What is HSD?

Hypermobility spectrum disorders (HSD) are connective tissue disorders that cause joint hypermobility, instability, injury, and pain. Other problems such as fatigue, headaches, GI problems, and autonomic dysfunction are often seen as part of HSD.

What is hypermobility?

Joint hypermobility means that a person’s joints have a greater range of motion than is expected or normal.

Most babies and children are naturally very flexible. Many people become less flexible as they grow, but hypermobility continues into adulthood for some, up to about 20% of people. Being “flexible,” “bendy,” or “double-jointed” is not usually a problem, and for some, like dancers or gymnasts, it is an advantage. Hypermobility that does not cause pain or other symptoms is referred to as “asymptomatic joint hypermobility” and does not need to be treated.

The problem occurs when joints are not just hypermobile but are also unstable. Joint instability occurs when the bones of a joint aren’t held in place securely. This can lead to joint subluxations, dislocations, sprains, and other injuries. Joint instability can cause both acute and chronic pain and interfere with daily life.

Joint hypermobility and/or instability may be a person’s only problem. It can also occur as part of a known syndrome, such as types of Ehlers-Danlos syndromes (EDS), Marfan syndrome, or Down syndrome. The hypermobility spectrum disorders occur when a person has symptomatic joint hypermobility that cannot be explained by other conditions. A person with HSD may have joint instability as their only concern or may have other medical issues as well.

What is a disorder?

A medical disorder is defined as an illness or condition that disrupts normal physical or mental functions. If joint hypermobility causes problems that disrupt normal function, it is a disorder. If joint hypermobility isn’t causing any issues or pain, it is not considered to be a disorder.

What is a spectrum disorder?

A spectrum disorder refers to a condition that has wide variation in both the type and severity of symptoms people experience. For example, people with HSD may have mild or severe joint involvement. They may also experience one, two, or many other symptoms such as fatigue, dizziness, constipation, or headaches, and any of these problems may be mild or severe.

Two different people with HSD may experience very different symptoms. For example, one person with HSD may have severe joint instability, fatigue, and autonomic dysfunctionAnother person with HSD may have mild joint instability but severe headaches and gastrointestinal issues. Both people experience HSD differently, but neither person has “more HSD” than the other.  

How is joint hypermobility identified? 

Many people can recognize that their joints are able to move more than other people’s. A doctor or physical therapist can evaluate a person’s joints to determine if they are hypermobile. For some joints, a tool called a goniometer is used to measure how far the joint can extend. An experienced clinician can determine whether other joints move more than the normal range of motion.  

People may have joint hypermobility in one, a few, or many of their joints. Joint hypermobility is classified by which joints are affected. 

  • Generalized joint hypermobility: joint hypermobility present in many different joints throughout the body 
  • Peripheral joint hypermobility: joint hypermobility limited to the hands and feet 
  • Localized joint hypermobility: joint hypermobility in a single joint or group of joints in the same area 

One way to assess generalized joint hypermobility is with the Beighton Score, which measures joint hypermobility on a 9-point scale. One point is given for each of the following joints that show hypermobility on exam: 

  1. Base of the right 5th (pinky) finger 
  2. Base of the left 5th (pinky) finger 
  3. Base of the right thumb 
  4. Base of the left thumb 
  5. Right elbow 
  6. Left elbow 
  7. Right knee 
  8. Left knee 
  9. Lower spine 

A positive Beighton score is any score greater than or equal to 5/9 points in adults, 6/9 points in children (before puberty), and 4/9 points in adults over age 50. 

The Beighton score is a good screening tool for the likely presence of generalized joint hypermobility. However, people often have hypermobility in joints not measured by the Beighton score, such as the jaw, neck, shoulders, wrists, hips, ankles, feet, and toes. In these situations, only relying on the Beighton score is not enough. If a person has joint hypermobility in many different areas throughout the body this can also be classified as generalized joint hypermobility.   

What are the types of HSD? 

Four types of HSD are described, based on the type of joint hypermobility present. 

  • Generalized HSD (G-HSD): HSD in which joint hypermobility occurs throughout the body 
  • Peripheral HSD (P-HSD): HSD in which joint hypermobility is limited to the hands and feet 
  • Localized HSD (L-HSD): HSD in which joint hypermobility occurs in a single joint or group of joints in the same area 
  • Historical HSD (H-HSD): HSD in which there is history of generalized joint hypermobility, but without current evidence of generalized joint hypermobility on exam  

How common is HSD? 

We do not currently know the true prevalence of HSD. It is believed to be a common condition. (But unfortunately, it is not yet commonly diagnosed and treated!)  

How is HSD managed? 

The hypermobility spectrum disorders can cause a variety of symptoms in different areas of the body. Therefore, people with HSD may require multiple providers in different specialties to manage their care.  There are no disease-specific treatments for HSD, so HSD is managed by managing each individual’s symptoms. People with HSD may have very different symptoms and respond differently to different management strategies. Each person should work with their care team to develop a care plan that meets their individual needs. 

