In well-marked cases it is necessary to lengthen the shortened structures, and especially the tendo Achillis. When the equinus is corrected, the excessive arching of the foot (pes cavus) and the clawing of the toes usually disappear, but it may be necessary to lengthen the flexor tendons, especially that of the great toe, and also the plantar fascia. Jones divides the tendo Achillis and the flexors of the toes subcutaneously, and maintains the dorsiflexion by excising an oval flap of skin from the front of the ankle. In aggravated cases, the bones must be attacked, for example by excising the talus. Arthrodesis of the ankle alone or along with the mid-tarsal joint may be indicated when these joints are flail-like. Amputation is reserved for cases which are otherwise hopeless, such as that shown in Fig. 147. When the deformity is compensatory to shortening of the limb, it is usually said to be a mistake to correct the equinus. Experience shows, however, that in young patients growth is stimulated by walking on the limb after the deformity has been corrected; the sole of the boot is then raised to the necessary extent. #Pes Calcaneus.#--In this deformity the foot is dorsiflexed at the ankle-joint. It is sometimes combined with eversion of the foot--_pes calcaneo-valgus_, or with inversion--_pes calcaneo-varus_. Pes calcaneus may be congenital or acquired. In the _congenital form_ the deformity is frequently bilateral. There is dorsiflexion at the ankle-joint, and if an attempt is made to flex the foot towards the sole, the extensor tendons stand out prominently. In marked cases the long axis of the calcaneus is vertical, the tendo Achillis lies in close contact with the tibia, and the hollows on either side of the tendon are absent. The peronei are displaced from their grooves, and may lie in front of the lateral malleolus. Corrective manipulations are commenced within a few days after birth, and a malleable splint is worn between times. When the child begins to walk there is a natural tendency towards recovery. In severe cases it may be necessary to lengthen the contracted tendons--the extensor digitorum, the extensor hallucis, and, it may be also, the peroneus tertius and tibialis anterior; the tendo Achillis may require to be shortened.