The Young Athlete
Injury risk factors unique to the young athlete
There are a number of factors that put young athletes at greater risk of being injured which need to be considered when deciding on the type of sport to be practiced, the duration of training sessions, the matching of athletes in competition and the rate at which training/competition is progressed.
Nonlinearity of growth
Growth is nonlinear i.e. the various body segments such as head, trunk and limbs do not grow at the same rate and this impacts on body proportion and balance. In early development, the head and trunk contribute more to total stature but this declines through childhood into adolescence since the limbs now grow at a greater rate than the trunk. In long bones such as the femur (thigh), tibia (shin) and humerus (upper arm) there are growth plates (epiphyseal). These are the zones in which the majority of the growth or lengthening of the bone occurs. The contribution to growth of these growth plates is not the same i.e. where a long bone has growth plates at both ends, growth may not occur at the same rate at both ends. In the humerus (upper arm) the proximal growth plate (the one nearer the shoulder) contributes more to growth while in the femur (thigh) it is the distal growth plate (the one nearer the ankle).
Fig.1 View of the side of the knee showing the epiphysis (head), metaphysis (neck), diaphysis (shaft) and growth plates
In general, girls mature faster than boys do at any given age. Boys that mature early will have performance and functional advantages over those who mature late and this will influence the choice of sport and the injury risk. Chronological age will impact on injury risk since for any given age there may be marked difference between the children. A child who is 12 years and 10 months old might be significantly heavier, taller and stronger than a child who is 12 years and 1 month yet both could be entered into a competition category “12 years”. This leads to unbalanced competition between late/early maturers and older/younger boys and increases the likelihood of injuries in contact sports.
The adolescent growth spurt
Structural changes occur in the growth plate cartilages resulting in them becoming thicker and more fragile which increases the risk of injury (Alexander CJ. Effect of growth rate on the strength of the growth plate-shaft junction. Skel Radiol 1976;1(2):67–76). Studies have shown that the incidence of growth plate fractures increase during pubescence (Bailey DA, Wedge JH, McCulloch RG et al. Epidemiology of fractures of the distal end of the radius in children as associated with growth. J Bone Joint Surg Am 1989;71(8):1225–31). Some authorities propose that the adolescent growth spurt increases the risk of growth plate injuries by increasing the muscle-tendon tightness and thereby reducing flexibility, but there is little evidence to support this.
The response to skeletal injury
While the mechanism of injury in young and adult athletes might be the same, the injuries sustained are quite different because of the difference in the structure of their bones.
- The periosteum that lines bones is thicker in children and can heal better.
- The cartilage at the end of bones is thicker in children and can heal faster.
- The epiphyseal growth plates in children are vulnerable to disruption.
- The tendon and ligament attachment sites in children are cartilaginous and are therefore vulnerable to injury.
- The cortex (outer shell) of bones in children is more elastic and therefore less likely to fracture fully.
- During growth spurts, the growth plates become thicker, predisposing to greater risk of injury.
Table 1. Comparison of injuries that occur with similar mechanisms in children and adults
|Site||Mechanism||Injury in adult||Injury in child|
|Distal IPJ of finger||Hyperflexion||Mallet finger||Salter-Harris type II or III fracture of distal phalangeal epiphysis|
|Hand||Punching||Fracture of MCP head||Salter-Harris type II of metacarpal epiphysis|
|Shoulder||Fall on point of shoulder||AC joint sprain||Fractue of middle third of clavicle epiphysis|
|Thigh/hip||Acute flexor/extensor strain||Quad/hamstring strain||Apophyseal avulsion of AIIS or ischial tuberosity|
|Knee||Overuse||Patellar tendinopathy||Osgood-Schlatter or Sinding-Larsen-Johansson|
|Ankle||Acute inversion||Lateral ligament sprain||Salter-Harris type I or II fracture of tibia or fibula|
|Heel||Overuse||Achilles tendinopathy||Sever’s disease|
Fig. 3 The Salter-Harris classification of growth plate fractures
Immature or underdeveloped coordination, skills and perception are also risk factors for developing injuries in the young athlete since this affects intermuscular coordination, proprioception and the ability to carry out skills in a manner that is both safe and effective.
Common paediatric athletic injuries include:
- acute fractures
- shoulder pain
- elbow pain
- wrist pain
- back pain
- hip pain
- knee pain
- foot pain
Young athletes are more likely to incur an avulsion fracture than to strain a muscle or sprain a ligament, common injuries in the adult athlete. Avulsion fractures occur at the site of the apophyseal attachment i.e. where large tendons attach to bones and to a lesser extent, where ligaments attach to bone. They are characterised by a fragment of bone being pulled from the rest of the bone while still being attached to the tendon/ligament. Common sites include:
- sartorius – ASIS
- rectus femoris – ASIS
- hamstrings – ischial tuberosity
- ilipsoas – lesser trochanter of femur
- gluteus medius – greater trochanter of femur
- anterior cruciate ligament – tibial plateau
- patellar tendon – tibial tubercle
- peroneus brevis – base of 5th metatarsal
- triceps brachii – olecranon process
- forearm flexors – medial epicondyle of humerus