Ankle sprains are fairly common in adults but trauma to the ankle in children is more likely to cause a bone fracture than a sprain. These are challenging injuries because the growing child may still have an open physis (growth plate) that could be disrupted. The result can be deformity, a leg length difference, impingement, and overload of one side of the ankle.
In this article, pediatric orthopedic surgeons from the Cleveland Clinic in Ohio review types of physeal ankle fractures and their treatment. The Salter-Harris Classification system is used to determine type of fracture, amount of displacement, amount of growth left, and the best way to manage the problem.
Although the two main goals of treatment are to maintain optimum function and limit risk of physeal (growth plate) damage, the authors say that evidence is lacking as to the best way to accomplish these goals. Studies comparing treatment methods for each type of fracture with long-term outcomes are needed.
Until such results are available, the surgeon must rely on the patient’s history, the physical examination, results of imaging studies, and classification of the fracture to create a plan of care. Besides damage to the growth plate, trauma to the surrounding soft tissues must be assessed as well. Ligamentous damage can create an unstable ankle. But usually, the ligaments are stronger than the weak, growing physis. So in the growing child, physeal injury is more common than ligamentous damage.
The surgeon will look for any damage to the blood vessels, nerves, tendons, and muscles, and also rule out the presence of other bone fractures in the foot. A large amount of swelling may mean a delay in surgical correction or cast immobilization. The risk of infection and difficulties with wound healing are too great to intervene with early surgery. MRI and/or CT scans may provide details about the bone and soft tissue injuries that will help the surgeon plan the most appropriate surgery.
When using the Salter-Harris classification system, there are five major types of ankle fractures (I through V). Each number signifies the severity of the injury and the amount of growth plate involvement. The classification numbers also give an idea of the risk of growth arrest (e.g., low risk with Type I fractures, high risk with Type V). Fortunately, Type V fractures are rare.
The authors provided drawings and X-rays to show each of the Salter-Harris types of pediatric ankle fractures. They also included a second classification scheme (the Dias-Tachdijian classification system) to compare with the Salter-Harris method. There are detailed descriptions of each type of fracture and the recommended treatment for each one.
Three additional descriptors of pediatric ankle fractures are also discussed. These include transitional, Tillaux, and triplane fractures. Transitional fractures refer to the time period during which the growth plate starts to close (usually the last 18 months of growth). For girls, the physis closes and growth is completed by age 14. For boys, growth is usually finished by the time they are 16 years old.
Tillaux fractures go through the growth areas right into the joint itself. Treatment varies depending on whether or not the fracture is displaced (separated). Displaced fractures require surgery and long-term results are reportedly good. Later, there can be early degenerative (arthritic) changes.
And finally, triplane fractures are actually a subgroup of Salter-Harris type IV fractures. As the name suggests, triplane tells us the fracture goes through all three layers of bone and growth tissue (metaphysis, physis, epiphysis). The mechanism of injury is a shearing force. There can be a wide range in the amount of displacement. Treatment often requires screw fixation to create a stable union.
The main concern of this article is growth disturbance after ankle fractures that cause injury to the physis (growth plate). Growth arrest or early closure of the growth plates can cause deformities and leg length differences. The authors advise careful examination and evaluation in order to make an accurate diagnosis. Close follow-up after treatment for at least two years is essential. This is especially true for children who still have quite a bit of growth left at the time of the injury.
Children who are closer to the time of their full skeletal maturity do not need such close follow-up or further intervention. Children who develop bridges of bone across the growth plate before full growth is acquired may need surgery to remove the abnormal bone.