Ankle Sprains

Sprains are injuries to the ligamentous structures of the ankle. About 85% of ankle sprains involve the lateral ligaments; medial and syndesmosis sprains make up the remaining 15%. Diagnosis is based primarily on history and physical examination, although radiographs are often helpful. Advanced diagnostic testing is not usually necessary. The family physician must be aware of the many potential pitfalls in the diagnosis of ankle sprain as well.

Lateral Ankle Sprains

The anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and posterior talofibular ligament (PTFL) are the three ligaments of the lateral ankle (Fig. 30-37). The ATFL primarily restricts anterior motion of the talus within the ankle mortise; the CFL restricts inversion; and the PTFL restricts posterior translation. The most common mechanism of lateral ankle sprain is an inversion ankle injury. Inversion events with the ankle in a plantar-flexed position often lead to ATFL injury (Fig. 30-38), whereas inversion events with the ankle in a dorsiflexed position more often lead to CFL injury (Fig. 30-39). Patients present due to ankle pain that may be associated with swelling, bruising, decreased motion, and increased pain with weight bearing, if able.

Examination begins with observing the patient's gait; a limp is often noted. Gross observation of the foot and ankle often reveals lateral edema and ecchymosis. Active motion may be severely restricted. Neurovascular structures are usually normal. Along with palpation of the ATFL, CFL, and PTFL, important structures to palpate on the lateral aspect

Cfl Ligament

talocalcaneal ligament

Figure 30-37 Anatomy of lateral ankle ligaments.

(From Nicholas J, Hershman E. The Lower Extremity and Spine in Sports Medicine, vol 1, 2nd ed. St Louis, Mosby, 1995, p 424)

talocalcaneal ligament

Figure 30-37 Anatomy of lateral ankle ligaments.

(From Nicholas J, Hershman E. The Lower Extremity and Spine in Sports Medicine, vol 1, 2nd ed. St Louis, Mosby, 1995, p 424)

Palpation Atfl

ligaments.

(From Meyer JM, Garcia J, Hoffmeyer P, et al. The subtalar sprain: a roentgenographic study. Clin Orthop 1988;226:169-173.)

ligaments.

(From Meyer JM, Garcia J, Hoffmeyer P, et al. The subtalar sprain: a roentgenographic study. Clin Orthop 1988;226:169-173.)

of the ankle include the fibula (entire length), peroneal tendons, lateral process of the talus, neck of the talus, cuboid, and base of the fifth metatarsal. Stress testing is performed to assess the integrity of ligamentous structures. The anterior drawer test translates the talus within the mortise and assesses the ATFL, performed with the ankle in slight plantar flexion to place the ATFL under tension while decreasing CFL tension. Both the amount of excursion compared to the opposite side and the end-point feel to the test are important determinants in the evaluation. The CFL is tested by the talar tilt. The ankle is placed in a neutral position, putting tension on the CFL and decreasing tension on the ATFL. The talus is then inverted within the mortise while the examiner assesses excursion and end-point feel. Once again, these findings are compared to the opposite side to determine severity of injury.

Subtalar Sprain
(From Meyer JM, Garcia J, Hoffmeyer P, et al. The subtalar sprain: a roentgenographic study. Clin Orthop 1988;226:169-173.)

In the United States, patients presenting for ankle injury often undergo radiographic evaluation, but the utility of routine radiographs to evaluate ankle injury is under debate. Well-designed studies from Canada have shown that many patients with ankle injury can be managed safely without routine radiographs. Indications for lateral ankle radiograph include age under 18 or over 55; inability to bear weight for four consecutive steps, either immediately after injury or in the examination room; and pain over the posterior portion of the distal 6 cm or at the tip of the fibula (Stiell et al., 1992, 1993). If pain is noted in the proximal or midshaft fibula, tibia/fibula films should be obtained, and pain over the base of the fifth metatarsal indicates the need for foot radiographs.

Various scales are available to grade ankle injuries, and interexaminer variability is high. The most common scale is mild (grade 1), moderate (grade 2), and severe (grade 3). However, grading does not significantly affect treatment, complication rates, or long-term outcomes. Grading may have a predictive role in duration of recovery.

Treatment of lateral ankle sprains has changed drastically over the past 25 years. Complete immobilization and rest were once thought to be important initial components of treatment. Currently, early mobilization with an external support device and rehabilitation are common therapies. Early immobilization may lead to greater stability and patient compliance, and the risk for early reinjury is low. In the early mobilization and rehabilitation plan, recovery tends to occur slightly quicker (based on full return to work), and early discomfort may be decreased (Eiff et al., 1994; Karlsson et al., 1996). With immobilization, the ankle joint can become stiff and lead to muscle atrophy. This may require a prolonged postimmobilization program focused on regaining motion and strength. Long-term outcomes of early mobilization and immobilization treatment plans are not significantly different.

