The ankle is an excellent example of interplay between bone and ligamentous structures and their protective relationship upon one another. The ankle joint is maintained by the shape of the talus (first bone of the foot) and its tight fit between the tibia and fibula. In the neutral position, there are strong bony constraints. With increasing plantar flexion, the bony constraints are decreased and the ligaments are more susceptible to strain and injury. The three major ligament groups that support the ankle include the tibiofibular ligaments, the deltoid ligament complex medially and the lateral ligament complex.

Lateral Ankle Ligaments

The lateral ligament complex of the ankle consists of three separate ligaments: the anterior talofibular ligament, the posterior talofibular ligament and the calcaneofibular ligament. These ligaments stabilize the ankle, and serve as a guide to direct ankle motion.

ATF - Anterior Talofibular Ligament

CF - Calcaneal Talofibular Ligament

PTF - Posterior Talofibular Ligament

The primary function of the anterior talofibular ligament is to restrain anterior displacement of the talus in respect to the fibula and tibia. It assumes a course parallel to the axis of the leg when the foot is plantar flexed (pushed down) and thereby functions as a collateral ligament. Because most sprains occur when the foot is in plantar flexion, this ligament is most frequently injured when the foot inverted (turned in).

The calcaneal fibular ligament ligament runs from the tip of the fibula to the tubercle in the calcaneus. The primary function of the calcaneofibular ligament is to restrain inversion of the calcaneus (heel bone) with respect to the fibula. The calcaneofibular ligament and the anterior talofibular ligament play significant roles in different positions of the ankle. The calcaneofibular ligament is the main lateral stabilizer of the ankle in both neutral position and dorsiflexion. The reason that the anterior talofibular ligament is the most commonly injured of these ligaments is that the majority of the sprains occur during flexion and inversion of the foot. The anterior talolfibular ligament is usually the first to suffer disruption followed by the calcaneofibular ligament and subsequently the posterior talofibular ligament.

The posterior talofibular ligament arises from the posterior medial aspect of the lateral malleolus (fibula) and runs posteromedially to the talus. The primary function of the posterior talofibular ligament is to resist posterior displacement of the talus. This ligament is under greater strain in full dorsiflexion of the ankle. The posterior talofibular ligament is rarely torn in an ankle sprain because bony stability protects the ligaments when the ankle is in dorsiflexion.

Medial Ankle Ligaments

Deltoid Ligament: The deltoid ligament is triangular in shape and consists of a superficial and deep layer which connect the talus to the medial malleolus.

The superficial part of the deltoid ligament consists of the tibionavicular ligament, the tibiocalcaneal ligament in the middle, and the superficial tibiotalar ligament posteriorly. The deep layer of the deltoid consists of the anterior and posterior tibiotalar ligaments. The deep layer is more important in ankle stability than superficial layer. During ankle motion all parts of the deltoid ligament function as a unit providing support to the ankle.

Ankle Sprains

Ankle sprains are the most common sports-related injuries. It has been estimated that there is about one inversion to the ankle per 10,000 persons per year in the United States or approximately 23,000 ankle sprains per day in the United States. Basketball, volleyball, soccer, football and other sports events including running and jumping activities are particularly plagued by these injuries. Ankle sprains constitute about 25% of all injuries in these sports. Inversion injuries (turning in of the foot) constitutes 85% of all ankle sprains (65% result in a tear of the anterior talofibular ligament and 20% tear of both the anterior talofibular ligament and calcaneofibular ligament). Sprains of the deltoid ligament caused by eversion (turning out of the foot) constitute 5% of ankle sprains, and syndesmosis injuries tearing of the anterior inferior tibiofibular ligament binds the tibia and fibula together) account for the remaining 10%.

The most typical injury mechanism of an ankle sprain is when the body weight lands with the foot in plantar flexion, inversion, and adduction. The bony stability of the ankle is diminished in this position and the anterior talofibular ligament and calcaneofibular ligament absorb the stress.

Isolated injuries to the deltoid ligament are rare. When they occur usually there is only a partial ligament tear in the anterior part of the ligament. Complete deltoid ligament tears occur most commonly in combination with ankle fractures.

Classification

Traditionally ankle sprains have been classified as grade I (mild), grade II (moderate), and grade III (severe). A grade I injury signifies stretching of the ligaments with some fibers torn, but no frank disruption. Clinically, these injuries present with only mild swelling or tenderness, minimal or no functional loss, and no joint instability.

A grade II ankle sprain signifies a moderate injury to the ankle ligaments, frequently with a complete tear of the anterior talofibular ligament laterally and a partial tear of the calcaneofibular ligament. Examination shows a restricted range of motion with moderate swelling, bruising, and associated tenderness. There also may be mild joint instability.

A grade III injury is complete ligament rupture with marked swelling, hemorrhage, and tenderness. There is loss of function and marked abnormal joint motion and instability. Most commonly, this represents a complete disruption of both the anterior talofibular ligament and the calcaneofibular ligament laterally. An accompanying tear of the posterior talofibular ligament would present as an ankle dislocation. Moderate to severe laxity to anterior drawer inversion is usually present but may not be elicited because of swelling and guarding during examination.

