Disease of the month: Hypermobility syndrome

It’s a term being seen more often on insurance applications – so what is it and what risk does it pose? Mary Randell explains

Hypermobility means the muscles, tendons and ligaments around the joints are more supple than usual, allowing the joints to stretch further than normal. For example, some hypermobile people can bend their thumbs backwards to their wrists or put their legs behind their heads.

These acts are often called ‘double jointedness’, but this term should not be taken literally as an individual with hypermobility does not have two joints where everyone else just has one.

The condition can affect one or all of the joints. In most cases, the joint hyperlaxity is mild and does not affect everyday life, nor does it cause problems or symptoms.
However, in more severe cases of ­hypermobility, a number of symptoms may be experienced including myalgia and arthralgia and this is when a diagnosis of hypermobility syndrome may be made.

Causes

The condition often runs in families and there may be a genetic link for some forms of hypermobility. More females are affected than men and it usually results from one or more of the following:

• Abnormally shaped ends of bones at a joint, such as a shallow hip or shoulder socket
• Abnormal joint proprioception – an inability to determine where in space parts of the body are or how stretched a joint is
• Muscle tone weakness, resulting in joints only being held loosely in place
• Weak or stretched ligaments caused by altered protein fibres, elastin (which gives elasticity) and collagen (which gives strength).

Symptoms

Hypermobility syndrome may cause some or all of the following symptoms:

• Joint instability causing frequent sprains, tendonitis or bursitis
• Chronic joint pain, including back pain, prolapsed discs or spondylolisthesis
• Dislocations, especially shoulders – this can be caused by an individual not realising they have ‘overstretched’ their joint
• Early onset of osteoarthritis due to wear and tear on joints
• Muscle fatigue – muscles work harder to compensate for weakness in ligaments that support the joints
• Chronic fatigue syndrome
• Nerve compression disorders such as carpal tunnel syndrome
• Clicking or locking joints
• Bruising easily
• Fibromyalgia.

Diagnosis

Hypermobility is also known to be a symptom of serious inherited connective tissue disorders such as Marfan syndrome, ­osteogenesis imperfecta and, in particular, ­Ehlers-Danlos syndrome. While rare, these conditions need to be ruled out when making a diagnosis of hypermobility syndrome.

The Beighton Score has been used for years to indicate widespread hypermobility. The score is measured by adding one point for each of the following nine manoeuvres:

• Placing flat hands on the floor with straight legs
• Left knee bending backward
• Right knee bending backward
• Left elbow bending backward
• Right elbow bending backward
• Left thumb touching the forearm
• Right thumb touching the forearm
• Left little finger bending backward past 90 degrees
• Right little finger bending backward past 90 degrees.

However, a high Beighton score does not in itself confirm an individual has hypermobility syndrome. For many years, medical professionals varied their interpretation of the results significantly when making a diagnosis of the condition, so an additional measure, known as the Beighton criteria, was introduced. This has been used in conjunction with the Beighton Score for the past ten years.