Basic stages of treatment include early external support and, depending on severity, limited weight bearing, pain control, reducing swelling with ice and elevation, and maintaining motion. Once the initial acute injury subsides, weaning from supportive devices such as crutches, walking boots or casts should be done and formal rehabilitation initiated. Rehabilitation should focus on motion, strength, and proprioception activities. The final phase of rehabilitation is reintroduction of sport-specific tasks and return to sport. Participation in a prevention training program with a focus on balance and proprioception reduces the incidence of ankle sprain without increasing the incidence of other injuries (Bahr et al., 1997). Bracing the ankle on return to sport may reduce the risk of recurrent injury. Whether bracing reduces the risk of an initial sprain is under debate (Sitler et al., 1994; Surve et al., 1994).

When treating skeletally immature patients, it is important to remember that physeal plate fractures through the distal fibula result from the same mechanism as an ankle sprain. If the physical examination reveals tenderness along the distal fibular growth plate, a growth plate fracture must be considered, even if the radiographs are negative. In this case, a short period of immobilization followed by repeat imaging in 2 weeks is appropriate.

Medial Ankle Sprains

The main ligament on the medial side of the ankle is the deltoid ligament (Fig. 30-40). Deltoid injuries are typically caused by an eversion mechanism. Medial ankle examination is similar to that of the lateral ankle. Observation of gait usually reveals a limp, and gross observation of the ankle often reveals medial edema but no other deformity. Active motion may be severely restricted, and neurovascular status should be normal. Careful palpation of bony, tendinous, and ligamentous structures of the medial ankle include the deltoid ligament, medial malleolus, medial process of talus, neck of talus, medial cuneiform, cuboid, navicular, and medial ankle tendons (posterior tibialis, flexor digitorum longus, and flexor hallucis longus).

Stress testing of the deltoid ligament is performed by an eversion stress test, usually performed with the ankle in neutral position. Amount of excursion compared to the opposite side and the end-point feel determine the severity of the injury. Deltoid function can also be assessed by stressing the ankle, translating it from medial to lateral and assessing for instability or mortis widening. Any offset increases the stresses on the articular cartilage and increases the risk of arthritis. Obtaining radiographs in the patient with medial ankle injury is decided on a case-by-case basis but should be done more readily than for the typical lateral ankle sprain. Treatment plans are similar to those for lateral ankle sprains. It is widely believed that medial sprains take longer to heal than their lateral counterparts.

Syndesmosis Ankle Sprains (High Ankle Sprains)

The ankle syndesmosis is the area of the distal tibia-fibula joint. The five soft tissue structures in the syndesmosis region include the anterior tibiofibular, posterior tibiofibular, transverse tibiofibular, and interosseous ligaments and the interosseous membrane; of these, the anterior tibiofibular ligament is most often injured. Syndesmosis sprains account for 1% to 18% of ankle sprains, with a higher incidence in high-level athletes. Syndesmosis sprains are generally thought to take longer to heal than lateral or medial sprains (Hopkinson et al., 1990), and persistent ankle pain and persistent dysfunction are more common (Gerber et al., 1998);

Body Diagram Female
(From Nicholas J, Hershman E. The Lower Extremity and Spine in Sports Medicine, vol 1,2nd ed. St Louis, Mosby, 1995, p 424.)

syndesmosis injuries are often associated with fractures. The mechanism of injury is different than for the more common lateral and medial sprains; syndesmosis sprains are most often caused by forceful external rotation and hyperdorsi-flexion injuries.

Physical examination often reveals an antalgic gait limp and anterolateral ankle swelling over the anterior tibiofibular ligament just proximal to the joint line. Ecchymosis is often a delayed finding and is usually noted proximal to the ankle joint, in contrast to that noted in lateral and medial sprains, which is often below the ankle and occasionally throughout the foot. Careful palpation reveals tenderness directly over the anterior tibiofibular ligament. Syndesmosis injuries may be present along with medial ankle injury, so tenderness over deltoid ligament may be noted as well. Be sure to palpate the proximal fibula, because extreme forced external rotation may lead to Maisonneuve's fracture (proximal fibular fracture). Strength testing is often limited by pain, and neurovas-cular status remains intact.

Special stress tests to evaluate the syndesmosis include the squeeze, external rotation, and dorsiflexion-compression tests. The squeeze test is performed by compressing the fibula and tibia above the midpoint of the calf (Hopkinson et al., 1990) (Fig. 30-41). The test is positive if compression causes pain in the region of the syndesmosis ligament. The external rotation test is performed with the knee at 90-degree flexion and the ankle in neutral position. An external rotation force is applied to the foot while stabilizing the remainder of the leg. Pain in the anterior tibiofibular region is a positive test. The external rotation test is thought to be the most reliable of the common clinical tests used to diagnose syndesmosis sprains.

