Joint hyperlaxity and its long-term effects on joints.

The range of movement at a joint varies between individuals. Reasons for this include inherited collagen structure in the joint capsule and ligaments, inherited shape of the bony articulating surfaces and neuromuscular tone which may be acquired and is modified by training. Methods for quantifying the range of movement at joints are described and compared, including the hyperextensometer and the Carter and Wilkinson score. Clinical patterns of joint hyperlaxity and their correlation with aetiology are discussed. Joint hyperlaxity may be advantageous in certain sports. Coaches need to be aware of optimum methods for improving it as well as for guarding against injury. Conversely, physiotherapists may learn from sports physiologists in the management of symptoms arising from patients who have hyperlax joints. Joint stability reduces the risk of injury. Joint hyperlaxity may also be associated with premature osteoarthritis but this is not always so. Joint instability may be the most potent cause though a radiological survey of retired teachers of physical education conducted by our Unit failed to show a higher incidence of osteoarthritis after a life spent in sport than in sedentary controls. However, certain factors that place some individuals at particular risk were identified.