Abstract
Ankle sprains are a common cause of morbidity in the general and athletic population. The majority of sprains involve the lateral aspect of the ankle, affecting the anterior talofibular ligament. However, the extent of injury will depend upon the mechanism of injury. Acutely, the injured athlete will report pain, swelling, and tenderness over the injured ligaments with compromised proprioception. Use of the Ottawa ankle rules will help assess the need for initial imaging. Fortunately, most ankle sprains respond to conservative treatment utilizing activity modification, modalities, and therapeutic exercises. Return to activity will depend upon the extent of injury.
Keywords
Ankle, Injury, Sprain
| Synonym | |
| |
| 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. Between the ages of 15 and 24 years, ankle sprains are slightly more likely to occur in males than females (incidence ratio of 1.04) and nine times more likely to occur in younger than older individuals. However, a recent meta-analysis showed that overall, females have a higher incidence than males (13.6 vs. 6.94 per 1000 exposures). 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. 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.
Eighty-five percent of all ankle sprains occur on the lateral aspect of the ankle, involving the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) ( Fig. 83.1 ). 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, as they may have a prolonged recovery compared to 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 quite resistant to tearing. Most ankle sprains will recover during several weeks to months, depending upon the grade of injury. It is estimated that 20% to 40% of ankle sprains result in chronic sequelae. An ankle sprain that does not heal may be caused by injuries to other structures and will necessitate further investigation for other causes.
The exact structure torn will depend upon 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 ATFL). 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.
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 ).
FIG. 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 weight bearing on the injured ankle and with subsequent ambulation. They may report some ecchymosis over the first 24 to 48 hours. There may be sensory symptoms in the sural, superficial, 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 upon 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. Palpation should include the ATFL and CFLs, syndesmotic area, and medial deltoid ligament. In addition, the examiner should palpate the distal fibula, medial malleolus, base of the fifth metatarsal, cuboid, and lateral process of the talus (to assess for a possible snowboarder’s fracture), and epiphyseal areas to assess for any potential fractures. The patient should be examined for strength deficits or reflex abnormalities, which could reveal concurrent injury. Although 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 non-injured side to assess the amount of abnormal translation in the joint. The anterior drawer test of the ankle ( Fig. 83.3 ) will assess the integrity of the ATFL. 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 ATFL. Studies in cadavers suggest the test is quite accurate in detecting abnormal lateral ankle motion with 100% sensitivity and 75% specificity. The talar tilt test ( Fig. 83.4 ) is performed with the ankle a neutral position and assesses the integrity of the CFL. The squeeze test ( Fig. 83.5 ) 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. Unfortunately, several studies have demonstrated poor correlation between clinical stress test results and the degree of ligamentous disruption.
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. 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. Of note, the single-leg balance test can be helpful in predicting which athletes may sustain an ankle injury over the course of the upcoming season. Chronic ankle sprains can result in mechanical instability, with objective instability or laxity noted on examination in all patients.
Diagnostic Studies
Standard anteroposterior, mortise ( Fig. 83.6 ), and lateral radiographs should be considered in cases in which there is tenderness over the lateral malleolus, ankle joint, syndesmosis, or other bony structure to rule out an underlying fracture. The Ottawa ankle rules ( Fig. 83.7 ) were developed and validated to clarify the indications for these ankle radiographs. The rules recommend imaging when there is tenderness along the lower 6 cm posterior edge or top of the lateral or medial malleolus, the navicular, the base of the fifth metatarsal, and an inability to bear weight immediately post injury and in the emergency room. Adherence to these rules has shown a 30% reduction in x-ray utilization while missing no major fractures. At 4 to 6 weeks, a slowly healing lateral ankle injury without significant pain resolution or improvement should be evaluated radiographically, especially if an initial radiograph was not obtained.
