In neither variety is there any mechanical obstacle to movement at the ankle-joint.
The treatment is carried out on the same lines as for dislocation of the talus, reduction being effected without difficulty in most cases. If this fails, as it occasionally does, it may be necessary to excise the talus.
Mid-tarsal or transverse tarsal dislocation—that is, at the talo-navicular and calcaneo-cuboid articulations—is extremely rare. The distal segment of the foot is usually displaced towards the sole; the foot is foreshortened, the malleoli raised from the sole, the arch of the foot is lost, and the first row of tarsal bones projects on the dorsum. The treatment consists in reducing the displacement by manipulation, after which massage and movement are employed.
Tarso-metatarsal Dislocations.—One, several, or all of the metatarsals may be separated from the distal row of tarsal bones—the usual cause being a fall from a horse, the foot being fixed in the stirrup. The bases of the metatarsal bones are displaced laterally and towards the dorsum. The base of the second metatarsal and the first cuneiform are sometimes fractured. Reduction by manipulation is generally easy in dorsal dislocations, but may be difficult when the bones are displaced laterally. This may be due to fragments of bone or soft parts getting between the bones, and may necessitate operative interference. In old-standing dislocations, operation is to be advised only when locomotion is seriously interfered with.
Dislocation of the Toes.—The great toe may be dislocated at its metatarso-phalangeal joint, the base of the proximal phalanx passing towards the dorsum ([Fig. 102]). Diagnosis and reduction are alike easy.
Fig. 102.—Radiogram of Dislocation of Toes.
(Sir Montagu Cotterill's case.)
Inter-phalangeal dislocations are rare and are easily reduced.