Because of the risk of concurrent fracture with syndesmosis sprains, radiographs should be obtained. Plain radiographs are adequate to assess for frank diastasis (widening between fibula and tibia). Stress radiographs may be necessary to discover latent diastasis. The three major radiographic considerations are the (1) tibiofibular clear space, the distance between medial border of fibula and lateral border of posterior tibia,

Distal Tibiofibular Syndesmosis DistanceDiastasi Tibio Peroneale Distale

Figure 30-41 Squeeze test.

(From Hopkinson WJ, St. Pierre P, Ryan IB, et al. Syndesmosis sprains of the ankle. Foot Ankle int l990;i0:325-330. Copyright American Orthopedic Foot and Ankle Society, 1990.)

Figure 30-41 Squeeze test.

(From Hopkinson WJ, St. Pierre P, Ryan IB, et al. Syndesmosis sprains of the ankle. Foot Ankle int l990;i0:325-330. Copyright American Orthopedic Foot and Ankle Society, 1990.)

measured 1 cm above tibial plafond; (2) tibiofibular overlap, the maximum amount of overlap of distal fibula and anterior tibial tubercle; and (3) medial clear space, the distance between medial malleolus and medial border of talus, measured 1 cm below tibial plafond (Fig. 30-42).

Additional testing such as CT scan can be helpful early in the workup to look for occult fracture and later to assess for heterotopic ossification, a common complication of syndesmosis sprains. MR scan is sometimes used and has a high sensitivity and specificity for detecting anterior and posterior tibiofibular ligament injuries (Oae et al., 2003).

Initial treatment begins with protection of the joint, relative rest, ice, compression, and elevation. Various modalities to reduce swelling and inflammation can be used. Rehabilitation includes ROM exercises, strengthening and balance exercises, and proprioception training. Activities can be advanced when pain is reduced, and rehabilitation exercises can be performed pain-free. Return to full activities can be entertained when the patient has full motion, full strength, no tenderness on examination, and no functionally limiting pain.

Latent diastasis can be treated nonoperatively if reduction can be achieved. Therapy includes immobilization with non-weight bearing followed by progressive weight bearing beginning at about 4 weeks and full weight bearing by 2 months. Surgery is needed if reduction cannot be achieved or if diastasis recurs despite immobilization. Frank diastasis is treated surgically.

A common adverse outcome of syndesmosis sprain is heterotopic ossification. Plain radiographs are adequate to make the diagnosis in patients with persistent pain (Fig. 30-43). Affecting 25% to 90% of patients, heterotopic ossification may or may not be symptomatic. Ossification may cause pain without causing frank synostosis. The discomfort

Heterotopic Ossification Fibula

Figure 30-42 Normal anteroposterior radiograph of the ankle revealing a normal tibiofibular clear space (i), normal tibiofibular overlap (2), and normal medial clear space (3). Significant mortise widening is noted with widening of all three of these parameters. Note the distal fibula fracture. This injury is best treated with internal fixation of the fracture and stabilization of the ankle mortise with a syndesmosis screw. B, Football eversion injury shows widening medial mortise with associated deltoid tear, widening distal tibiofibular syndesmosis, high fibular fracture, and small posterior malleolus fracture (not seen here). (A courtesy James L. Moeller, MD; B from Nicholas J, Hershman E. The Lower Extremity and Spine in Sports Medicine, vol i, 2nd ed. St Louis, Mosby, 1995, p 465.)

Figure 30-42 Normal anteroposterior radiograph of the ankle revealing a normal tibiofibular clear space (i), normal tibiofibular overlap (2), and normal medial clear space (3). Significant mortise widening is noted with widening of all three of these parameters. Note the distal fibula fracture. This injury is best treated with internal fixation of the fracture and stabilization of the ankle mortise with a syndesmosis screw. B, Football eversion injury shows widening medial mortise with associated deltoid tear, widening distal tibiofibular syndesmosis, high fibular fracture, and small posterior malleolus fracture (not seen here). (A courtesy James L. Moeller, MD; B from Nicholas J, Hershman E. The Lower Extremity and Spine in Sports Medicine, vol i, 2nd ed. St Louis, Mosby, 1995, p 465.)

comes from an inflammatory response in early stages, then from pressure on adjacent bones. Fracture of the ossification is also a potential cause of pain. Frank synostosis can occur. Pain typically results from restricted tibiofibular motion, particularly during full ankle dorsiflexion. Conservative treatment may reduce the pain, but surgical excision may be required (Hopkinson et al., 1990; Taylor et al., 1992).

Figure 30-43 Heterotopic ossification noted after syndesmosis ankle sprain.

(Courtesy James L. Moeller, MD.)

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