Siffert, Forster, and Nachamie triple arthrodesis for severe cavus deformity. A, Wedge of bone to be removed by osteotomy. Superior part of talar head is retained to form “beak.” Bone to be resected from region of midtarsal and subtalar joints is indicated by colored areas. Dorsal cortex of navicular is included. B, Soft-tissue structures anterior to ankle joint are left undisturbed. C, Final position of foot; forefoot has been displaced plantarward, and navicular has been locked beneath remaining part of talar head. SEE TECHNIQUE 87.18.