The term ‘pilon’ was first used in 1911 by French radiologist Destot to describe the ankle joint. It is derived from the French word for ‘pestle’, and helps to describe both the shape of the ankle joint as well as the mechanism of this type of injury. Pilon fractures occur when axial compression is applied through the ankle joint, exceeding the amount of force that the ankle can transmit through the body. When this happens, a serious injury may occur, shattering the tibia and sometimes the fibula as well.
Pilon fractures are uncommon, accounting for 7% of all tibia fractures and less than 1% of all lower extremity fractures. They are an interesting subject, however, due to the orthopedic challenges that they present. Many pilon fractures will also be open fractures, meaning that the skin has been compromised in the injury and the bone may actually be visibly protruding from the skin. Higher impact injuries, such as from a motor vehicle accident or a fall from a height will involve a fracture of both the tibia and fibula. Lower impact injuries, such as skiing accidents, may only involve a fracture of the tibia. These fractures are generally intra-articular, which adds to their complexity.
Classification systems for pilon fractures include the Ruedi and Allgower classification, which was the first one described in 1969. Later, the AO/OTA classification was established in 1996, which gave further detail as to the extent of the injury. Both systems differentiate between number of fracture fragments, displacement of fracture fragments, and articular involvement. These systems are useful in communicating the extent of the injury, however little intra- and inter-observer agreement has been seen with the use of either of the two systems.
Diagnosis of pilon fractures is made with medical imaging. X-rays are typically ordered first, followed by a CT scan. CT scans will allow the foot and ankle surgeon to visualize the number of fracture fragments and the arrangement of the injury, and will help in planning the surgical correction.
Because of the type of injury that causes a pilon fracture, the patient is usually brought in to the emergency room and is treated first by the trauma team. This would include management of airway, breathing, circulation, disability, and exposure to any contaminants and/or toxins. Once the patient is stabilized, the fractures may be treated. There is a high correlation between pilon fractures and spinal fractures, so imaging should include the entire vertebral column.
While historically pilon fractures have been treated conservatively, most physicians would agree that treatment with surgery is necessary to regain function of the limb. Early reasons to avoid surgery were poor outcomes and increased risks involved with surgery, however, modern surgery has evolved to have a much greater success rate than in the past.
Surgical treatment of pilon fractures is most commonly done in a two-stage fashion. The first stage involves putting an external fixation device on the leg. These are done as either ankle-spanning (pins are placed through the talus, the bone that sits in the ankle joint) or as ankle sparring (no pins are placed through the talus). Today, ankle-sparring procedures have become more popular as they decrease damage to the joint itself. The external fixator is used to help realign the fracture fragments, and uses the theory of ligamentotaxis to do so. Once the fragments have bee realigned, and most of the initial swelling has decreased since the injury, a more definitive procedure may be performed to fix the ankle and leg
This commonly involves the use of either metal plates or an intramedullary nail, or both. Intrameduallry nails are long nails that are placed longitudinally through the bone. This gives the bone strength and helps to realign the fractures. The plates will also help to realign fragments, particularly of the fibula, should it be involved in the fracture. A variety of techniques may be used surgically, depending on the extent of the injury and the damage done to the bones.
Prognosis of pilon fractures depends heavily on the extent of injury. Numerous studies have shown that the more significant the injury, the greater chances of post-operative complications, infection, delayed union, malunion, and non-union. Good results may be seen with fractures that show minimal displacement and comminution (meaning that there are several fracture fragments), though unsatisfactory results are more commonly seen with more extensive comminution, joint involvement, and displacement of fracture fragments. Advances to surgical technique have made the outcomes more favorable in recent years, yet there is still an increased risk of post-operative sequelae with more extensive injury.
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