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

 

Maturity-associated variations

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.

Fig 2. Contrasting features of growing bone (left) and adult bone (right)

 

  • 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:

 

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

 

HHH Young Athletes