Hypermobility and Ehlers-Danlos Syndrome: Understanding Differences, Diagnosis, and Management

What is the difference between hypermobility and EDS?

While both terms relate to increased joint range of motion, hypermobility simply describes joints that extend beyond typical limits, whereas Ehlers-Danlos Syndrome (EDS) is a group of inherited connective tissue disorders characterized by widespread tissue fragility, of which hypermobility is often a prominent, but not the sole, feature.

Understanding Joint Hypermobility

Joint hypermobility, often colloquially referred to as "double-jointedness," describes the ability of a joint to move beyond its normal anatomical range of motion. This is a common trait, found in a significant portion of the general population, particularly during childhood and adolescence, and is more prevalent in females.

Causes of Hypermobility:

• Genetic Factors: Variations in collagen production or structure, which affects the elasticity and strength of connective tissues like ligaments and joint capsules.
• Anatomical Differences: Shallow joint sockets or abnormally shaped bones can contribute.
• Muscle Tone: Lower muscle tone can allow for greater passive range of motion.
• Training: Activities like gymnastics or ballet can increase flexibility, potentially leading to acquired hypermobility.

For many individuals, hypermobility is benign, meaning it causes no pain, instability, or functional limitations. However, in some cases, hypermobility can lead to symptoms such as joint pain, stiffness, fatigue, and an increased propensity for sprains or dislocations. When hypermobility is symptomatic but does not meet the criteria for a more complex connective tissue disorder like EDS, it is often classified as Hypermobility Spectrum Disorder (HSD).

Delving into Ehlers-Danlos Syndromes

Ehlers-Danlos Syndromes (EDS) are a group of heritable connective tissue disorders primarily affecting collagen, the most abundant protein in the body, which provides strength and elasticity to skin, bones, blood vessels, and many other organs. There are 13 recognized types of EDS, each caused by specific genetic mutations that lead to defects in the synthesis or processing of collagen or proteins that interact with collagen.

Key Characteristics of EDS:

• Systemic Nature: Unlike isolated joint hypermobility, EDS is a systemic disorder, meaning it affects connective tissue throughout the entire body, not just the joints.
• Multi-systemic Manifestations: While joint hypermobility is a hallmark feature in many types (especially hypermobile EDS, hEDS), individuals with EDS often experience a wide range of other symptoms, including:
  • Skin hyperextensibility: Skin that is soft, velvety, and easily stretched.
  • Tissue fragility: Easy bruising, slow wound healing, atrophic scarring (thin, wide scars).
  • Vascular complications: Fragile blood vessels (particularly in vascular EDS, vEDS), leading to aneurysms or organ rupture.
  • Autonomic dysfunction: Conditions like Postural Orthostatic Tachycardia Syndrome (POTS).
  • Gastrointestinal issues: Dysmotility, reflux.
  • Chronic pain and fatigue: Often debilitating.
  • Pelvic organ prolapse, hernias, dural ectasia: Due to weakened connective tissue support.

The most common type, hypermobile EDS (hEDS), is characterized by generalized joint hypermobility, chronic pain, and other systemic manifestations, but currently lacks a specific genetic marker, making its diagnosis primarily clinical. Other types, like classical EDS (cEDS) or vascular EDS (vEDS), have distinct genetic mutations and often more severe organ-specific involvement.

The Critical Distinction: Hypermobility vs. Hypermobility Spectrum Disorder (HSD) vs. Ehlers-Danlos Syndrome (EDS)

The relationship between these terms can be confusing, but understanding the spectrum is crucial:

• Joint Hypermobility (JH): This is the broadest term, simply indicating increased range of motion in one or more joints. It can be asymptomatic (benign) or symptomatic.
• Hypermobility Spectrum Disorder (HSD): This diagnosis is given when an individual experiences symptoms (e.g., pain, instability, fatigue) related to their hypermobility, but their condition does not meet the strict diagnostic criteria for any specific type of Ehlers-Danlos Syndrome. HSD represents a symptomatic end of the hypermobility spectrum that is not EDS.
• Ehlers-Danlos Syndrome (EDS): This is a specific group of inherited connective tissue disorders. While generalized joint hypermobility is a key feature of many EDS types (especially hEDS), the diagnosis of EDS requires the presence of additional specific systemic criteria, indicating widespread connective tissue fragility beyond just the joints. This includes characteristic skin findings, tissue fragility, and other organ system involvement. Genetic testing can confirm many types of EDS, but hEDS remains a clinical diagnosis.

