One of the biggest concerns for children with ankle fractures is the risk of damage to the growth plate called physeal arrest. Surgeons evaluating children with physeal fractures of the lower leg bones (tibia and fibula) must be very careful to identify the specific type of fracture and all other areas that might also be injured (e.g., soft tissues such as cartilage, tendons, ligaments).
Successful treatment depends on an accurate diagnosis. Placing a child in a leg cast when there is a large gap in the bone can result in pain and failure to heal. A swollen muscle trapped between the bone and another anatomic part or a piece of flap of bone jammed in the fracture space must be surgically removed before fracture healing can occur.
The clinical exam begins with an understanding of the injury mechanism (e.g., twisting, blunt force). Inspection and palpation are important ways to assess the damage. Not all fractures show up on X-rays so the exam can be the most valuable tool in diagnosing the problem. Swelling may put pressure on the local blood vessels and nerves causing additional symptoms. A special tool called a Doppler can be used to test arteries for adequate blood flow.
X-rays and CT scans will be ordered. Joint spaces, bone alignment, damage to the physeal plate, and bone gapping may be revealed. Any young child with what seems like an “ankle sprain” must be checked for fractures. In young children, the skeletally immature ankle is more cartilage, soft tissue, and ligament than bone. The physeal plate is more likely to fracture before any of the soft tissues are ruptured or damaged. Obvious swelling and bruising are signs of a possible fracture, especially in children younger than 13.
The surgeon is looking for the type of fracture present, especially if there is a Salter-Harris fracture that involves the epiphyseal plate or “growth plate” of a bone. It is a common injury the long bones of children. Any fracture that interferes with the growth plate can cause growth to stop and local fusion of the involved bone. Therefore, these injuries can cause deformity of the joint.
Since Salter-Harris fractures are fractures through a growth plate they are unique to children and skeletally immature teens. These fractures are classified according to the involvement of three levels of growing bone (the physis, metaphysis, and epiphysis). The classification of the injuries is important, because it directs the plan of care and provides clues to possible long-term complications.
There are different types of Salter-Harris ankle fractures named for the location of the fracture. For example, a Salter-Harris Type I fracture goes horizontally through the growth plate. In this injury, the width of the physis is increased. The growing zone of the physis is not usually injured so growth disturbance is uncommon. A Type II Salter-Harris ankle fracture goes through the physis and metaphysis; the epiphysis is not involved in the injury. It is the most common type of Salter-Harris fracture,
A type III fracture goes through the physis and epiphysis. This type of fracture crosses the physis and extends into the articular surface of the bone. Type IV goes through all three levels of bone (the metaphysis, physis, and epiphysis). Once the type of Salter-Harris fracture has been identified, the surgeon pays attention to whether or not the fracture is displaced (separated) or nondisplaced. This is a factor in treatment decisions as well.
Most nondisplaced fractures can be treated conservatively without surgery. A cast is placed around the lower leg and foot. The child is not allowed to put weight on that leg for four to six weeks. A displaced fracture is reduced (set back in place) whenever possible without surgery. Sometimes surgery is required in which case the bones are reduced and held together with hardware (e.g., wires, metal plates, screws).
If the fracture cannot be reduced quickly and easily there is a risk of premature growth arrest. Surgeons tend to err on the side of caution and opt for surgery under general anesthesia to reduce the risk of this and other complications. The larger the gap between the bones, the more likely displacement cannot be reduced easily, thus requiring operative care.
In summary, physeal (ankle) fractures of the lower portion of the tibia and/or fibula are fairly common in children and must be evaluated and treated carefully to avoid disturbing growth of the bone. Terrible complications can be avoided by recognizing which type of Salter-Harris fracture is present and providing appropriate treatment. Closed reduction (without anesthesia and surgery), open reduction (with anesthesia and surgery), with or without fixation, the use of a long or short leg cast, and follow-up will all be determined by the surgeon in accordance with the classification of the ankle fracture.