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A 35-year-old member asked:

I'm wondering why are people born double jointed?

1 doctor answer1 doctor weighed in
Dr. Laurence Badgley
General Practice 53 years experience
JHS: Medical name is joint hypermobility syndrome. This is mostly inherited in female line & women can lock knees & touch palms to floor, oppose thumb to forearm, & put feet behind neck as children. Imo is conserved trait to impart ease of childbirth & by 4th childbirth often takes minutes not hours & more infants born healthier. Condition also highly associated with development of fibromyalgia.
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Dr. Laurence Badgley
General Practice 55 years experience
Provided original answer
The unifying genetic relationship in fibromyalgia is probably Joint Hypermobility Syndrome (JHS), a known genetic condition.  I have noted that a good portion of female fibromyalgia sufferers satisfy the Bristol Criteria for JHS, and are able to oppose thumb to lateral radial skin, hyperextended elbows and knees, and can place their palms on the floor with knees locked.  Most could put their feet behind their head and back bridge as youngsters and many can do so as adults.  JHS is a disorder with a spectrum of penetrance; with Marfans and Ehlers-Danlos at the clinical severity end of the spectrum.  My speculation is that the trait is conserved in females because it increases pelvic joint (SIJ and symphysis pubis) flexibility during childbirth.  Many of my patients with fibromyalgia and subclinical JHS delivered their fourth or fifth child in minutes rather than hours.  I speculate that repetitive childbirth, in conjunction with the hormone Relaxin, progressively loosens pelvic ligaments.  This functionality would seem to favor infant survivability.  To my mind fibromyalgia results from the effects of a loose ligament-skeletal system attempting to maintain a medial center of gravity via chronic muscle spasm leading to widespread ischemic trigger points (after the work of Shah at NIH).
Jul 1, 2013
Dr. Laurence Badgley
General Practice 55 years experience
Provided original answer
A doctor at Heathtap.com, a Rheumatologist, commented that he has, "found no increased incidence of hypermobility in my scores of patients with FM".  His comment is not atypical.  In 1999, a study in England revealed that amongst Rheumatology referrals only  4.67% of persons with the joint hypermobility phenotype were being recognized, despite criteria for evaluating JHS.  A study reviewer stated, "hypermobility is under-medicalized!" (British Society of Rheumatology  members' Hypermobility Syndrome perception survey,  1999 [Grahame R, Bird H.  Rheumatology 40 (5): 559-69, 2001].  As early as 1966, it was stated, "another view is that isolated ligamentous laxity is a mild mesenchymal developmental disorder which lies at one end of a spectrum of heredofamilial connective issue disease with a fully-developed picture of Marfan's and Ehlers-Danlos at the other (Kirk JA, Ansell BM, and Bymster EG.  Ann Rheum Diseases 1967 26: 419-425. In 1993, a study tested an hypothesis that joint hypermobility is participant in the pain of fibromyalgia.  338 children between 9 and  15 were evaluated with findings that 13% had joint hypermobility and 6% had fibromyalgia per ACR criteria.  81% of the children with fibromyalgia had joint hypermobility.  40% of the children with joint hypermobility had fibromyalgia.  One conclusion was, "the study suggests that there is a strong association between joint hypermobility and fibromyalgia in school children (Buskila et al.  Joint Hypermobility in School Children.  Annals of Rheumatic Diseases.  Vol: 11, No. 1, pp39-42).  In 1998, a study in Spain compared 66 women with fibromyalgia to 70 women with other Rheumatologic  diseases.  The study found that 27% of women with fibromyalgia had joint hypermobility compared to 11.4 % of women with other Rheumatologic disorders (Acasuso-Diaz and Collantes-Estevez.  Joint Hypermobility in Paients with Fibomyalgia.  Arthritis  Care and Research,  Vol: 11, ( FitzCharles opined, in 2000, "there is increasing evidence that at least a sub-group of patients with soft tissue musculoskeletal pain, widespread pain, or fibromyalgia are hypermobile.  Clearly, hypermobility is not the only or the major factor in the development of widespread pain or fibromyalgia, but rather a contributing mechanism in some individuals" (FitzCharles M.  Is Hypermobility a Factor in Fibromyalgia?"  Journal of Rheumatology, Vol: 27. no.7, pp 1587-1589, 2000. A book devoted to the subject was published (Elsevier in 2010).  "Hypermobility, Fibromyalgia, and Chronic Pai n", edited by Professor Rodney Grahame; past editor of "Rheumatology", and held presidency of British Society for Rheumatology.   Somewhere in the midst of practicing medicine for 48 years, I discovered a truism about the practice of medicine follows:  "within the practice of medicine what is not looked for is rarely seen".
Jul 25, 2013

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A 18-year-old female asked:

How are people double-jointed?

2 doctor answers6 doctors weighed in
Dr. Thomas Dowling
Orthopedic Spine Surgery 42 years experience
They do not have a : Double joint but are just more flexible which can be for a variety of reasons including some syndromes or just related to their genetic makeup or related to activities like gymnastic, dance or yoga done regularly.
Created for people with ongoing healthcare needs but benefits everyone.

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Last updated Jul 25, 2013

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