Outline
A Framework for the Classification of Joint Hypermobility and Related Conditions
- Setting the Stage
- Defining Hypermobility
- Types of Joint Hypermobility
- Secondary Musculoskeletal Manifestations of Joint Hypermobility
- Classifying Joint Hypermobility
Hypermobility Spectrum Disorders
Other Important Comments Regarding Hypermobility Spectrum Disorders
Introduction
Hypermobility has had many names: Benign Joint Hypermobility Syndrome, Joint Hypermobility Syndrome, Ehlers-Danlos Syndrome Hypermobility type, Hypermobile EDS, Hypermobility Spectrum Disorders. Lots of terms that have sometimes been used interchangeably, some with more baggage than others. This website will be focusing on the Hypermobility Spectrum Disorders (HSDs) primarily, but it’s important to recognize two things:
- Hypermobility Spectrum Disorders do not exist in isolation. They are part of a broad range of disorders, including the Ehlers-Danlos syndromes (EDS) and Marfan Syndrome, of which hypermobility can be a clinical feature.
- Our understanding of Hypermobility Spectrum Disorders is evolving. Until March of 2017, they were characterized quite differently, with vague working terminology. As we learn more, our understanding will continue to change how we approach these disorders, maybe even what we call them, and that is a good thing because it means we are making progress.
Other websites cover the full history of Hypermobility and Ehlers-Danlos Syndrome (EDS), but my interpretation of the history and development of HSDs can be found here: “Hypermobility – A History”
A Framework for the Classification of Joint Hypermobility and Related Conditions
At the time of the 2016 Ehlers Danlos Society International Symposium, nearly 20 years since the Villefranche reclassification of EDS in 1997, in the face of scientific advances in the molecular understanding of EDS, leading experts decided it was time to once again update the EDS nosology.
The result was the publication of the 2017 EDS International Classification in the American Journal for Medical Genetics Part C: Seminars in Medical Genetics “Special Issue: The Ehlers-Danlos Syndromes: Reports from the International Consortium on the Ehlers-Danlos Syndromes.”
This page focuses on the seminal work related to Hypermobility Spectrum Disorders, which is available to read in full for free here: A Framework for the Classification of Joint Hypermobility and Related Conditions
I outline and quote from the article extensively in an effort try to put their conclusions into simple, concise terms.
Setting the Stage
“Joint hypermobility is a feature commonly encountered in many other disorders, both genetic and acquired, and this finding is attracting the attention of an increasing number of medical an non-medical disciplines. In this paper the terminology of joint hypermobility and related disorders is summarized. Different types of joint hypermobility, its secondary musculoskeletal manifestations and a simplified categorization of genetic syndromes featuring joint hypermobility are presented.”
“A group of hypermobility spectrum disorders is proposed as diagnostic labels for patients with symptomatic joint hypermobility but not corresponding to any other syndromes with joint hypermobility.”
Defining Hypermobility
- “Joint hypermobility (JH) is the term universally accepted to define the capability that joint (or group of joints) has to move, passively and/or actively, beyond normal limits along physiological axes.”
- “JH is a descriptor rather than a diagnosis.”
- “JH may exist as an isolated finding, but is often a feature of a larger syndromic diagnosis.”
- “Synonyms of JH include joint laxity and double-jointedness.. joint hyperlaxity is often considered a further synonym of JH”
- “Establishing whether a joint is hypermobile or not is a relatively easy task and it is carried out by
- (i) using professional tools, such as the orthopedic gonionmeter;
- (ii) following specific procedures (e.g. [Juul-Kristensen et al., 2007]); and
- (iii) comparing the measured range of motion (ROM) with normal parameters.”
- “Joint instability (JI) has in the past been used as a synonym of JH, However, JI by inference is a prelude to detrimental effect on the involved joint(s), while JH is a neutral term often defining a benign trait.”
