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The ability of joints to undergo repeated and rapid movements is attributable to the unique mechanical properties of the extracellular matrix (ECM) of the joint capsule and surrounding ligaments and tendons. A delicate balance exists between ‘stiffness’ and ‘elasticity’ of these tissues. Stiffness comes from very long collagen fibrils that are arranged in elaborate architectures such as parallel bundles in tendon (Fig. 3.1), orthogonal lattices in the cornea and basket-weave in skin, depending on the mechanical requirements of the tissues in which they occur. Elasticity originates from the crimping of collagen fibrils and from elastic fibres in the ECM (Fig. 3.2). These elastic fibres have a unique arrangement of macromolecules that permits extension and contraction at a molecular level. An understanding of the molecular and structural basis of joint hypermobility requires a detailed knowledge of the structure, function and organisation of the collagenous and elastic polymer systems that comprise the ECM.

The first clinical description of articular hypermobility is attributed to Hippocrates, who, in the fourth century B.C., described the Scythians, a race of people inhabiting the region that now forms the Ukraine and Czechoslovakia, as having humidity, flabbiness and atony such that they were unable to use their weapons. Their main problem in warfare was that hyperlaxity of the elbow and shoulder joints prevented them from drawing their bows effectively.

This edition, the fourth in a series spanning some 25 years since the publication of the first edition in 1983, is likely to be the last prepared under the current authorship. In addition to chronicling further progress in the field, it seems appropriate to add a final chapter concerning areas that might be suitable, even ripe, for translational research in the future. This chapter, at times unashamedly speculative, synthesises the ideas of all three authors, each approaching the field from their slightly different perspectives. We apologise to readers if some of our suggestions prove impractical or if we have failed to consider their own areas of particular interest in this wide field.

A common clinical error is to confuse these two terms, which are not synonymous. Hypermobility is defined as an excessive range of joint motion, taking into consideration the age, gender and ethnic origin in otherwise healthy subjects, being greater in males than females, in younger people compared with older people and in those of Asian or African origin compared to those who are Caucasian. It is characterised by an inherent increase in laxity and fragility of the connective tissues. Hypermobility is a direct consequence of ligamentous laxity, which, itself, is an expression of a genetically determined aberration of one or more of the connective tissue fibrous protein genes such as those encoding for collagen(s), fibrillin(s) or tenascin(s)

Adequate methods for measuring the range of movement at joints are essential for the definition of criteria used in the study of clinical problems associated with joint hypermobility. Scoring systems for hypermobility that survey a large number of joints in simple fashion are ideal for epidemiological studies in large populations. Latterly, investigators have devised sophisticated mechanical devices for the precise quantification of movement at a single joint. The greater precision afforded may be ideal for serial assessments in the same patient but this greater precision is of limited use in epidemiological work if the joint fails to mirror the status of laxity at other joints in the body. Moreover, a joint may display acquired hyperlaxity in compensation for a reduced range of movement at adjacent joints, for example in the vertebral column.

Arguably, the most surprising development of the past decade has been the realisation that the effects of JHS do not lie exclusively within the confines of the musculoskeletal system. Nowadays, it is no exaggeration to state that JHS is seen as a multi-facetted multi-system disorder which effectively touches virtually all medical specialties in one way or another.

In an early paper, Sutro (1947) drew attention to the biomechanical aspects of hypermobility. In a study of recurrent effusions in the knees and ankles of American army recruits, he noted an increased range of both active and passive movement in the affected joints. He argued in favour of an “over-length” of certain articular, capsular and ligamentous tissues, and suggested that there might be disproportion in the relative rate of growth of the bones and their attached ligaments.

The heritable hypermobility syndromes are a group of disorders in which joint laxity is a prominent feature. In some of these conditions the loose joints predispose to a wide variety of articular complications and, despite their rarity, they are therefore of considerable rheumatological importance.

The following case histories have been drawn from the records of patients who have attended the Guy’s Hospital Hypermobility Clinic over the past two decades, many of whom have been observed over several years. A striking finding has been the number and variegated pattern of locomotor disorders suffered by individual patients. Many of the disorders encountered were amenable to treatment, and serious disablement was seen in only a few individuals. In each instance the Beighton et al. (1973) mobility scale was used.

Objective. To compare the efficacy of sulfasalazine (SSZ) with its two moieties, 5-aminosalicylic acid (ASA) and sulfapyridine (SP), in patients with active ankylosing spondylitis (AS). Methods. A 26-week randomized, observer-blinded, 2-center, controlled study of treatment with either SSZ, ASA, or SP was conducted in 90 patients with active AS. Patients were evaluated at baseline and at monthly intervals, using several clinical and laboratory measures of disease activity. A global assessment of treatment efficacy was made by both patients and observers at the end of the study period. Results. There were no significant changes in any of the parameters of disease activity in the ASA treatment group. Levels of serum IgG, IgA, and IgM fell significantly during treatment with SP, but none of the other changes reached statistical significance. Plasma viscosity and IgG and IgA levels fell significantly during treatment with SSZ, as did nocturnal spinal pain and overall spinal pain. Patients and observers reported a favorable outcome after treatment with SSZ or SP significantly more often than with ASA treatment. Conclusion. SP appears to be the active moiety in AS, although there was a trend suggesting a better outcome in the SSZ group compared with the SP group, perhaps suggesting the importance of a common sulfonamide structure for efficacy.

A title like that tells where you are going — a relationship as old as Adam and Eve. What gives away the meaning? It's the word heart, that all-purpose metaphor for love and emotion. Hearts have astonishing lives of their own. Hearts are faint and hearts are stout; hearts are open, hearts are closed; hearts are clean and hearts are mean; warm and cold, and faint and bold; hearts are light and hearts are heavy, some as heavy as a stone. They beat as one — two hearts in waltz time. Other hearts are lonely hunters. Hearts are whole . . .

The Ehlers—Danlos syndrome (EDS) is an inherited disorder of connective tissue which is characterised by the clinical triad of articular hypermobility, dermal extensibility and cutaneous scarring. The manifestations are very variable although usually fairly consistent within any kindred, and it has become increasingly evident that EDS is very heterogeneous.