Ankle Impingement

Ankle impingement occurs when soft tissues around the ankle are pinched or nipped. Impingement mainly happens when the ankle is fully bent up or down, leading to pain either in the front or back of the ankle joint. Problems near the front of the ankle are usually associated with past ankle injuries. Impingement at the back of the ankle occurs in athletes who engage in forceful plantarflexion, such as ballet dancers.

Anterior Ankle Impingement

Anterior ankle impingement is a common condition in soccer players. Basically it consists of bone spurs forming at the front of the ankle after repetitive sprains or contact injuries. The major symptoms are pain at the front of the ankle and a reduced range of forward ankle movement. The usual treatment of anterior ankle impingement includes cortisone injections and arthroscopic surgery.

Posterior Ankle Impingement

Posterior impingement occurs in the back of the ankle. It is most common in athletes who must continually rise up on their toes, pointing their foot downward into extreme plantarflexion. Posterior ankle impingement can also happen in other athletes. But this is uncommon, because forceful plantarflexion is rarely required in other sports.

What Causes Ankle Impingement?

People who have had several mild ankle sprains or one severe ankle injury are more likely to develop anterior impingement. This is especially true for athletes who repeatedly bend the ankle upward (dorsiflexion), such as baseball catchers, basketball and football players, and dancers. Over time, irritation along the front edge of the ankle can lead to impingement.

Irritation in the lower edge of the anterior inferior tibiofibular ligament and the front of the anterior talofibular ligament can thicken these ligaments. The irritated ligaments become vulnerable to getting pinched between the tibia and talus as the foot is dorsiflexed. These ligaments may also begin to rub on the joint capsule of the ankle. This can inflame the synovial lining of the capsule, a condition called synovitis.

A similar problem can happen after an ankle sprain. As the torn or ruptured ligament heals, the body responds by forming too much scar tissue along the front and side of the ankle joint. This creates a small mass of tissue called a meniscoid lesion. Dorsiflexing the ankle can trap the tissue between the edge of the ankle joint, causing pain, popping, and a feeling that the ankle will give out and not support your body weight.

Over time, damage from past ankle sprains may also lead to the formation of small projections of bone called bone spurs. Bone spurs can form along the bottom ledge of the tibia bone or on the upper surface of the talus. As the ankle hinges into dorsiflexion, the bone spurs may begin to jab into the soft tissues along the front edge of the ankle joint, causing symptoms of anterior impingement.

The Presence of an Os Trigonum

A frequent cause of posterior ankle impingement is the presence of an os trigonum. In some people the lateral tuberosity is not united to the talus. The separate piece of bone is called an os trigonum. This separation of the os trigonum from the talus is usually not a fracture. About 15 percent of people have an os trigonum. An os trigonum sometimes causes problems of impingement in the back of the ankle.