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Hypermobility | |
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Other names | hyperlaxity, benign joints hypermobility syndrome (BJHS), hypermobility syndrome (HMS) [1] |
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Hypermobile fingers and thumb | |
Specialty | Rheumatology, Medical genetics |
Hypermobility, also known as double-jointedness, describes joints that stretch farther than normal. [2] For example, some hypermobile people can bend their thumbs backwards to their wrists, bend their knee joints backwards, put their leg behind the head, or perform other contortionist "tricks". It can affect one or more joints throughout the body.
Hypermobile joints are common and occur in about 10 to 25% of the population. [3] Most have no other issues. In a minority of people, pain and other symptoms are present. This may be a sign of hypermobility spectrum disorder (HSD). In some cases, hypermobile joints are a feature of connective tissue disorders. One of these, Ehlers-Danlos Syndrome, was classified into several types which have been found to be genetic. Hypermobile Ehlers–Danlos syndrome (hEDS), formerly called EDS Type 3, remains the only EDS variant without a diagnostic DNA test.
In 2016 the diagnostic criteria for hEDS were re-written to be more restrictive, with the intent of narrowing the pool of hEDS patients, in the hope of making it easier to identify a common genetic mutation and create a diagnostic DNA test.
At the same time, joint hypermobility syndrome was renamed as hypermobility spectrum disorder, and redefined as a hypermobility disorder that does not meet the diagnostic criteria for any heritable Connective Tissue Disorder (such as hEDS, other types of Ehlers–Danlos Syndrome, Marfan Syndrome, Loeys–Dietz Syndrome, or osteogenesis imperfecta). Sometimes called "non-genetic EDS," hypermobility spectrum disorder can have the same signs as hEDS, but be caused not by a heritable genetic mutation but by problems in fetal development, such as pre-natal exposure to toxins like agricultural chemicals, drugs, or alcohol. Fetal Alcohol Spectrum Disorders affect at least 1 in 20 people in the U.S., [4] and joint hypermobility with other symptoms is common. [5]
People with joint hypermobility syndromes may develop conditions caused by their unstable joints. [6] [7] These conditions include:
Joint hypermobility may be associated with other conditions. These include ADHD, autism, dyspraxia, fibromyalgia, hereditary connective tissue disorders, mitral valve prolapse, and anxiety disorders such as panic disorder. [9] [10] [11] [3] [12] Joint hypermobility does not cause these other conditions. Most people with joint hypermobility do not have them. In people who do, the underlying cause can be a general syndrome that affects the whole body and brain (such as Autism or Fetal Alcohol Spectrum Disorders), or a genetic condition or disease that affects certain tissues (such as Ehlers-Danlos syndrome or lupus).
Medical conditions that can cause joint hypermobility include FASDs, Stickler syndrome, Ehlers–Danlos syndrome, [13] Marfan syndrome, [13] Loeys–Dietz syndrome, rheumatoid arthritis, osteogenesis imperfecta, [13] lupus, polio, Fragile X syndrome, Down syndrome, [13] Morquio syndrome, cleidocranial dysostosis and myotonia congenita. All have other diagnostic criteria as well.
Hypermobility generally results from one or more of the following:
Any of these causes can increase the level of mechanical stress on a joint. Chronically stressed joints may experience higher or faster than usual levels of wear, leading to osteoarthritis.
Hypermobility tends to run in families, suggesting a genetic basis for at least some forms. The term double jointed is often used to describe hypermobility; however, the name is a misnomer and should not be taken literally, as people with hypermobile joints do not have any extra joints, or any extra bones or parts in the joint.
Most people with hypermobile joints do not have a hypermobility spectrum disorder. Approximately 5% of the healthy population has one or more hypermobile joints. However, people with symptomatic hypermobility are subject to many difficulties. For example, their joints may be easily injured, be more prone to complete or partial dislocation due to the weakly stabilized joint, and they may develop problems from muscle fatigue (as muscles must work harder to compensate for weakness in the ligaments that support the joints). Hypermobility syndromes can lead to chronic pain or even disability in severe cases.
Hypermobility has been associated with myalgic encephalomyelitis (chronic fatigue syndrome) and fibromyalgia. Hypermobility syndromes can cause physical trauma, pain, and stress (in the form of joint dislocations, joint subluxations, joint instability, sprains, etc.), and chronic stress from repeated trauma is a possible trigger for chronic conditions such as fibromyalgia. [14]
Symptoms are often exacerbated during pregnancy. During pregnancy, the body releases relaxin and certain hormones that alter ligament physiology, easing the stretching needed to accommodate fetal growth as well as the birthing process. [15] The combination of hypermobility and pregnancy-related pelvic girdle during pregnancy can be debilitating. The pregnant person with hypermobile joints may be in significant pain as muscles and joints adapt to the pregnancy. Pain makes standing or walking difficult during pregnancy, so some women who have one of these disorders find they need to use a wheelchair during pregnancy. [15] They are also at risk for excessive bleeding during and after childbirth, and the baby is at risk of dislocated joints, especially of the clavicle, hip, and neck. [15]
Hypermobility syndrome is generally considered to comprise hypermobility together with other symptoms, such as myalgia and arthralgia. It is relatively common among children and reported more often in females than males.
