Definition

Ankle instability is a broad term which includes functional weakness of the muscles about the ankle, as well as tears of the ligaments which normally provide support.

Anatomy

The muscles of the outer aspect of the ankle include the peroneus longus and peroneus brevis muscles.  Both of these muscles are responsible for eversion of the foot, and resist inward twisting.

There are three (3) main ligaments on the lateral aspect of the ankle:

• Anterior Talofibular Ligament is the most commonly injured.

• Calcaneofibular Ligament prevents tilting of the ankle, and is injured in severe ankle sprains.

• Posterior Talofibular Ligament is rarely injured.

Symptoms

Symptoms may vary from occasional "popping" while walking, especially on uneven ground, to frank "giving way" and falling while participating in sporting activities.

Causes

Ankle instability may be the result of one acute traumatic event, or the result of multiple recurrent injuries to the ankle.

Mechanism

The mechanism of injury to the lateral ligaments of the ankle is inversion (twisting inward of the foot) such as occurs during walking or running activities.

Treatment

Initial treatment of ankle instability involves rehabilitation, with emphasis on strengthening of the muscle-tendon units with specific exercises and physical therapy.  Ankle braces may be used.  Modification of shoes to include lateral heel flares or lateral heel wedges may improve stability.

If instability persists, after completion of conservative protocol, surgical treatment may be required.  Surgery usually involves repair of torn ligaments and capsule.  This operation is referred to an ankle ligament reconstruction.  The peroneal tendons are often evaluated and cleaned of inflammatory tissue.