Tuberculosis of the foot and ankle.

Tuberculosis of the foot and ankle is an uncommon presentation of skeletal tuberculosis. The uncommon site, lack of awareness, and ability to mimic other disorders clinically and on radiographs, leads to diagnostic and therapeutic delays. In the early stages and when the disease is limited to bone, medical treatment leads to excellent healing and limited residual disabilities. Joint involvement occurs because of spread from a periarticular bony focus, and in the midfoot, the disease may spread to involve all the interconnected joints, leading to a stiff foot and residual deformities. Of 74 cases reviewed, the calcaneus was involved most commonly, followed by infection of the midtarsal, Lisfranc joints, and ankle. The most common radiologic finding is that of osteoporosis, which may be intense: cancellous bone involvement may present as a cystic lesion with or without sequestrum. Computed tomography scans and magnetic resonance imaging are helpful examinations. Because the disease is paucibacillary, a positive acid fast bacilli culture is rare and the diagnosis usually is confirmed by obtaining granulomatous tissue on biopsy. The treatment basically is medical, with surgical intervention being reserved for patients with intractable disease or as a salvage procedure for patients with deformed hindfoot joints.