The meniscus-like tubercle is a small nodule in the anterior talofibular ligament, a synovial-lined joint capsule ligament that is impinged between the outer ankle and the talus, causing a 2nd or 3rd degree injury to the ligament and producing persistent synovitis, sometimes with fibrous degenerative swelling and permanent sclerosis. Immobilization is not useful at this point, and injections of a mixture of insoluble and soluble corticosteroids and local anesthetics between the talus and the outer ankle carry significant and lasting improvement, rarely requiring surgery. Dorsal median cutaneous nerve This neuralgia is a sensory branch of the superficial peroneal nerve that crosses the anterior talofibular ligament and is often damaged by inversion sprains of the ankle. Light percussion often causes Tinel’s sign. Blocking local anesthesia is often an effective treatment. Peroneal tenosynovitis Chronic swelling below the outer ankle caused by peroneal tenosynovitis is the result of a painful sprain caused by inversion of the ankle during walking, which is compensated for by chronic valgus rotation of the lower talofibular joint. In some cases, subluxation of the peroneal tendon produced by a severe ankle sprain can also cause swelling and pressure pain. Sudeck post-traumatic reflex atrophy Painful swelling of the foot combined with patchy osteoporosis can be secondary to vasospasm caused by ankle sprain. Sudeck atrophy is characterized by pain that is disproportionate to what is seen on clinical examination. Multiple tenderness points moving from one site to another, wandering, and changes in skin moisture or color are characteristic signs. Tarsal sinus syndrome Refers to persistent pain in the tarsal sinus following an ankle sprain. The pathogenesis is unclear, and there may be a partial rupture of the intertrochanteric ligament or the main stem of the inferior cruciate ligament of the talus. There is pressure pain in the normal tarsal sinus, so both sides of the ankle are examined for comparison. Because of the pressure pain in the anterior talofibular ligament near the tarsal sinus, persistent pain over the anterior talofibular joint mortise is often misdiagnosed as a tarsal sinus tumor. Treatment is an infiltration injection of 0.25 ml of fludrocortisone (40 mg/ml) with 1 ml of 2% lidocaine containing 1:100,000 epinephrine into the tarsal sinus.