- “Hypermobile joints may also be unstable, but JI is not a mandatory consequence of JH. Also the reverse is true: not all unstable joints are hypermobile.”
- “Instability arises from a number of pathologies including
- laxity in the supporting soft tissue structures;
- congenital or acquired abnormality of the joint articulation;
- muscle disorders (inherent or acquired weakness, and biomechanical imbalance); and
- musculoskeletal dysfunction as a result of neurological disorders.”
- “The lack of support puts an individual at increased risk of joint dislocations (luxations and subluxations), and articular and soft tissue injuries”
- “While JH is frequently a consequence of (either congenital or acquired) ligamentous (hyper-) laxity, the pathogenesis of JI is wider, as the propensity to joint dislocations, joint pain, and soft-tissue traumas may arise from a number of hereditary and acquired muscle and bone disorders.”
Personally, I don’t entirely agree with the logic used here to distinguish between joint instability and joint hypermobility. I understand the first part, that not all hypermobile joints are unstable, because not all hypermobile joints are symptomatic. In fact, for ballet dancers and the like, being able to move a joint beyond the normal range of motion can be seen as beneficial.
However, in my opinion, unstable joints are by definition hypermobile. In the paper they don’t even offer a definition of instability, just a list of potential causes. The causes are important to note, because they demonstrates that just because a joint is unstable does not mean it is caused by an underlying heritable connective disorder (HCTD), as with joint hypermobility itself.
However, this lack of definition I think leaves a lot of room open for questioning. For one thing, how do we even measure the level of a joint’s instability? And isn’t it the very instability of a hypermobile joint that is the root of all the subsequent musculoskeletal complications?
Wikipedia offers some insight into joint stability:
Joint stability refers to the resistance offered by various musculoskeletal tissues that surround a skeletal joint. Several subsystems ensure the stability of a joint. These are the passive, active and neural subsystems. It is believed that one or more of the subsystems must have failed if joint instability occurs, usually a torn or overstretched ligament. Instability of joints can cause unhealthy ranges of movement in your joints which can result in the joints fracturing.
I think that last sentence is very important. Instability leads to unhealthy ranges of movement. If we determine a joint’s hypermobility by measuring it’s range of motion and assessing how far it is out of the normal range of motion, and instability is the presence of unhealthy ranges of movement (perhaps even a subluxation or dislocation), then by definition, an unstable joint is hypermobile.
Perhaps that’s where part of the distinction comes from, that hypermobile joints are measured along “physiological axes.” I couldn’t find a very good definition for this phrase, either, but my best guess is that it means the movement that a joint is “supposed” to make. As opposed to joint instability, where the joint has excessive movement in a direction the joint isn’t supposed to move.
In my humble personal opinion, however, if a joint isn’t supposed to move in a particular direction, then the normal range of motion is 0, and anything in excess of that is hypermobile. I don’t think it should matter whether or not the movement is part of the joints usual movement or function.
As a quick aside, Joint Instability and Osteoarthritis is an article from the journal Clinical Medicine Insights Arthritis and Musculoskeletal Disorders available for free on PubMed that talks about some of the negative consequences of joint instability in more detail.
Types of Joint Hypermobility
The following outline is paraphrased from the article A Framework for the Classification of Joint Hypermobility and Related Conditions.
1. Localized Joint Hypermobility (LJH)
- JH at one or a few types of joints, usually fewer than 5
- Usually affects a single small or large joint
- May be bilateral (the same on both sides of the body)
- May be inherited
- May be acquired, for example due to trauma, joint disease, surgery, training
2. Generalized Joint Hypermobility (GJH)
- JH at multiple sites, usually 5 or more
- Theoretically simultaneously at the four limbs and axial skeleton (central body)
- Assessment isn’t always straightforward
- Several tools exist to measure, including the Beighton Score, but all have limitations (see “Measurement Properties of Clinical Assessment Methods for Classifying Generalized Joint Hypermobility – A Systematic Review“)
- Usually congenital, often inherited, can be acquired
3. Peripheral Joint Hypermobility (PJH)
- JH at hands and feet only
- Distinct from LJH because all 4 limbs involved
- Distinct from GJH because large, axial joints not involved
- Usually non-pathological, mild impact
- Possible clue to vascular EDS, which is associated with JH of small joints
4. Historical Joint Hypermobility (HJH)
Age reduces range of motion (ROM)
- Assessed by 5 point questionnaire for adults who have possibly lost their GJH, answer yes to any two of the following questions:
- Can you now (or could you ever) place your hands flat on the floor without bending your knees?
