In 1967, Kirk and colleagues first used the term hypermobility syndrome.1 They described generalized joint laxity causing symptoms in an otherwise normal subject. Hypermobility syndrome is a commonly unrecognized cause of focal or diffuse musculoskeletal problems.2 Joint hypermobility syndrome (JHS) belongs to a group of rare hereditary disorders of the connective tissues, along with Ehlers–Danlos syndrome, Marfan syndrome and osteogenesis imperfecta. Morbidity from JHS may be the result of musculoskeletal, skin, ocular or visceral involvement and death can occur from acute vascular collapse; however, JHS is not progressive, destructive or disabling.237
The epidemiology of JHS has not been frequently studied in Middle Eastern populations; therefore, the prevalence of JHS in a cohort of young, apparently healthy, Omani men and women was determined in this study.
Patients and methods
From 1 March to 1 April 2007 at the Sohar Regional Hospital in Sohar, Oman, native men and women aged 16–45 years, who were visiting family members in the hospital, were randomly invited to participate in the study and informed consent was obtained. Expatriates were excluded from the study. Study subjects were interviewed for history of musculoskeletal pain and joint stiffness, occupation and family history of hypermobility in first-degree relatives. Targeted musculoskeletal examination was carried out by a single observer to detect joint hypermobility using Beighton's scoring system, which consists of the following five criteria: (1) passive apposition of thumb-to-flexor aspect of forearm, (2) passive hyperextension of the fifth metacarpophalangeal joint beyond 90 degrees, (3) hyperextension of the elbow joint beyond 10 degrees, (4) hyperextension of the knee joint beyond 10 degrees and (5) ability to place palms on floor without bending the knees. Criteria 1–4 received a score of 1 point for either side of the body involved and criterion 5 received a score of 1 point, thus bringing the maximum possible score to 9.
Joint hypermobility was diagnosed if Beighton's score was ≥ 5 and benign JHS was defined according to the modified diagnostic criteria shown below. JHS was diagnosed by the presence of two major criteria, one major plus two minor criteria or four minor criteria. The first major and minor criteria were mutually exclusive, as were the second major and minor criteria.
A Beighton score of 1, 2 or 3 out of 9.
Arthralgia in one to three joints or back pain for more than 3 months, spondylosis/spondylolisthesis.
Dislocation/subluxation in more than one joint or in one joint on more than one occasion.
Soft tissue rheumatism in more than three lesions (e.g. epicondylitis, tenosynovitis, bursitis).
Marfanoid habitus [e.g. tall, slim, span-to-height ratio > 1.03, upper-to-lower segment ratio < 0.89, arachnodactyly (with positive Steinberg/wrist signs)].
Abnormal skin: striae, hyperextensibility, thin skin, papyraceous scarring.
Eye signs: drooping eyelids, myopia or antimongoloid slant.
Varicose veins, hernia or uterine/rectal prolapse.
Ethical approval for this study was granted by the Oman Medical College/West Virginia University Institutional Review Board (IRB). Statistical analysis of data used two-way analysis of variance with unweighted means analysis.
A total of 222 subjects were studied and the demographic and anthropometric features of the study population are shown in Table 1. Women had a higher mean age (P < 0.001) and body mass index (BMI) (P < 0.05) than men. Joint hypermobility was detected in 14 (6.3%) subjects (8% of women and 4.5% of men). The mean age of women with joint hypermobility was 34 years (range 23–45 years), compared with 26 years (range 17–35 years) for men, and the mean age of women and men without joint hypermobility was 30 and 24 years, respectively. Subjects with joint hypermobility had a mean Beighton score of 4, compared with a mean score of 1 in individuals without joint hypermobility. Among men, Beighton scores of 4–9 and 1–3 were seen in 3% and 38%, respectively; for women, corresponding scores were 4% and 53%, respectively. Subjects who met the criteria for joint hypermobility also had other features of joint laxity (Table 2); many subjects had hypermobility of the little fingers (64%), hips (7%), knees (29%), elbows (29%) and thumbs (43%).
AS, antimongoloid slant; BS, Beighton score; H, hernia; JD, joint dislocation; LL, lid laxity; M, myopia; RP, rectal prolapse; S, striae; S/H, span-to-height ratio; SH, skin hyperextensibility; TN, thumb sign; TS, thin skin; U/L, upper-to-lower segment ratio; UP, uterine prolapse; VV, varicose Veins; WS, wrist sign.
Among subjects with hypermobility, three men and six women had chronic lower back pain, one man and four women had chronic knee pain and one woman had chronic ankle pain. Seven subjects with joint hypermobility (50%) reported a family history of musculoskeletal complaints in at least one first-degree relative. Table 3 details individual musculoskeletal characteristics of JHS in our Omani cohort. A total of 86% (12 out of 14) of subjects with joint hypermobility had one or more features of Marfanoid habitus, although lid laxity, thin skin, skin hyperextensibility and rectal prolapse were not observed in any subject.
