83: Ankle Sprain

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CHAPTER 83

Ankle Sprain

Brian J. Krabak, MD, MBA, FACSM

Synonym

Inversion sprain

ICD-9 Code

845.00  Sprains and strains of the ankle and foot

ICD-10 Codes

S93.401  Sprain of unspecified ligament of right ankle

S93.402  Sprain of unspecified ligament of left ankle

S93.409  Sprain of unspecified ligament of unspecified ankle

S93.601  Unspecified sprain of right foot

S93.602  Unspecified sprain of left foot

S93.609  Unspecified sprain of unspecified foot

Definition

Ankle sprain involves stretching or tearing of the ligaments of the ankle. Ankle injuries are a common cause of morbidity in the general and athletic population, with an estimated 25,000 ankle sprains requiring medical care in the United States per day [1]. Overall, ankle sprains are slightly more likely to occur in males (50.3%) than in females (49.7%) and nine times more likely to occur in younger than in older individuals [2]. In the high-school athlete, there are an average of 5.23 ankle injuries per 10,000 athlete-exposures, most often due to traumatic ligament injuries involving boys’ basketball, girls’ basketball, and boys’ football [3]. In the collegiate athlete, ankle sprains represent 15% of all athletic injuries and account for almost 25% of injuries of men’s and women’s collegiate basketball and women’s volleyball athletes [4,5].

Eighty-five percent of all ankle sprains occur on the lateral aspect of the ankle, involving the anterior talofibular ligament and calcaneofibular ligament (Fig. 83.1) [6]. Another 5% to 10% are syndesmotic injuries or high ankle sprains, which involve a partial tear of the distal anterior tibiofibular ligament. Identification of syndesmotic sprains is important; they may have a prolonged recovery compared with milder lateral ankle sprains and are more likely to require surgery. Only 5% of all ankle sprains involve the medial aspect of the ankle as the strong medial deltoid ligament is resistant to tearing. Most ankle sprains will recover during several weeks to months, depending on the grade of injury. It is estimated that 20% to 40% of ankle sprains result in chronic sequelae [7]. An ankle sprain that does not heal may be caused by injuries to other structures and will necessitate further investigation for other causes.

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FIGURE 83.1 Ligaments of the lateral ankle.

The exact structure torn will depend on the mechanism of injury. The most common mechanism of injury involves foot supination and inversion, resulting in a tear of the lateral ankle structures (primarily the anterotalofibular ligament). An eversion stress to the foot or ankle will tear the medial structures (deltoid ligament), and ankle dorsiflexion with external rotation will lead to a syndesmotic injury [6,8].

Ligamentous injuries are categorized into three gradations:

Grade I is a partial tear without laxity and only mild edema.

Grade II is a partial tear with mild laxity and moderate pain, swelling, tenderness, and instability.

Grade III is a complete rupture resulting in considerable swelling, increased pain, significant laxity, and often an unstable joint (Fig. 83.2).

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FIGURE 83.2 Grade III ankle sprain with a complete tear of the anterior talofibular ligament.

Symptoms

Acutely, the injured patient will report pain, swelling, and tenderness over the injured ligaments. Some patients report a “pop” at the time of injury. Initially, they may have difficulty with weight bearing on the injured ankle and with subsequent ambulation. They may report some ecchymosis during the first 24 to 48 hours. There may be sensory symptoms in the sural, superficial peroneal, or deep peroneal nerve’s distribution. Decreased function and range of motion along with instability are reported more often in grade II and grade III injuries.

Physical Examination

Inspection of the ankle will reveal edema and sometimes ecchymosis around the area of injury, depending on the extent of injury. Range of motion of the ankle joint may be limited by associated swelling and pain. Reduced dorsiflexion may predispose the joint to an ankle sprain [9]. Palpation should include the anterior talofibular and calcaneofibular ligaments, syndesmotic area, and medial deltoid ligament. In addition, the examiner should palpate the distal fibula, medial malleolus, base of the fifth metatarsal, cuboid, lateral process of the talus (to assess for a possible snowboarder’s fracture), and epiphyseal areas to assess for any potential fractures [10,11]. The patient should be examined for strength deficits, or reflex abnormalities, which could reveal concurrent injury. Although it is uncommon, ankle inversion injuries are sometimes associated with peroneal nerve injury and may result in sensory changes on the dorsum of the foot (superficial peroneal nerve) or the first web space (deep peroneal nerve). Deep peroneal nerve injury could result in decreased strength in dorsiflexion and eversion. If a fracture is not suspected, single-leg balance could be tested to assess the extent of proprioceptive compromise.

Ankle stability should be examined through a variety of tests and compared with the noninjured side to assess the amount of abnormal translation in the joint. The anterior drawer test of the ankle will assess the integrity of the anterior talofibular ligament. It is performed by plantar flexing the ankle to approximately 30 degrees and applying an anterior force to the calcaneus while stabilizing the tibia with the other hand. Increased translation compared with the other side implies injury to the anterior talofibular ligament. Studies in cadavers suggest that the test is accurate in detecting abnormal lateral ankle motion, with 100% sensitivity and 75% specificity [12,13]. The talar tilt test (Fig. 83.3) is performed with the ankle in a neutral position and assesses the integrity of the calcaneofibular ligament [13]. The squeeze test (Fig. 83.4) is used to diagnose a syndesmotic injury. It is performed by squeezing the proximal fibula and tibia at the midcalf and causes pain over the syndesmotic area. Similarly, the external rotation stress test is performed by placing the ankle in a neutral position and externally rotating the tibia, leading to pain in the syndesmotic region [14]. Unfortunately, several studies have demonstrated poor correlation between clinical stress test results and the degree of ligamentous disruption [15].

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FIGURE 83.3 The talar tilt (inversion stress) test of the ankle.
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FIGURE 83.4 The squeeze test detects tears of the syndesmosis. The test result is positive when squeezing of the midcalf produces pain in the distal interosseous membrane and syndesmosis.

Functional Limitations

The patient may have difficulty in walking secondary to pain and swelling. Proprioception and balance on the injured ankle will be abnormal as noted by greater difficulty with single-leg standing on the injured leg [16]. The athlete will have difficulty with return to play until swelling and pain have diminished and rehabilitation is nearly completed. Incomplete recovery or inadequate rehabilitation may predispose the patient to reinjury [17

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