you may need to get X-rays.

Simple things can help with this condition, such as:

Exercise. It’s a good idea to strengthen the muscles around loose joints. For some people, doctors recommend splints, braces, or taping to protect affected joints during activity.

  • Joint protection. These tips will help your child avoid overstretching their hypermobile joints:
    • Don’t sit cross-legged with both knees bent ("Indian style").
    • Bend the knees slightly when standing.
    • Wear shoes with good arch supports.
    • Stop any unusual joint movements that hypermobile children often use to entertain their friends.

Medications don’t fix loose joints. If pain after exercise is a problem, ask your doctor about over-the-counter anti-inflammatory drugs, such as ibuprofen or naproxen.

Children with loose joints often do well in activities that reward flexibility, such as cheerleading, modern dance, gymnastics, and ballet. (Those activities also require strength, of course.)

But they may need to stop or cut back on some of these hobbies if they are too painful or if your child dislocates a joint.

Most symptoms improve as children get older and stronger. Still, it lasts for some people.

The syndrome usually leads to arthritis later in life. But some people with the condition may get shoulder or kneecap problems if they often dislocate those joints or if their cartilage gets worn down.

People who have the syndrome as adults are more likely to get osteoarthritis  (“wear and tear" arthritis) as they age. A few people still have muscle pain from hypermobility as they become adults. They are more likely than others to have sprains, injuries, dislocations, occasional swelling, backaches, and discomfort after exercise.