The hypermobility syndrome refers to a constellation of musculoskeletal symptoms and clinical findings of diffuse joint laxity in an otherwise normal individual.2 When not associated with musculoskeletal symptoms, the physical findings are best termed diffuse joint hypermobility. This condition is usually recognized at between 30 and 40 years of age. Signs and symptoms as a result of hypermobility may be generalized or localized111 and morbidity may include frequent ankle pains, knee effusions, chondromalacia patellae, dislocations of the shoulders and recurrent episodes of back and joint pain.291213
It is believed that certain genes responsible for the production of collagen are predisposed to the development of hypermobility.414 Generalized joint laxity is commonly seen in healthy individuals who do not have health complaints and hypermobility that is not associated with systemic disease occurs in fewer than 2–13% of the US population.6715 Joint hypermobility scores of > 5 were found in fewer than 2% of randomly selected adults,7 although there may be a high prevalence of joint hypermobility among certain populations, such as ballet dancers, gymnasts, circus contortionists, and musicians.9111619 Age, sex and ethnicity all appear to have an influence on hypermobility29152022 and the prevalence of symptomatic joint hypermobility is typically higher in women than in men (5% vs. 0.6%, respectively).523 Younger people are more hypermobile than older individuals1,1116 and the prevalence of increased joint laxity varies among different ethnic groups, e.g. Asians are at a higher risk than Africans and both have a higher frequency of hypermobility syndrome than Caucasians.11152021
This is one of only a few prevalence studies of JHS among the Omani population and we documented features of the syndrome in 6.3% of Omani adults aged 16–45 years (thus, the prevalence of JHS is 630 in 10 000) and the prevalence of hypermobility among women was almost twice that of Omani men. In contrast, related inherited disorders of connective tissue such as Ehlers–Danlos syndrome, Marfan's syndrome and osteogenesis imperfecta have an estimated prevalence of 1 in 10 000 to 1 in 25 000, 2 to 3 in 10 000 and 1 in 12 000 persons, respectively.2426 Ehlers–Danlos syndrome has no ethnic predisposition,24 while Marfan's syndrome also occurs worldwide with no predilection for either sex.25
In a house-to-house population survey in Muscat, Oman, Pountain27 questioned and examined 920 adults about musculoskeletal pain to confirm its relationship to joint mobility and BMI.27 Joint mobility scores were higher in women than in men and, at all nine criteria sites included in the Beighton score, laxity was significantly more common in women than men. Among Omani women aged 19–28 years surveyed for hypermobility, the prevalence of JHS was 29%, with higher scores noted among those who often complained of pain. The scores declined with age and were higher than those reported in Europeans and similar to those in Africans and Indians. Extreme joint laxity (Beighton score 7–9) was seen only in females and was associated with increased symptoms in those aged 16–25 years. BMI was higher in females with back or knee pain than in those without such pain. In males, only knee pain was associated with higher BMI. More recently, Clark and Simmonds observed that 21% of Omani women attending a hospital-based physiotherapy practice suffered from JHS.28
The present study also documents the rather high frequency of Marfanoid features, typically seen with greater frequency among men, in the Omani population. A span-to-height ratio of > 1.03 in 15% of men and 13% of women seemed reasonable to the authors of the present study. However, an upper-to-lower segment ratio of < 0.89 in more than one-third of the women was not an expected finding.
Other diverse signs and symptoms in JHS include impaired proprioception acuity,2930 orthostatic symptoms (e.g. orthostatic hypotension, syncope, presyncope, palpitations, chest discomfort, fatigue, heat intolerance), which may occur noted in 78% of individuals,31 varicose veins,32 articular and cutaneous laxity,33 and mitral valve34 and pelvic organ prolapse.35 Many of these features can also be seen in collagen-related diseases such as osteogenesis imperfecta (Type 1 defect) and Ehlers–Danlos syndrome (Types I, III and V) with resultant abnormalities in blood vessels and articular ligaments; however, collagen types are not altered in individuals with JHS.3638 Hypermobile individuals are more likely to complain of diffuse pain syndromes such as fibromyalgia.3841 JHS presents with a wider range of overlapping features than other connective tissue disorders, although these occur less commonly. The degree of hypermobility, although extensive in JHS, is less spectacular than in some of the forms of Ehlers–Danlos syndrome and skin stretchiness and poor scar formation are less extreme in JHS than in connective tissue disorders. Patients with connective tissue defects are more susceptible to the effects of trauma and overuse. Soft tissue injury and fractures due to stress occur with higher frequency in those with JHS than in those without.10
In the light of its high prevalence, JHS has special importance among the hereditable disorders of connective tissue; however, is the most likely to be overlooked and to go undetected. Doctors and other health care providers are trained to examine for reduction of joint mobility rather than for an increased range; therefore, hypermobility is commonly missed on physical examination. Furthermore, the absence of laboratory abnormalities makes the diagnosis of JHS problematic and there are no agreed physical criteria for a finding of hypermobility, merely a rather crude set of diagnostic manoeuvres which have come to be known as the Beighton's criteria.11 Beighton's method is quick and simple to perform and uses an arbitrary score of ≥ 4 as a cut-off for hypermobility. It remains the most commonly used diagnostic tool in clinical and epidemiological studies and has been incorporated, with minor modifications only, into the new proposed criteria for JHS.42
A limitation of this study was that although we identified a high percentage of Marfanoid features among subjects with joint hypermobility, we were unable to perform echocardiograms to look for aortic root pathology. Thus, we could not determine an accurate estimation of the prevalence of Marfan syndrome.
In conclusion, JHS, with associated Marfanoid features, appears to be a frequently unrecognized cause of musculoskeletal problems in Oman and may be almost twice as common in women than men.