The term pilon is also known as a hammer fracture occurs when one bone is driven into another bone with force. The bone may be broken into more than one piece. This is a comminuted pilon fracture. It often requires one or more operations to repair the damage. In 10 percent of cases, fusion of the joint is needed.

Pilon fractures can affect the spine and either bone in the lower leg (tibia or fibula). The most common pilon fracture affects the lower end of the tibia. The break occurs across the entire bone and into the ankle joint. It results from a high-energy, loading injury from the foot up into the bone. Car accidents, skiing injuries, and falls during horseback riding are the most commonly reported cause of pilon fracture.