- Can you now (or could you ever) bend your thumbs to touch your forearm?
- As a child did you amuse your friends by contorting your body into strange shapes or could you do the splits?
- As a child or a teenager did your shoulder or kneecap dislocate on more than one occasion?
- Do you consider yourself double-jointed?
Secondary Musculoskeletal Manifestations of Joint Hypermobility
The following outline is summarized and paraphrased from the article A Framework for the Classification of Joint Hypermobility and Related Conditions.
- Trauma
- Macrotrauma
- dislocations, subluxations, or soft tissue injuries, such as damage to muscles, ligaments, tendons, synovium, cartilage
- result of isolated or recurrent trauma due to excessive movement along non-physiological axes
- can be compounded by joint instability
- Microtrauma
- silent injury not perceived as it occurs
- over time can predispose patient to pain and joint degeneration
- If recurring, both can lead to regional joint disorders, e.g. TMJ
- Macrotrauma
- Chronic Pain
- Possibly due to pain sensitization, hyperalgesia
- Possibly related to high rate of small fiver neuropathy seen in adults with common EDS subtypes
- Disturbed Proprioception
- When combined with loss of muscle strength, can lead to limitation of daily life activities
- Pes planus (“flexible” type) [flat foot]
- Valgus [outward angulation] deformity of the elbows, hindfeet and halluces [bunion]
- Scoliosis, not congenital, or a mild to moderate degree
- Accentuated dorsal kyphosis [excessive forward rounding of the upper spine] and lumbar lordosis [excessive inward curvature of the lower spine]
- Deformational plagiocephaly [flat spot formed on a baby’s head]
- Severe reduction in bone mass, propensity to fractures, long bone deformities (associated with other genetic syndromes with GJH)
These “patterns of presentation of JH-related musculoskeletal features are highly variable,” so the current thinking is that “they are not directly due to the underlying cause of the JH, but instead as secondary effects mediated by the JH and other factors.” So these characteristics vary a lot from person to person, and therefore are thought to be caused by the hypermobility itself, not by some other factor causing both the hypermobility and the characteristics. It’s more A -> B -> C, rather than A -> B AND A -> C.
Classifying Joint Hypermobility
Joint hypermobility is a well known characteristic of many types of heritable connective tissue disorders (HCTDs), so what does it mean if you have JH?
Directly from the article A Framework for the Classification of Joint Hypermobility and Related Conditions, if you have JH, you fit into one of 3 categories
1. Subjects with asymptomatic, non-syndromic/isolated LJH, PJH, or GJH [or HJH]. Asymptomatic JH may occur in multiple individuals from the same pedigree (i.e. familial asymptomatic JH) and, theoretically, might also occur as an isolated trait in healthy relatives of patients with full-blown* hEDS.
2. Individuals with a well-defined syndrome with JH, also comprising hEDS (i.e., new diagnostic criteria met).
3. In individuals with symptomatic JH but not satisfying the criteria/diagnosis for a syndrome, the term hypermobility spectrum disorder(s) (HSDs) is proposed.
A Framework for the Classification of Joint Hypermobility and Related Conditions
Hypermobility Spectrum Disorders (HSDs)
The following outline and information is summarized and paraphrased from the article A Framework for the Classification of Joint Hypermobility and Related Conditions.