Key Differentiating Factors:

• Scope: Hypermobility is a localized joint finding; EDS is a systemic disorder affecting the entire body's connective tissue.
• Severity/Impact: Benign hypermobility has no negative impact. HSD causes symptomatic joint issues. EDS often leads to widespread, multi-systemic complications and significant disability due to pervasive tissue fragility.
• Underlying Cause: While both involve connective tissue, EDS has specific, often identified, genetic mutations affecting collagen structure or processing. Hypermobility can be multifactorial.
• Diagnosis: Hypermobility is assessed with tools like the Beighton Score. HSD is a clinical diagnosis based on symptomatic hypermobility not meeting EDS criteria. EDS diagnoses follow strict, specific criteria, often requiring genetic testing for types other than hEDS.

Diagnostic Approaches

Diagnosis of hypermobility is typically made through a physical examination, often utilizing the Beighton Score, which assesses the flexibility of five specific joints bilaterally (pinky finger, thumb, elbow, knee, and trunk flexion). A score of 4 or more out of 9 often indicates generalized joint hypermobility.

Diagnosing Ehlers-Danlos Syndromes is more complex. It involves:

• Comprehensive Clinical Assessment: Evaluation of the Beighton Score, skin characteristics, scarring, presence of hernias, organ prolapse, and a detailed family history.
• EDS-Specific Diagnostic Criteria: Each type of EDS has its own specific diagnostic criteria developed by international consortia.
• Genetic Testing: For most types of EDS (excluding hEDS), genetic testing is crucial to confirm the specific gene mutation and subtype, which informs prognosis and management.

Implications for Exercise and Management

For individuals with hypermobility, HSD, or EDS, exercise plays a critical role in management, but approaches must be tailored to the individual's specific condition and symptoms.

For Benign Hypermobility:

• Focus: General fitness, strength, flexibility, and proprioception.
• Considerations: Awareness of joint end-ranges; avoiding hyperextension during exercises is prudent to prevent unnecessary strain.

For Hypermobility Spectrum Disorder (HSD) and Ehlers-Danlos Syndromes (EDS): Exercise must be approached with caution and often under the guidance of a physiotherapist or exercise physiologist experienced with connective tissue disorders.

• Prioritize Stability over Flexibility: The goal is to build strength around the joints to improve stability and proprioception (body awareness), rather than increasing flexibility, which is already excessive.
• Low-Impact Activities: Swimming, cycling, elliptical training, and walking are often preferred to minimize joint stress.
• Strength Training: Focus on controlled, slow movements with lighter loads. Emphasize eccentric control and isometric holds. Avoid ballistic movements or exercises that push joints into their end-range of motion.
• Proprioceptive and Balance Training: Crucial for improving joint awareness and reducing the risk of sprains and dislocations. Examples include single-leg stands, balance boards, and unstable surface training.
• Core Stability: A strong core is fundamental for overall body stability and reducing strain on peripheral joints.
• Pacing and Energy Conservation: Individuals with HSD and EDS often experience chronic pain and fatigue. Exercise programs must incorporate rest days and gradual progression.
• Avoidance: High-impact activities, heavy lifting that strains joints, and extreme stretching should generally be avoided.
• Multidisciplinary Approach: Management of EDS often requires a team approach involving rheumatologists, geneticists, cardiologists, gastroenterologists, physical therapists, and occupational therapists. Exercise professionals are key members of this team.

Conclusion

While joint hypermobility is a common physical trait, its distinction from Hypermobility Spectrum Disorder and, more significantly, from Ehlers-Danlos Syndromes, is crucial for accurate diagnosis, appropriate management, and understanding potential systemic health implications. As fitness professionals, recognizing this spectrum allows for tailored, safe, and effective exercise interventions that prioritize joint stability, pain management, and overall functional improvement for individuals with these complex conditions.