Dynamic knee stability during childhood: Mark De Ste Croix and Martine Deighan
Participation in sport and exercise places the participant at an increased risk of injury, independent of age and sex. This, of course, includes the period of childhood, and it has been proposed that children may be at a greater risk than adults due to developing musculoskeletal systems (see Chapter 1) that may not be considered fully mature (Funasaki 2009). Collard et al. (2009) suggest that all forms of physical activity place the child at greater risk of injury than sedentary individuals due to a high level of exposure to situations where muscles and joints are placed under stress. Due to the high prevalence of physical activity-and sportrelated injuries, and the associated negative short-and long-term consequences, prevention of these injuries in children is important. With an estimated 45 million children involved in organized sports in the United States alone, it is hardly surprising that sport contributes to the major risk of injury during childhood, estimated in the USA to be about 3 million per year (Fecteau et al. 2008; Veigel and Pleacher 2008). These injuries influence health and fitness and have a socioeconomic impact, but most of them can be prevented. There are a number of well-recognized paediatric conditions associated with the mechanical stresses placed on joints, tendons and ligaments during sporting activities. These include osteochondral injury of the elbow joint, Sever’s disease of the ankle, avulsion fracture of the pelvis and Osgood-Schlatter disease (Funasaki 2009). Some of these injuries may lead to joint dysfunction such as deformity, pain and limited range of motion. Although some of these conditions may progress into adulthood, early detection can lead to complete recovery without complications. More importantly, a clear understanding of the possible causes of such injuries means that prevention can be put in place during childhood to avoid such consequences. It is beyond the scope of this chapter to explore all of these paediatric conditions, and therefore the focus of this chapter is on dynamic knee stability, which is important in preventing non-contact anterior cruciate ligament (ACL) injury. Dynamic knee stability is also mostly influenced by muscular, neuromuscular, hormonal and biomechanical factors. The incidence, severity, costliness and long-term consequences from ACL tears make prevention a high priority in the medical and research communities (Bonci 1999). There is good evidence that
ACL injury at a young age increases the relative likelihood of suffering from osteoarthritis in older age (Palmieri-Smith and Thomas 2009). The focus of this chapter is to explore the role that dynamic stability of the knee plays in reducing the relative risk of injury from a muscular and neuromuscular perspective.