Youth is full of sport, age’s breath is short; Youth is nimble, age is lame; Youth is hot and bold, age is weak and cold; Youth is wild, and age is tame.
William Shakespeare (1564–1616) ‘Crabbéd Age and Youth’
Participation in youth (i.e. child and adolescent) sports is popular and widespread. Many youngsters train year-round and specialise in their sports in childhood, and during adolescence some may reach peak performance and compete nationally or internationally. It is not uncommon for preteens to train 20 or more hours each week at regional training centres in tennis or gymnastics, to compete in triathlons, or for youngsters as young as 6–8 years of age to play organised hockey or soccer and travel with select teams to compete against other teams of similar calibre. Thus, knowledge about specific physiologic characteristics, management of orthopaedic conditions, injury prevention guidelines, and information regarding non-orthopaedic concerns is imperative to all individuals involved in the healthcare of young athletes.
THE YOUNG ATHLETE IS UNIQUE
Engaging in sports activities at a young age has numerous health benefits, but also involves risk of injury. Indeed, the young athlete may be particularly vulnerable to sport injury due to the physical and physiological processes of growth. Injury risk factors that are unique to the young athlete include specifics of the musculoskeletal system such as an immature skeleton, nonlinearity of growth, maturity-associated variation, the adolescent growth spurt and the response to skeletal injury.1 Young athletes might also be at increased risk because of immature or underdeveloped coordination, skills and perception, in addition to psychological issues. Although problems do not ordinarily arise at normal levels of activity, the more frequent and intense training and competition of young athletes today may create conditions under which this susceptibility exerts itself.
The normal growth pattern is nonlinear; that is, differential growth of the body segments (head, trunk and lower extremities) occurs throughout growth and influences body proportions accordingly.2 At birth, the relative contribution of head and trunk to total stature is highest and declines through childhood into adolescence. Thus, the child is characterised by a proportionally larger head and trunk, and shorter legs compared to an adult. In some events, for example rodeo ‘mutton busting’, one can anticipate that a young ‘top-heavy’ child would be at increased risk of falling off a sheep compared to an older child with proportionally longer legs.
One of the features of the child’s skeleton is the existence of the epiphyseal growth zones (physis). It has traditionally been divided into four zones: the resting or germinal zone, the proliferation zone, the zone of hypertrophy and the zone of enchondral ossification, which is continuous with the metaphysis (Fig. 44.1).
(a) Anatomy of the physis (b) Different parts of the growing bone—the metaphysis, ...