The _fibula_ may be absent completely or in part. The clinical appearances depend upon the condition of the tibia. When the tibia is normal, the most notable feature is the absence of the lateral malleolus, and the extreme valgus attitude of the foot. More commonly the tibia makes a sharp forward bend just below its middle, and the overlying skin presents a dimple or scar-like depression. This has usually been regarded as an evidence of intra-uterine fracture, but the observations of Hoffa suggest that both the bend of the bone and the depression on the skin are due to pressure exercised upon the leg from without by an amniotic band or adhesion. The leg fails to grow, the deformity becomes more pronounced, and the toes become pointed. If the tibia is markedly bent, it may be straightened by osteotomy; and the tendons, Achillis and peronei, may require to be lengthened. If the ankle is unstable as a result of the absence of the lateral malleolus, it may be artificially ankylosed, or the lower end of the tibia may be split vertically so as to make a socket for the talus. In either case, the foot is placed in the equinus attitude to compensate for the shortening of the leg. Deficiency of the tibia is frequently associated with imperfect development of the great toe; deficiency of the fibula with absence of the lateral toes and their metatarsal bones. _Volkmann's Supra-malleolar Deformity._--This condition, which is closely allied to that just described, consists in a congenital deficiency in the development of the bones of the leg, and especially of the fibula, as a result of which the articular surface is oblique and the foot deviates to one or other side. The foot usually occupies a valgus position, the sole looking laterally, and only its medial border coming into contact with the ground. It is treated by supra-malleolar osteotomy. THE FOOT Various deformities are met with in the region of the ankle and tarsus. The term "talipes" is commonly used to include all these, but here it will be restricted to that form in which the heel is more or less elevated, and the foot supinated so that it rests on its lateral border--_talipes equino-varus_. In _pes equinus_ the foot is in the position of plantar-flexion, and the patient walks on the toes. In _pes calcaneus_ the foot is dorsiflexed so that the tip of the heel comes in contact with the ground; this deformity may be combined with eversion of the foot, _pes calcaneo-valgus_, or with inversion, _pes calcaneo-varus_. When the instep is unduly arched, the terms _pes cavus_, _pes arcuatus_ or _hollow claw-foot_ are employed; while loss of the arch constitutes _flat-foot_, and eversion of the sole, _pes valgus_. CLUB-FOOT #Talipes Equino-varus.#--This deformity may be congenital or acquired.