About Hypermobility Spectrum Disorders
- HSDs are exclusion diagnoses, meaning other diagnoses must be ruled out
- HSDs are distinct from hEDS and other syndromes
- Intended as “alternative labels for patients with symptomatic JH who do not have any rare type of EDS and do not meet the criteria for hEDS in terms of severity/pattern of musculoskeletal involvement”
- The “old” Brighton criteria should no longer be used to diagnose patients, but HSDs aren’t meant as a simple substitute
- HSDs are discrete subtypes that fill the gap between asymptomatic JH and hEDS
Types of Hypermobility Spectrum Disorders
- Generalized Hypermobility Spectrum Disorder (G-HSD)
- Generalized joint hypermobility (see GJH above), assessed objectively by, for example, the Beighton criteria
- PLUS one or more secondary musculoskeletal manifestations (see above)
- Pattern and severity of secondary manifestations should be carefully assessed to rule out hEDS
- Most patients with GJH and secondary manifestations who don’t meet hEDS criteria
- Peripheral Hypermobility Spectrum Disorder (P-HSD)
- JH limited to hands and feet (see PJH above)
- PLUS one or more secondary manifestations (see above)
- Localized Hypermobility Spectrum Disorder (L-HSD)
- JH at single joints or groups of joints (see LJH above)
- PLUS one or more secondary manifestations (see above)
- Historical Hypermobility Spectrum Disorder (H-HSD)
- Self-reported (historical) GJH (see HJH above) with negative Beighton score
- PLUS one or more secondary manifestations (see above)
- Important to exclude G-, P-, and L-HSD diagnoses as well as other rheumatologic conditions
Other Important Comments Regarding Hypermobility Spectrum Disorders
The authors of the article A Framework for the Classification of Joint Hypermobility and Related Conditions, make several important comments regarding patients who fall into the HSD category and do not meet the diagnostic criteria for other conditions:
“Many researchers and practitioners with experience on JH and related conditions perceive that the boundaries separating the continuous spectrum of JH-related musculoskeletal manifestations and the true pleiotropic phenotype (i.e. hEDS) are not always straightforward and sometimes arbitrary.“
“While the identification of stricter criteria for hEDS, which more genuinely reflect the original description of the disease, gives more order to the nosology, it leaves out many “non-syndromic” patients who suffer with the various secondary manifestations of JH. These patients do indeed have real medical needs even if they do not meet the criteria for hEDS or another syndrome.“
“In these patients’ category, a limited extension to other organs and tissues, particularly in form of JH-related co-morbidities, is possible, but the overall clinical picture does not fit the criteria for one of the various EDS types.”
“The literature is full of case-control studies showing associations between GJH (usually assessed by the Beighton score) and specific extra-articular disorders. To date, the strongest associations are with anxiety disorders, orthostatic tachycardia, a variety of functional gastrointestinal disorders, and pelvic and bladder dysfunctions. The associations are often real (i.e. easily confirmed by clinical practice) and clinically relevant as these additional manifestations may be commonly encountered in conditions with JH, in particular hEDS, and might impact seriously on the quality of life and management of individuals. Hence, their prompt recognition is useful, and the concurrence with GJH should be emphasized for therapeutic issues.”
“At the moment, it does not seem prudent to consider the combination of GJH and anxiety (or any other strongly associated extra-articular disorders) a syndrome per se, at least from the Medical Genetics perspective… these complications, when encountered in patients belonging to one of the above-mentioned categories of JH, should be defined as JH-related co-morbidities.”
“Asymptomatic JH, HSDs, and hEDS can be brought back to a single continuous spectrum ranging from isolated JH to full-blown* hEDS passing through the various HSDs… The existence of this spectrum is the rationale supporting the dynamic nature of such a classification and the possibility of phenotype transition due to the changing pattern of JH-associated manifestations. The follow-up of these patients may be relevant also for diagnostic accuracy, especially for patients at risk for developing a phenotype consistent with the new criteria for hEDS, but also for those with HSD whose musculoskeletal conditions are resolved by treatment and who therefore in effect revert to having asymptomatic JH.”**
“The nosologic restyling of JH and related conditions is… not intended as a rigid guideline for medical and non-medical professionals, but as an updated framework structured on a wider perspective and on the most recently available data for nurturing more clinical and basic research.”
