Benign Hypermobility Joint Syndrome — or BHJS — is a common source of joint or muscle complaints by children and young adults. Benign hypermobility describes looseness of joints that may be associated with daytime pain, nighttime awakening, or discomfort after exercise. Children or young adults with hypermobility usually have joint pain and occasionally mild swelling during the late afternoon, at night, or after exercise or activity. The pain is more common in the lower extremities, such as the calf or thigh muscles. It most often involves large joints such as the knees or elbows, but can involve any joint.

BHJS seems to occur more often in Asian-American children than in Caucasian children, and it is least common in African-American children. When large groups of school children are tested, BHJS is found in as many as 40% of them. About 10% of these children have hypermobility that can lead to pain after activities or at night.

Assessment of children or young adults suspected of having BHJS does not require special equipment. Testing the range of motion of your child’s joints will determine if they are more loose than normal. Several specific mobility tests are used for diagnosing BHJS, 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 his or her palms flat on the floor.

Treatment for BHJS is specialized for each child or young adult, based on his or her overall health, medical history, severity of pain or discomfort, and presence of other symptoms. It can include:

Exercise. Basic strengthening and guided exercise programs can help your child reduce flexibility and increase muscle strength to help prevent future injury. Strengthening exercises and conditioning activities — such as swimming, walking, and skating — help improve joint strength. Inactivity should be avoided. In addition, being overweight worsens the problem. Splints, braces, or taping may be recommended to protect affected joints during activity.
Joint protection. Practicing the following joint protection techniques can help your child avoid overstretching the joints at risk:
Avoid sitting cross-legged with both knees bent (“Indian style”).
Bend the knees slightly when standing.
Wear shoes with good arch supports.
Decrease those unusual joint movements that hypermobile children often use to entertain their friends.

BHJS rarely leads to arthritis later in life, although some people with the condition may develop shoulder or kneecap problems if there are frequent dislocations or if the cartilage around these or other joints becomes excessively worn. Individuals that have BHJS as adults are more likely to develop osteoarthritis or “wear and tear” arthritis as they age.