The calcaneofibular ligament is a strong cord of tissue that helps to support the ankle joint. It connects the lower part of the fibula, the bone on the outside of the lower leg, to the calcaneus, or heel bone. Ankle injuries are common, and the calcaneofibular ligament is the second most frequently damaged of all ankle ligaments. Most often, it is damaged when the ankle twists over on itself in an inward direction, causing a sudden stretching or tearing of the ligament on the outside of the joint.
When a person is standing normally, the calcaneofibular ligament remains quite slack. One of the functions of the ligament is to support what is known as the subtalar joint, between the talus and the calcaneus. The talus is the ankle bone, which articulates with the lower ends of the leg bones, known as the tibia and fibula, above, and the calcaneus below.
Inversion, where the ankle turns inward on itself, is normally limited by the presence of the calcaneofibular ligament on the outside of the ankle. Taking part in sports that involve running and jumping movements, or slipping on uneven ground, may cause the ligament to tear. Typically, what is known as the anterior talofibular ligament, which connects the talus and fibula, is injured at the same time.
Following a calcaneofibular ligament sprain, people will often relate that they were running on an uneven surface or landing after a jump when the injury occurred. In some cases, the person simply stumbles and the ankle twists over. Sometimes, people may have experienced similar damage before, because once the ligament has been torn or stretched, it makes injuries more likely to happen in the future.
Symptoms associated with calcaneofibular ligament damage include pain and swelling on the outside of the ankle, bruising and problems placing weight on the joint. Occasionally, cracking sounds are heard due to ligaments tearing or pieces of attached bone breaking. The ankle joint may also become unstable in the case of more severe injuries.
Initially, a sprained calcaneofibular ligament is treated by resting the ankle, bandaging it firmly and applying ice. It is usually necessary to remain with the foot in an elevated position as much as possible until any swelling reduces. A more serious sprain, where the ligament is torn, may be treated using surgery in the case of younger patients. In older patients, a cast may be used to support the ankle joint until the calcaneofibular ligament has healed. For all patients, it is important to begin an exercise program to strengthen the muscles around the ankle as soon as possible.