“Dissecting the molecular basis of hEDS, HSDs, and isolated JH could be one of the future goals of the scientific community, especially in the fields of Human and Medical Genetics. This knowledge will surely ease patients’ classification and prognostication, and, perhaps, will better rationalize medical and economic resources.“
*I’m really not a fan of the expression “full-blown” as a comparison of HSDs to hEDS, but it seems to be popping up in the literature quite often. They have stated very explicitly that the secondary musculoskeletal issues related to JH and the extra-articular disorders that are demonstrably associated with JH and HCDTs can both have a huge impact on the quality of life of someone labeled as having an HSD. I think the expression “full-blown” only serves to undermine the seriousness of the condition, rather than make the distinction between the two conditions, as I assume was the authors’ intention.
As the 2017 diagnostic criteria stand, it is possible for someone to not meet the criteria for hEDS, yet still suffer from many or all of the features described in hEDS but that aren’t part of the diagnostic criteria yet. According to the 2017 article The 2017 International Classification of the Ehlers–Danlos Syndromes,
“These include but are not limited to: sleep disturbance, fatigue, postural orthostatic tachycardia, functional gastrointestinal disorders, dysautonomia, anxiety, and depression. These other systemic manifestations may be more debilitating than the joint symptoms, often impair functionality and quality of life, and should always be determined during clinical encounters.
**I’m also not a fan of the concept of being able to revert from HSD to asymptomatic JH once symptoms have been treated or have become managed. I think the reason they’ve characterized it they way that have is because they haven’t identified the underlying cause for just JH or what makes JH asymptomatic or symptomatic. But I think just because we haven’t been able to identify it, doesn’t necessarily mean an underlying cause doesn’t exist.
But we don’t treat many other chronic diseases in this way. For example, you wouldn’t tell someone with MS that once they are no longer symptomatic (presumably because of treatments) that they no longer have MS. We say that their MS is in remission; a fair characterization of their current status without removing the underlying diagnosis. I think the same terminology and line of thinking would be more appropriate for people with HSDs. That once someone has met the criteria for an HSD, if their symptoms resolve, at least for a time, it would be more accurate to say this person has an HSD that is in remission, rather than say the person person now only has JH.
In fact, the comparison they make in their paper compares the new classification to the classification of arthritis. They write:
“For example, there may be a family history of rheumatoid arthritis (RA) (as defined by accepted international criteria), but the individual presents with some clinical features to suggest autoimmune rheumatic disease but has insufficient clinical and biological markers to define RA. The term “sero-negative inflammatory arthropy” [SNIA] might apply.
“This individual would be managed on the basis of their presenting complaint and followed to determine whether their condition changed in any way that might lead to the diagnosis of RA.
“HSD should be considered in the same way, including the possibility of clinical evolution and transition to another diagnosis (e.g., hEDS).”
In this example, HSD is SNIA and hEDS is RA. As SNIA may change and differentiate itself as RA, or perhaps another form of arthritis, the authors say so may a patient with a HSD’s symptoms change and eventually differentiate it into hEDS, or maybe even another HCTD.
But here the analogy ends because doctors managing the SNIA patient, treating symptom by symptom, would never tell the patient, once symptoms had been resolved, that they no longer had SNIA. Even just typing it, it sounds ridiculous. They still have the condition, but the symptoms are in remission. If the symptoms come back they don’t suddenly have SNIA again while they didn’t before. It sounds equally ridiculous to me to treat HSDs differently. It just isn’t a standard medical practice, and to be taken seriously, I don’t think treating them a different way is going to help.