Tibialis spastic varus foot caused by osteoid osteoma of the calcaneus.

Tibialis spastic varus foot is an extremely rare condition. A 30-year-old man had tibialis spastic varus foot caused by juxtaarticular osteoid osteoma of the calcaneus. The correct diagnosis was delayed because the symptoms were similar to arthritis and the nidus was difficult to detect on plain radiographs. Curettage of the tumor was done, and the osseous defect was filled with interporous hydroxyapatite. The pain was relieved immediately after surgery. The varus deformity of the foot and spasm of the tibialis anterior muscle gradually improved. Three years 10 months after surgery, the patient was pain-free and the spasm of the tibialis anterior muscle had disappeared. The varus deformity and motion of the foot improved, but a restricted range of motion remained. To the authors' knowledge, there have been no published descriptions of tibialis spastic varus foot caused by juxtaarticular osteoid osteoma of the calcaneus.