Current thinking suggests four causative factors:
Hypermobility can also be caused by genetic or developmental disorders that reduce the strength of the connective tissue the body can make. Commonly, hypermobility is dismissed by medical professionals as nonsignificant, though it may be a sign of a systemic problem. [17]
Joint hypermobility is often correlated with hypermobile Ehlers–Danlos syndrome (hEDS, known also by EDS type III or Ehlers–Danlos syndrome hypermobility type (EDS-HT)). Ehlers–Danlos syndrome is a genetic disorder caused by mutations or hereditary genes, but the genetic defect that produced hEDS is largely unknown. In conjunction with joint hypermobility, a common symptom for hEDS is smooth, velvety, and stretchy skin. When diagnosing hEDS, the Beighton Criteria are used, but are not always able to distinguish between joint hypermobility syndrome and hEDS. [18]
Ehlers–Danlos hypermobility type can have severe musculoskeletal effects, including:
Joint hypermobility syndrome shares symptoms with other conditions such as Marfan syndrome, Ehlers-Danlos Syndrome, and osteogenesis imperfecta. Experts in connective tissue disorders formally agreed that severe forms of Hypermobility Syndrome and mild forms of Ehlers-Danlos Syndrome Hypermobility Type are the same disorder.[ citation needed ] The basic issue is that Ehlers-Danlos Syndrome was defined based on its observable symptoms in the skin and joints, but is now classified as a genetic disorder. However, it is impossible to tell whether a person has EDS symptoms due to an inherited EDS gene, a spontaneous mutation that causes identical symptoms, or a problem in fetal development causes identical symptoms, without both knowing the genetic family history and performing a specialized genetic test. The results do not matter to clinical treatment of the symptoms.
Generalized hypermobility is a common feature in hereditary connective tissue disorders and many features overlap, but often features are present that enable differentiating these disorders. [19] The inheritance pattern of Ehlers-Danlos syndrome varies by type. The arthrochalasia, classic, hypermobility and vascular forms usually have an autosomal dominant pattern of inheritance. Autosomal dominant inheritance occurs when one copy of a gene in each cell is sufficient to cause a disorder. In some cases, an affected person inherits the mutation from one affected parent. Other cases result from new (sporadic) gene mutations. Such cases can occur in people with no history of the disorder in their family.
The dermatosparaxis and kyphoscoliosis types of EDS and some cases of the classic and hypermobility forms, are inherited in an autosomal recessive pattern. In autosomal recessive inheritance, two copies of the gene in each cell are altered. Most often, both parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.
As of July 2000, hypermobility was diagnosed using the Beighton criteria. In 2017, the criteria changed, but still involve the Beighton score. [21] The Beighton criteria do not replace the Beighton score but instead use the previous score in conjunction with other symptoms and criteria. HMS is diagnosed in the presence of either two major criteria, one major and two minor criteria, or four minor criteria. The criteria are:
The Beighton score is an edited version of the Carter/Wilkinson scoring system which was used for many years as an indicator of widespread hyper-mobility. Medical professionals varied in their interpretations of the results; some accepting as low as 1/9 and some 4/9 as a diagnosis of HMS. Therefore, it was incorporated, with clearer guidelines, into the Beighton Criteria. The Beighton score is measured by adding 1 point for each of the following:
The Beighton score has been widely used among athletes for screening purposes. It does not appear to be a valid scale when used for this purpose: there exists a statistically significant correlation between the score and the athlete's passive shoulder and hip ranges of motion, but the difference is small enough to be buried by measurement error. [22]
It is important that hypermobile individuals remain fit – even more so than the average individual – to prevent recurrent injuries. Regular exercise and exercise that is supervised by a physician and physical therapist can reduce symptoms because strong muscles increase dynamic joint stability. Low-impact exercise such as closed kinetic chain exercises are usually recommended as they are less likely to cause injury when compared to high-impact exercise or contact sports. [23]
Heat and cold treatment can help temporarily to relieve the pain of aching joints and muscles but does not address the underlying problems.
Medication is not the primary treatment for hypermobility, but can be used as an adjunct treatment for related joint pain. Nonsteroidal anti-inflammatory drugs are the primary medications of choice. Narcotics are not recommended for primary or long-term treatment and are reserved for short-term use after acute injury.
For some people with hypermobility, lifestyle changes decrease symptom severity. In general, activity that increases pain is to be avoided. For example:
Hypermobile joints occur in about 10 to 25% of the population, but do not define hypermobility syndromes. [3]
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