Pure talipes varus is very uncommon. Talipes valgus is the opposite of talipes varus, the foot being everted and raised, so that the patient walks on the inner margin. A pure valgus is not often met with, the condition being generally associated with flat-foot, which is sometimes meant when the term talipes valgus is used. In the usual type of valgus the foot is flat, the arch being lost, and the head of the astragalus and the scaphoid presenting in the sole. Talipes equinus and talipes calcaneus generally are acquired, being due to atrophy and contraction of the muscles of the leg, often secondarily to poliomyelitis. In the former the heel is raised from the ground by contraction of the muscles attached to the tendo Achillis, and the patient walks on the balls of the toes, the foot frequently becoming curved from the transmission of weight and contraction of the plantar fascia, so that heel and toes approach one another (talipes cavus). In the latter, which is less common, the anterior part of the foot is drawn up, and the patient walks on the heel, which is general very prominent, owing to the tilting of the os calcis with projection of its posterior end.
Flat-foot is due to a loss of tone and stretching of the tendons and ligaments of the sole of the foot. In consequence the greater portion of the sole of the foot comes in contact with the ground, the foot tending also to become slightly abducted. In bad cases the osseous arch may sink to such an extent that the head of the astragalus and the tubercle of the scaphoid may present in the sole. The affection is generally painful, the pain being frequently referred to the region of the ankle, and is best treated by attention to the tone of the muscles and ligaments, walking on the balls of the toes, etc. In severe cases a wedge has been removed from the tarsal bones (tarsectomy), and the patient thus given a fixed osseous arch.
The toes are subject to various deformities, especially the great and second toes. Hallux valgus has already been mentioned. Hallux rigidus consists of a fixed flexion of the meta-tarso-phalangeal joint. Hammer toe is a condition which most frequently affects the second toe, that toe being the longest in a classical foot, and so being pressed upon by badly-fitting boots, or by the great toe in hallux valgus. It becomes dorsiflexed at the metatarso-phalangeal joint, flexed at the first interphalangeal joint, and hyperextended at the last interphalangeal joint. A corn frequently develops over the first interphalangeal joint, and another over the tip of the toe, and considerable pain is caused. The tendons and ligaments become contracted in the later stages.
Amputation of the foot may be performed through the tarso-metatarsal joint (Lisfranc), or through the midtarsal joint (Chopart), or at the ankle (Syme). The latter generally yields the most serviceable stump. In Lisfranc1 s amputation a plantar flap is raised by an incision across the bases of the toes, and extending backwards to the bases of the first and fifth metatarsal bones, all the structures down to the bones being included-namely, skin, subcutaneous tissue, abductor minimum digiti, flexor brevis hallucis and minimi digiti, trans versus pedis, and tendons of the flexor longus digitorum and hallucis, tibialis posticus tendinous^expansions, plantar vessels and nerves. The dorsal flap has a convexity forwards, and runs from the base of the first to that of the fifth metatarsal, and also includes the structures down to the bone- namely, skin, fascia with superficial veins and musculocutaneous nerve, tendons of the extensor communis and brevis digitorum, extensor longus hallucis, tibialis anticus, and anterior tibial nerve and dorsalis pedis artery. The articulation between the base of the first metatarsal and the internal cuneiform is then opened, care being taken not to go too far back and open the joint between the internal cuneiform and scaphoid instead. Then the three outer metatarsals are disarticulated from the tarsus. The chief difficulty lies in disarticulating the second metatarsal, the base of which, articulating with the short middle cuneiform, is mortized in between the internal and external cuneiforms. The position of the articulation is sought on the dorsal surface with the point of the knife, the metatarsal being strongly flexed, and once the basal joint is opened the lateral articulations with internal and external cuneiforms are divided, that with the internal cuneiform presenting the strong ligament of Lisfranc. The whole of the metatarsals are now removed, the tendons of the tibialis posticus (expansions) and peroneus longus on the plantar, and peronei brevis and tertius on the dorsal aspect, being cut. The internal cuneiform forms a marked projection, and is difficult to cover unless a very abundant flap has been provided. Hey, instead of disarticulating the first metatarsal, saws through the internal cuneiform at the level of the articulation between middle cuneiform and second metatarsal, while Skey saws across the base of the second metatarsal instead of disarticulating, and Cooper saws across the bases of all the metatarsals, the tendons of the peronei and tibialis anticus being thus left intact, and the large anterior synovial cavity unopened. Chopart's amputation is performed by making a short dorsal flap from behind the tubercle of the scaphoid to a finger's breadth behind the base of thè fifth metatarsal, reaching anteriorly to the bases of the metatarsals ; and a plantar flap, which, commencing and ending at the same points, extends forwards to the centre of the metatarsals, both flaps taking all structures down to the bone, and are as given for Lisfranc, save that the peroneus brevis and peroneus tertius are cut in the dorsal, and flexor accessorius and tibialis posticus are cut in the plantar flaps. Disarticulation is done from within outwards through the astragalo-scaphoid and calcaneo-cuboid joints.
Syme's amputation is performed by taking a point just below and in front of the external malleolus, and a point opposite to it on the inside. These points are joined by a vertical incision made with the foot strongly dorsiflexed, so as to keep behindk the ridge of the posterior tuberosity of the os calcis. The flap is cut down to the bone, and is then dissected up, care being taken to keep close to the bone, and so avoid injury to the vessels. The tendo Achillis may be cut close to its origin or peeled off. The ends of the first incision are now joined across the dorsum, the foot is firmly extended, and disarticulated at the ankle. The malleoli are then sawn off, and the wound closed. The anterior tibial artery is cut in the centre of the anterior incision, the nerve lying to its outer side, and the long saphenous vein to its inner side. The small anterior peroneal artery is also cut on the front of the ankle. The peroneus tertius, extensor hallucis, and tibialis anticus muscles are cut in front. The plantar arteries and nerves are cut on the inner side of the heel flap, and the external saphenous vein and nerve on the outer. The peronei longus and brevis, abductor hallucis, tibialis posticus, flexors longus hallucis, and digitorum are divided in the heel flap. In Pirogoff's amputation the posterior portion of the os calcis is cut off instead of bsing removed, :-md is attached to the cut surface of the tibia.