Ankle fractures are common injuries, but their severity compared with other foot and lower leg fractures makes them somewhat unique. The ankle is where the body translates motion of the leg onto the ground by connecting a vertical leg with the horizontal foot. There are three bones that make up the ankle joint. The top of the joint consists of the end of the shin bone, called the tibia. This is supported by the end of the smaller fibula bone, which forms the outer side of the top of the ankle joint. The bottom of the joint, also known as the dome of the ankle, is created by the talus bone in the foot. Together, these three bones form a joint that allows the ankle to bend up and down, along with a lesser degree of rotation. There are strong bands of tissue called ligaments that bind the joint together, and keep it held in place.
When a significant enough twisting force is placed on the foot, the ankle will bend. If this force is stronger than the binding strength of the ligaments, they will tear. This is the essence of an ankle sprain. As this force increases, the bones will also crack under the pressure. Ankle fractures have several different mechanisms depending on how the foot rotates on the ankle during the injury. The tibia and fibula can fracture independently or at the same time, and can be a simple chip all the way up to a spiral fracture that moves the bone out of place. The tibia can even fracture in two different places.
The problem lies when the bone moves out of position. The ankle has to function perfectly in place, and any displacement leads to ankle instability and eventual arthritis. The key to repairing these fractures is to ensure that the ankle is in as close to a normal position as possible, and hold it there while the bone mends. Sometimes only a cast or walking boot is necessary to hold the bone in place if the fracture is minimal enough. However, many cases require surgery to obtain the best result. The goal of surgery is to bring the ankle bones back to a normal position, and then use hardware (usually a combination of metal plates and screws) to keep the bone stable. As the ankle is protected exteriorly by a cast, the bone will mend and ideally the ankle will stay in a normal position, lessening the likelihood of arthritis developing. This recovery can take place over the course of six weeks to three months.