How To Diagnose Lateral Ankle Injuries

By Remy Ardizzone, DPM, and Ronald L. Valmassy, DPM

   The initial presentation of an acute lateral ankle injury may be deceptive. What appears to be a simple ankle sprain may represent a fracture of the ankle or hindfoot. A tendon or impingement-type injury may not present until later in the healing process. One may not be able to appreciate other intraarticular injuries without advanced imaging studies. Nerve injuries may offer the greatest diagnostic challenges of all (see “A Guide To Differential Diagnosis Of Inversion Ankle Injuries” below).

   The ankle is the most common joint injured in sports and ankle sprains represent 85 percent of all ankle injuries in the United States.1-5 When approaching any lateral ankle injury, it is important to ascertain whether it represents an acute or overuse injury.

   When evaluating an acute injury, it is important to perform a thorough physical examination and rule out the possibility of fracture. Swelling and ecchymosis may not correlate to the location of injury. Standard ankle series radiographs, including anterior-posterior, oblique and lateral views, will provide evidence of fracture to the lateral malleolus, posterior and lateral talar processes, and anterior processes of the calcaneus. If physical examination findings warrant, obtaining additional radiographs of the foot may be necessary to rule out fracture to the fifth metatarsal base as well.

   While an inversion ankle injury commonly leads to injury to the lateral collateral ankle ligaments, many other structures in this area may also be injured.1,6-8 One may not appreciate these associated injuries until weeks or months after the initial event. Other associated lateral ankle injuries do not manifest themselves until the patient attempts to return to full activities but is unable to do so due to persistent lateral ankle pain. Typical associated injuries include chronic lateral ankle instability, injury to the peroneal tendons, nerve injury or intraarticular injury.

Weighing The Etiology And Impact Of Chronic Lateral Ankle Instability

   Following an inversion ankle sprain and particularly following repeated inversion ankle sprains, there is a risk of developing chronic lateral ankle instability due to repeated stretching or tearing of the lateral collateral ankle ligaments.

   The lateral collateral ankle ligaments consist of the anterior talofibular ligament, the calcaneofibular ligament and the posterior talofibular ligament. Typically, an inversion ankle sprain results in injury to either the anterior talofibular ligament or calcaneofibular ligaments.9 Frequently, both of these ligaments will be injured to some degree.1 Given its location deep to the peroneal tendons in the posterior ankle, the posterior talofibular ligament rarely sustains significant injury.3 By contrast, the anterior talofibular ligament is the most frequently injured ligament in the lateral ankle. It is also the only one of these three ligaments that is intracapsular.6

   Injuries to the lateral collateral ligaments are typically classified as grade 1, 2 or 3.10 Grade 1 injuries are characterized by stretching or inflammation of one or more of the ligaments. Grade 2 injuries, which are most common, consist of partial tearing of one or more of the ligaments. Grade 3 injuries involve complete rupture of one or more of the ligaments. Early reduction of swelling and prompt initiation of physical therapy are key to regaining full function and stability.1 Outcome studies of grade 3 injuries have shown little difference between conservative and surgical treatment in terms of stability, strength and one’s ability to return to full activities.11

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