Ankle Sprain

Inversion injury to the ankle is one of the most common injuries in sports, as well as a very common emergency room diagnosis. The mechanism of injury is usually a turning in of the ankle, accompanied by pain and sometimes a palpable pop.

Anatomy

The ankle joint is flexible enough to permit a wide range of motion, yet strong enough to bear the weight of the entire musculoskeletal system. It consists of the talus within a box-shaped mortise formed superiorly and medially by the tibia, and laterally by the fibula.

Three ligaments stabilize the lateral ankle: the anterior talofibular, the calcaneo-fibular, and the posterior talofibular. The anterior talofibular ligament is under strain when the ankle is plantar flexed, inverted and internally rotated. Since most ankle sprains occur in plantar flexion and inversion, the anterior talofibular ligament is most frequently injured. The calcaneo-fibular ligament is under increased strain when the ankle is dorsiflexed and inverted and can also be injured during more severe inversion injuries. The posterior talofibular ligament is under greatest tension when the ankle is dorsiflexed and externally rotated and is rarely injured.

An ankle sprain occurs when ligaments in the ankle joint are stretched or torn. Depending upon the amount of ligament tearing, a sprain can be mild, moderate, or severe. The accumulation of fluid in a ligament injury gives rise to the characteristic symptoms of the sprained ankle: pain, swelling and ecchymosis.

Classification

Ankle sprains are classified into three grades. Grade I sprains have minimal tenderness and no measurable instability. Grade II sprains are considered partial tears and may demonstrate some limited instability. Grade III injuries involve a complete tear of the ligament with instability most likely when two ligaments are involved.

Grade I injuries are the most common. The anterior talofibular ligament is stretched but not torn. There is little swelling or instability. Treatment is non-surgical: Rest, Ice, Compression and Elevation (RICE). After the initial phase in the first 48 hours, weight bearing as tolerated is commenced with either a protective brace or taping. Isometric exercises are begun as well as a balance board regimen to reestablish strength, range of motion, and proprioception. The vast majority of these injuries return to full function.

Grade II injuries are partially torn ligaments. The ankle usually swells immediately and there is marked ecchymosis. This type of injury may require a three to six week rest before returning to full activity. The RICE regimen is used acutely in the first 48 hours and then weight bearing, protective bracing and resistive exercises are introduced slowly as pain allows.

In Grade III injuries the ligaments are more seriously torn. If recurrent, they may require ligament repair to prevent further injury. A variety of surgical options are available when reconstruction is needed.

Rehabilitation

Surgery is rarely required for a properly rehabilitated ankle sprain. Grade III injuries may require 8-12 months for the ligaments to fully heal and for the patient to return to full activity.

The consequence of a poorly rehabilitated ankle injury is weakness leading to instability. Rehabilitation should begin after the initial phase of injury is treated with the RICE regimen. The patient can walk on the ankle as soon as it feels comfortable. Crutches should be used as a partial support until full weight bearing begins. Additional support for the ankle in the form of a brace, wrapping or taping may be needed. In more severe injuries, casting may also be appropriate.

A good rule of thumb is that pain should be the patient' s guide as to how much activity is enough. Stiffness is a common sequelae in the early phases of an ankle sprain, therefore range of motion is the first priority. A good initial exercise is to rest the heel on the floor and move the ankle through a full range of motion. Writing the alphabet with one' s toes will accomplish the same goal.

After regaining full range of motion, strengthening is a priority. The patient should not return to full activity until full weight can be borne on the injured ankle. The patient should be able to rise on his or her toes in complete plantar flexion while supporting full weight. Another measure of complete recovery is standing on the injured ankle for 20 seconds and hopping on the toes ten times. Initially, jogging in a straight line will be possible. As strength increases, lateral movement, cutting and other sports related activity will be possible. Protecting the ankle for the first six months after the injury is strongly advised.

Impingement in the lateral gutter can cause lingering pain a the anterolateral aspect of the ankle after an inversion injury and ligament disruption. This is caused by the talus abutting on scar tissue formed from the torn portion of the injured ligament. If pain does not respond to conservative measures, then surgical debridement may be necessary.

Medial Ankle Sprain

Injuries of the medial ankle ligament or the deltoid ligament are extremely uncommon without fracture. An X-ray may reveal widening of the medial ankle joint which can reflect tissue trapped in the joint producing an asymmetry of the mortise. In this case, an arthrotomy will be needed to remove the interposed soft tissue.

Medial ankle sprains need to be closely evaluated since isolated deltoid injuries are so uncommon. These "medial ankle sprains" are usually injuries to the posterior tibia1 tendon. If untreated, these can progress to a pes planovalgus or acquired flat foot deformity which is severely disabling to the patient. Early management of the posterior tibia1 tendon injury may prevent this deformity.

X-rays of all but the most minor ankle sprains should be performed to eliminate the possibility that fracture has occurred. X-rays should include AI' , lateral and mortise views of the ankle.

The proximal aspect of the lateral calf should be checked for tenderness because a proximal fibula fracture in association with an ankle injury can indicate an injury to the tibial-fibular syndesmosis. Disruption of the syndesmosis most often occurs with ankle fractures but it also can occur with dorsiflexion external rotation injuries and may present as a sprain. If the ankle mortise has been disrupted in association with one of these injuries, then surgery is required to restore symmetry of the ankle mortise. Injuries without widening of the ankle mortise can be treated non-surgically with a cast.

Any isolated "medial ankle sprains" with lingering symptoms need to be referred for evaluation to an orthopaedic surgeon.