How is HSD diagnosed? 

HSD is diagnosed by medical history and physical examination. In the process, clinicians need to rule out other conditions that can cause the same symptoms. 

To be diagnosed with HSD, there should be evidence that the joint hypermobility is causing problems and it is not just an asymptomatic feature.

These problems include:  

  • Joint subluxations and/or dislocations 
  • Joint pain and loss of joint function 
  • Joint damage, such as cartilage tear 
  • Early joint degeneration (which may, over time, lead to significant wear and tear called osteoarthritis) 
  • Soft tissue (ligament/tendon) damage and injury 
  • Recurrent, persistent, and/or chronic pain 
  • Poor proprioception (reduced awareness of body’s position/movement) 

Other problems that often occur in people with HSD include:  

  • Fatigue 
  • Autonomic dysfunction 
  • Headaches 
  • Gastrointestinal problems 
  • Anxiety disorders 

There is no lab test or imaging study that can prove someone does or does not have a type of HSD. Therefore, it is important to rule out any other conditions that may be causing a person’s symptoms because management of those conditions may be different.  

Conditions that must be ruled out for an HSD diagnosis to be given include:  

  • The types of Ehlers-Danlos syndrome, especially hEDS 
  • Other heritable connective tissue disorders such as Marfan syndrome, osteogenesis imperfecta, Loeys-Dietz syndrome, Stickler syndrome, skeletal dysplasias 
  • Autoimmune rheumatic connective tissue disorders such as lupus, rheumatoid arthritis 
  • Chromosomal conditions such as Fragile X syndrome, Kabuki syndrome, Down syndrome 
  • Neuromuscular disorders that can cause joints to become unstable, such as multiple sclerosis and myopathies 

It is possible for someone diagnosed with HSD to then later develop another condition, such as lupus. In this case, they would have both an HSD and a lupus diagnosis. This is because at the time of the HSD diagnosis, there was no other explanation for the person’s hypermobility and symptoms. However, if someone who already has a lupus diagnosis would then develop symptoms like joint pain and instability, they would not be given a diagnosis of HSD. This is because there is another explanation for their hypermobility and symptoms (in this case, lupus). HSD can only be diagnosed when no other cause of a person’s symptoms can be found. 

Some people with HSD have additional features of other heritable connective tissue disorders but do not meet criteria for any known disorder. For example, someone with generalized joint hypermobility and chronic pain may also have features of hypermobile EDS such as atrophic scarring, stretch marks, hernias, and rectal prolapse, but they do not meet the 2017 diagnostic criteria. According to the current criteria, this person would be diagnosed with HSD. However, the problems they have would be managed the same way as they would be in someone with an hEDS diagnosis.  

A person’s diagnosis may change over time, as people may experience new symptoms that can change how their condition is classified. For example, a child may be diagnosed with HSD, but then later develops features such as mitral valve prolapse, stretch marks, atrophic scarring, hernias, and rectal prolapse. They would then meet the diagnostic criteria for hypermobile EDS and their diagnosis would change from HSD to hEDS. A person’s diagnosis could also change as research tells us more about hypermobility-related conditions. 

In 2017, the Ehlers-Danlos syndromes were reclassified and the hypermobility spectrum disorders were introduced. Joint hypermobility syndrome (or benign joint hypermobility syndrome) is an outdated diagnosis that should no longer be used. Most people who were previously diagnosed with joint hypermobility syndrome are now classified as having either hEDS or a type of HSD. 

Since there is not yet a definitive diagnostic test for HSD or for hEDS, there is no way to absolutely differentiate between the two conditions. 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.  

It is possible that hEDS and HSD have different underlying causes and that they are truly distinct from each other and from other disorders. It is also possible that hEDS and HSD have a common underlying cause and are not truly separate conditions.  

While it is frustrating to not have all the answers yet, this is not unusual. The history of medicine is full of examples of developments in diagnostic criteria and separation of conditions within the same family of disorders as knowledge grows. The hEDS/HSD Working Group of the International Consortium on EDS and HSD is continuing to research and gain better understanding of these conditions.  

At present, the principles and types of management are the same for both HSD and hEDS. Both conditions need awareness, recognition, validation, and care. It is fundamentally important that clinicians worldwide know that there are management strategies for both HSD and EDS that can improve the lives of people living with these conditions.  

We are delighted to be hosting the EDS ECHO Summit Series: Hypermobility Spectrum Disorders virtual event on April 1, which will cover all aspects of hypermobility spectrum disorders (HSD) with presentations, research, and management information from leading experts. A comprehensive event program will include presentations on topics including:

  • Pediatric and Adolescent Types of HSD
  • Movement Therapy and Training
  • Dental and Facial Pain in HSD
  • Lifestyle Strategies and Self-Pacing
  • Coping With Autonomic Symptoms

Learn more, register, or apply for a scholarship to attend here.

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