There are three ligaments that anchor the lateral aspect of the ankle: the anterior talofibular ligament, the peroneal heel ligament and the posterior talofibular ligament. The anterior talofibular ligament is the first to rupture in an ankle sprain, and it is only after this ligament ruptures that the peroneal heel ligament separates. If the anterior talofibular ligament is ruptured, it is important to check for a concomitant rupture of the lateral peroneal heel ligament: in 64% of cases the anterior talofibular ligament is injured alone, and in 17% there is a concomitant injury to the lateral peroneal heel ligament. The posterior talofibular ligament is rarely ruptured. Ligamentous laxity is associated with a greater extent of talofibular entropion, which is often more likely to occur. Weakness of the peroneal tendon is occasional and may be associated with disc disease. Forefoot valgus causes the forefoot to valgus during the stride cycle, resulting in compensatory inversion of the subtalar joint, which is another factor in the development of ankle sprains. Certain individuals have a genetic predisposition to develop inversion of the subtalar joint, which is also a factor in ankle sprains. Signs, Symptoms, and Diagnosis A structural and functional examination of the foot is performed to rule out the various factors described above. Local anatomic examination by simple palpation of the lateral ankle ligament can identify the site of ligamentous injury. Ankle sprains are graded clinically based on symptoms of soft tissue injury.The Drawer sign is helpful in determining whether the anterior talofibular ligament, which prevents the talus from subluxing anteriorly to the tibia, has been ruptured, and when ruptured the talus is likely to be displaced anteriorly. The method is to let the patient sit at the table with both legs down, the examiner grasps the front of the patient’s lower calf with the left hand, holds the heel with the right hand from behind, and moves the talus forward with force to see if it can be displaced. Under stress x-rays of the ankle are helpful in determining the extent of the ligamentous injury and require a mortise-and-tenon x-ray of the ankle, i.e., an anteroposterior view taken with 15° of internal rotation. Both ankles are maximally internally rotated (local anesthesia is required), and the angle of the lateral tilt of the talus is noted; if the tilts of the talus differ by more than 5°, an impairment of function should be considered; if the difference is greater than 10°, a significant increase in symptoms is often diagnosed as ankle instability. MRI can show whether the ankle collateral ligaments are intact and is used in patients with allergies to arthrographic agents. Arthrography of the ankle is helpful in determining the correct site and extent of ligamentous injury and is only required when surgical repair of a torn ligament is contemplated. And it must be done within the first few days of trauma to be useful; delaying the imaging is of no value. TREATMENT These patients require orthotics to prophylactically control their hindfoot movement. Different measures are taken depending on the grading of the ankle sprain (Table 60-1). Surgery is rarely required because the severe rupture of the ligament makes surgical repair difficult. Some surgeons suggest that isolated ruptures of the anterior talofibular ligament can be immobilized in a cast but should still be repaired surgically if the peroneal heel ligament is torn. Complications The meniscus-like tubercle is a small nodule of the anterior talofibular ligament. Impact of this synovial-lined capsular ligament between the ankle and the talus causes a second- or third-degree injury to the ligament, resulting in persistent synovitis and sometimes fibrotic degenerative swelling with a permanent hard knot. At this point immobilization has no effect and injections of a mixture of insoluble and soluble corticosteroids and local anesthetics between the talus and the outer ankle carries with it a marked and long-lasting improvement that rarely requires surgical intervention. Dorsal median cutaneous nerve This neuralgia is a sensory branch of the superficial peroneal nerve that crosses over the anterior talofibular ligament and is often damaged by ankle inversion sprains. Tapping the nerve frequently causes Tinel’s sign. Blocking local anesthesia is often an effective treatment. Peroneal tenosynovitis Chronic swelling below the outer ankle due to peroneal tenosynovitis is the result of painful sprains caused by ankle inversion during walking, which is compensated for by chronic outward rotation of the lower talonavicular joint. In some cases, dislocation of the peroneal tendon produced by severe ankle sprains can also cause swelling and tenderness. Reflex atrophy after Sudeck trauma Painful swelling of the foot combined with mottled osteoporosis can be secondary to vasospasm from ankle sprains. It needs to be differentiated from edema due to ligamentous injury.Sudeck atrophy is characterized by pain that is out of proportion to what is seen on clinical examination. Multiple tender points moving from one site to another, wandering, and changes in skin moisture or color are characteristic. Tarsal Sinus Syndrome A persistent pain in the tarsal sinus following an ankle sprain with an unclear pathogenesis and possible partial rupture of the intertrochanteric ligament of the talocalcaneal bone or the main trunk of the subtalar cruciate ligament. The normal tarsal sinus is tender, so both ankles are examined for comparison. Because of the tenderness of the anterior talofibular ligament near the tarsal sinus, persistent pain over the anterior talofibular joint tenon is often misdiagnosed as a tarsal sinus tumor. Treatment is an infiltrative injection of 0. 25 ml of fluoxyhydroxyprednisone (40 mg/ml) with 1 ml of 2% lidocaine containing 1:100,000 epinephrine into the tarsal sinus.