Articular mobility in an African population.

There is considerable variation in the range ofmovements which are possible in the joints of normal individuals. In general, females are more mobile than males, while joint laxity decreases with age (Ellis and Bundick, 1956; Wynne-Davies, 1971). Ethnic differences in joint mobility have also been described. For instance, Negroes and Indians have been shown to have a greater range of movements than Caucasians of the same age and sex (Harris and Joseph, 1949). Similarly, in an investigation in Cape Town, Indians were found to be more loose-jointed than indigenous Xhosa and Hlubi, who in turn had a greater degree of joint laxity than white South Africans (Schweitzer, 1970). Articular mobility is a graded trait and at one end of the spectrum a considerable degree of joint laxity may occur in normal individuals (Wood, 1971). Apart from this form of hypermobility, joint laxity is also a component of a variety of genetically determined syndromes (McKusick, 1966; Beighton, 1970). It can also occur in the absence of other stigmata as a simple inherited entity (Sturkie, 1941; Carter and Sweetnam, 1958, 1960; Beighton and Horan, 1970). It has been suggested that hypermobile individuals are prone to orthopaedic disorders, such as degenerative joint disease, dislocations, joint effusions, and muscular pains (Hass and Hass, 1958; Kirk, Ansell, and Bywaters, 1967; Grahame, 1971). Articular laxity has also been implicated as an important factor in the genesis of congenital dislocation of the hip (Wynne-Davies, 1970). For these reasons, hypermobility may well be of considerable clinical significance. An epidemiological survey has recently been completed among the Tswana people of the Western Transvaal. The main aims of this investigation were the study of various bone and joint conditions, but the survey also provided an excellent opportunity for the measurement of the range ofjoint movements in a large number of individuals and for the assessment of the influence of age, sex, and somatotype on their articular mobility. The importance of joint laxity in the production of non-specific musculo-skeletal complaints was also evaluated. The purpose of this paper is to present the results of this investigation and to discuss the clinical significance of the observations which were made.