What is HSD?

Hypermobility spectrum disorders (HSD) are connective tissue conditions characterized by excessive joint mobility, instability, frequent injuries, and pain. These disorders are often accompanied by other symptoms such as fatigue, headaches, gastrointestinal (GI) issues, and autonomic dysfunction.

Joint hypermobility in HSD can result in subluxations, dislocations, sprains, and other injuries. It may occur independently or as part of recognized syndromes like Ehlers-Danlos syndromes (EDS), Marfan syndrome, or Down syndrome. HSD is diagnosed when symptomatic hypermobility cannot be attributed to other conditions.

How is Joint Hypermobility Assessed?

A common tool for assessing generalized joint hypermobility is the Beighton Score, which evaluates mobility on a 9-point scale. Points are assigned for hypermobility in the following joints:

• Fingers: Base of the right and left pinky fingers

• Thumbs: Base of the right and left thumbs

• Elbows: Right and left elbows

• Knees: Right and left knees

• Lower Spine

A score is considered positive for hypermobility if it meets or exceeds these thresholds:

• Adults: ≥5/9 points

• Children (pre-puberty): ≥6/9 points

• Adults over 50: ≥4/9 points

  
  

The Beighton Score is a useful screening tool but has limitations. Many individuals experience hypermobility in areas not included in the score, such as the jaw, neck, shoulders, hips, ankles, and feet. Beighton score limitations in selected populations, such as the very young and the elderly. Generalized joint hypermobility may be diagnosed if hypermobility affects multiple areas of the body, even without meeting the Beighton Score criteria.

How is HSD Diagnosed?

Diagnosis involves a detailed medical history and physical examination, with clinicians ensuring that symptoms are not caused by other conditions. Disorders that must be ruled out include:

• Heritable connective tissue disorders: Ehlers-Danlos syndromes (especially hypermobile EDS), Marfan syndrome, osteogenesis imperfecta, Loeys-Dietz syndrome, Stickler syndrome, skeletal dysplasias.

• Autoimmune rheumatic disorders: Lupus, rheumatoid arthritis.

• Chromosomal disorders: Fragile X syndrome, Kabuki syndrome, Down syndrome.

• Neuromuscular disorders: Multiple sclerosis, myopathies.

A diagnosis of HSD requires evidence that joint hypermobility causes significant problems, including:

• Joint subluxations or dislocations.

• Persistent pain or loss of joint function.

• Joint damage, such as cartilage tears or early degeneration (leading to osteoarthritis).

• Soft tissue injuries (ligament or tendon damage).

• Chronic pain or impaired proprioception (awareness of body position/movement).

Other common symptoms of HSD include:

• Fatigue.

• Autonomic dysfunction.

• Headaches.

• GI issues.

• Anxiety disorders.

Is There a Difference Between HSD and hEDS?

Currently, there is no definitive test to differentiate HSD from hypermobile Ehlers-Danlos syndrome (hEDS). Experts have varying perspectives:

• Some view HSD and hEDS as part of the same spectrum.

• Others regard them as distinct conditions.

It remains uncertain whether HSD and hEDS have different underlying causes or if they represent variations of the same disorder. Some experts believe that HSD and hEDS are in essence the same condition along a spectrum, some are not sure, and others think that HSD and hEDS are separate, distinct conditions.  

References

Ehlers-Danlos Society. "What Is HSD?" Ehlers-Danlos Society, www.ehlers-danlos.com/what-ishsd/#:~:text=Hypermobility%20spectrum%20disorders%20(HSD)%20are,seen%20as%20part%20of%20HSD. Accessed 3 Dec. 2024.