Physical Exam

It is often difficult to determine the degree of ligamentous injury sustained when examining the patient with an acute sprain. The site of the tear can be determined by palpating the point of maximal tenderness. Frequently, the most tender spot is at the tip of the lateral malleolus over the anterior talofibular ligament and the calcaneofibular ligament. The clinical tests for ankle instability are not very reliable. The two most commonly used tests are the anterior drawer test and inversion stress test.

Ancillary Studies

Roentgenograms should be obtained to rule out a fracture. Placing the ankle under stress and taking xrays is another method to determine the degree of ankle sprain. Some physicians also use arthrography (injection of dye in the ankle) to diagnose acute lateral ankle injuries.

Treatment Of Acute Sprain

There is a general consensus that proper treatment of a grade I or II ankle sprain is nonoperative management. The treatment program consists of functional rehabilitation, including the RICE principle (rest, ice, compression and elevation). As soon as possible, the patient is started on a program of physical therapy to begin range of motion, weight bearing, and neuromuscular training. The ankle is also protected with taping, lace up ankle support or functional ankle brace, depending upon the degree of injury. Grade I injuries usually return to participation within one week and grade II injuries within two weeks after treatment with this regimen.

The treatment of grade III sprains of the lateral ligament complex is more controversial. Both operative and nonoperative methods of treatment have been successful. At this time, most sports medicine physicians would treat grade III ankle sprains conservatively with functional rehabilitation. Controlled mobilization and loading have been shown to have a positive effect on the weight bearing capacity and healing processes of the ligaments. Only 10-20% of grade III ankle sprains may require secondary repair. If conservative treatment fails and surgery is required, a good result may be obtained even years after the initial injury. In addition, functional treatment saves the patient from tissue trauma caused by surgery.

Functional treatment also results in enormous financial savings compared to surgery.

Chronic Lateral Ankle Instability

Approximately 10 to 30% of patients with lateral ligament injury may have chronic symptoms of persistent pain, swelling, giving way, and stiffness after either conservative or operative treatment. These problems maybe associated with mechanical or functional instability. Mechanical instability, indicating incompetence (increased laxity) of the lateral ankle ligaments, may be assessed with physical examination or stress radiographs. Unfortunately, there is a poor correlation of stability testing to the perception of giving way. Because significant variation in ankle laxity of normal subjects and it is not known how much pathologic laxity can exist in the ankle without resulting in sumptoms of giving way during activity.

Treatment

The initial treatment for chronic lateral ankle instability is functional rehabilitation including restoring range of motion, strengthening the peroneal muscles, and proprioception training. The ankle should also be protected with bracing or taping during strenuous activities.

Failure of conservative treatment is an indication for surgical reconstruction. More than thirty surgical procedures have been described to treat lateral ankle instability. 

Currently the most popular procedures include either anatomic repair or reconstruction of the lateral ankle ligaments.

Repair of Ankle Ligaments

The Christman-Snook procedure is commonly used to reconstruct the lateral ankle ligament. 

Lateral Ankle Reconstruction

One half of the peroneus brevis tendon is routed through the fibula into the calcaneus reconstructing the anterior talofibular and calcaneofibular ligaments. A high success rate may be obtained with either an anatomic repair or lateral reconstruction.

Functional Instability

Functional instability is a subjective feeling of giving way or recurrent sprains during physical activity. It is not associated with laxity of the lateral ankle ligaments. The incidence of functional instability has been reported to occur in 15-60% of patients with injuries to the lateral ankle ligaments.

The cause of this condition is unclear. It may be related to neurological problems (proprioception, reflexes and muscular reaction time), muscular or mechanical factors. The treatment of functional instability in the ankle follows the same principles of ankle rehabilitation. The importance of proprioception (sensing of joint movement) and muscle training must be emphasized.

Treatment / Ankle Taping

Ankle taping and braces are becoming increasing popular. Taping is of value in preventing ankle displacement. However, adhesive tape loses up to 50% of its original support after ten minutes of exercises. Studies comparing prophylactic ankle taping and a lace up ankle support demonstrated that initially taping provided the best support. Even so, after a short period of time, there was no significant difference in the degree of support provided by taping and a lace up support. Another study demonstrated that a lace up ankle support was more effective in preventing sprains than ankle taping.

Ankle Arthroscopy

Arthroscopy of the ankle has become a widely accepted procedure for the diagnosis and treatment of various intraarticular disorders. 

The picture at the left is an arthroscopic view of the talus, tibia and fibula. 

The indications for ankle arthroscopy are:

1. Evaluation of post-traumatic ankle without definitive diagnosis.

2. Removal of loose bodies.

3. Debridement, curetting or drilling of chondral or osteochondral defects of the talus.

4. Evaluation and treatment of osteochondral fractures of the talar dome.

5. Excision of synovial ligamentous tissue, including synovectomy.

6. Lysis of adhesions.

7. Irrigation and debridement of septic arthritis of the ankle.

8. Excision of osteophytes