Paediatric Ankle Fractures

Ankle fractures in children aged 15 or younger are very different from ankle fractures seen in adults. This is due to:

  • The presence of soft areas called ‘growth plates’ (or epiphyses). These are found at the end of long bones like the tibia (shin bone) and are crucial for increased length in the bone.
    • Growth plates ‘close’ or solidify into hard bone around the age of 15 for girls and 17–18 for boys. The closure of growth plates is responsible for the height of your child.
    • For more information, see growth plate fractures.
  • Ligaments around the joints tend to be stronger than the soft bone, so that fractures are more likely than ankle sprains.

Ankle fractures in children tend to be classified according to their relation to the growth plate. Interruption to the growth plate can lead to deformity or decreased growth in the affected bone, so classifying fractures by interruption to growth plate is useful in predicting the long-term impacts of the fractures.

Salter Harris types 1 and 2, the most common forms of paediatric ankle fracture, tend to be associated with little growth plate interruption, while types 3, 4 and 5 have higher risks of growth complications.

Special Ankle Fractures in Children

  • Tillaux fracture – this occurs in older children where the growth plate has partially closed. When the ankle and foot are twisted with enough force a small section of bone is pulled away by ligaments between the bones (the talofibular ligaments). If the bone fragment remains in place (undisplaced), this fracture can be treated with a plaster cast. Surgery is required when the bone fragment needs to be pushed back into contact with the tibia (shin bone).
  • Triplane fracture – these occur when the fracture line spreads into two or more directions. These are serious fractures that often need surgery.

Symptoms

A child with a broken ankle is usually in obvious pain and unwilling to walk on it. The signs and symptoms include:

  • Pain around the ankle, often on the inner or outer bony bump
  • Swelling and bruising
  • Refusing to walk, or limping heavily
  • Tenderness when the bone is pressed, rather than the soft tissue in front
  • An ankle that looks out of shape, in more severe fractures

Children rarely sprain an ankle badly. Where a child is tender directly over bone after an injury, a fracture should be assumed until an X-ray says otherwise.

Causes

Most childhood ankle fractures happen during play and sport. The common mechanisms are a twist of the ankle when landing or changing direction, a fall from a height such as playground equipment, and a direct blow.

Because a child’s ligaments are stronger than the growing bone next to them, the force that would sprain an adult ankle tends to break a child’s instead.

Risk Factors

Ankle fractures are more common in children who are active in sport, and in the years just before the growth plates close. Other factors include:

  • Trampolines and playground equipment
  • Contact and cutting sports
  • A previous ankle injury
  • Conditions that weaken bone

Investigations

Your doctor will examine the ankle and check the circulation and feeling in the foot. Tests include:

  • X-ray, the main test, usually taken from at least two directions
  • Comparison X-rays of the other ankle, occasionally used where a growth plate is hard to interpret
  • CT scan, used for fractures involving the joint surface and when surgery is being planned
  • MRI, used where a fracture is suspected but not visible on X-ray

Fractures are described by how they involve the growth plate, because this predicts how the bone will grow afterwards.

Complications

Most childhood ankle fractures heal well. Problems that can follow include:

  • Damage to the growth plate, which can slow or stop growth in part of the bone
  • A bone that grows at an angle, if one side of the growth plate is affected and the other is not
  • A difference in leg length, where growth is affected on one side only
  • Arthritis in later life, where the fracture involved the joint surface
  • Stiffness of the ankle, which usually settles with normal activity

Growth problems are uncommon, but they are the reason children are followed up for longer after an ankle fracture than adults are.

Treatment

Treatment depends on the position of the bones and whether the growth plate and joint surface are involved:

  • Where the bones are in a good position, a cast or a boot for several weeks
  • Where the bones are out of position, they are realigned, usually under an anaesthetic, and then held in a cast
  • Where the fracture cannot be held, or the joint surface is involved, surgery with screws or wires
  • Repeat X-rays during healing, to check the position has not shifted
  • Follow-up over the following months or years, to check that the bone is growing evenly

Metalwork is often removed in children once the fracture has healed. See also sprained ankle and ankle fracture in adults.

Prevention

Most of these injuries happen in ordinary play and cannot be prevented. The risk can be lowered by:

  • Supervision on trampolines, and one child at a time
  • Well-fitting shoes appropriate to the sport
  • Building up sport gradually after a break from it
  • Completing rehabilitation after an ankle injury before returning to sport