Resection of a wedge from the tarsus (Davies Colley, 1876) is reserved for the most severe cases in which the shape and rigidity of the bones prevent correction of the deformity by any other means. The base of the wedge is on the lateral aspect, and the bone removed includes parts of the calcaneus, cuboid, talus, and navicular.
Removal of the talus is an alternative operation to resection of the tarsus, and may yield equally good results.
In children, before the tarsal bones have become completely ossified, Ogston's method yields good results; instead of removing a wedge from the tarsus, the osseous nucleus of each bone is gouged out, leaving the cartilaginous shell. In this way the intertarsal joints are not interfered with, and the cartilaginous tarsus can be moulded so that when ossification is completed the bones differ but little from the normal.
After any of these operative procedures, manipulations, massage, exercises, electrical stimulation of the muscles, and the wearing of some apparatus must be persevered with for at least twelve months. Failures are due to not sufficiently over-correcting the deformity in the first instance, and to neglect of after-treatment; in hospital practice it is difficult to ensure continuous supervision over long periods.
Finally, amputation may be called for when other methods have failed, and the patient is unable to put the foot to the ground because of suppurating bursæ and ulceration of the skin.
Acquired Talipes Equino-varus.—In the great majority of cases this condition results from anterior poliomyelitis. It especially affects the peronei and the extensors of the toes, and is unilateral. The patient is unable to dorsiflex and abduct the foot, which hangs with the toes pointed and the sole turned medially.
At first the joints are flaccid, and the attitude can easily be corrected by manipulation. In course of time, however, the opposing muscles—those inserted into the tendo Achillis, the tibialis posterior, and the long flexors of the toes—become shortened, and there is secondary contraction of the plantar fascia and of the ligaments on the medial side of the foot, and the deformity is thus rendered permanent. The bones also are altered in their shape and mutual relations, the talus being rotated forwards so that a large portion of its trochlear surface protrudes from the tibio-fibular socket. The skin is cold and livid, and readily suffers from pressure sores. The whole limb is ill-developed, and may be shorter than its fellow, and the paralysed muscles are wasted and exhibit for a time the reaction of degeneration.
A similar deformity may result from section of the peroneal (external popliteal) nerve, from the peroneal form of progressive muscular atrophy, and from peripheral neuritis.
The treatment of paralytic equino-varus, short of operation, has been referred to under anterior poliomyelitis ([p. 242]). If tendon transplantation is indicated, the tendon of the tibialis anterior is attached to the cuboid, and a strip of the tendo Achillis to the dorsal aspect of the tarsus. Jones displaces the tibialis anterior into the base of the fifth metatarsal.
If the paralysis is widely distributed, and the joints are flail-like, it is better to ankylose the ankle and mid-tarsal joints. It may be necessary to divide in several places the plantar fascia and other structures that have undergone secondary shortening.