DISLOCATIONS AT THE ANKLE-JOINT.
The lower end of the shin and clasp bones to gether form a sort of arch which embraces the surface of the bone of the foot called astragalus or ankle-bone (Fig. 27, p. 64). The tibia on the inside and the fibula on the outside have projecting processes, the internal and external malleoli, which grasp the ankle-bone, so as to prevent any movement from side to side and limit it to a to-and-fro motion. The articular surfaces are further held in apposition by a ligament on each side, and one behind and in front. It will be readily seen, therefore, that the foot cannot be displaced from the leg to one side or other without breaking off one of the malleoli. In dislocation outwards part of the clasp-bone is broken off, producing the fracture known as Pott's which has been already de scribed (p. 95); and in dislocation inwards a similar fracture of the shin-bone occurs. The latter is more serious because the force produc ing it requires to be greater. Both of them require to be treated as fractures.
Dislocation backwards is produced by jumping from a carriage in motion, or by a force which acts similarly by fixing the foot while the leg bones are pushed forwards.
Signs.—The foot being pushed back the leg hones are jerked forwards, and the distance between them and the toes is diminished, so that the back of the foot is shortened, and the heel lengthened. The toes ape pointed down, the heel up. Forward dislocation is almost never seen. The signs would be the reverse of those of backward displacement.
Lastly, a form of dislocation exists in which the two hones are widely separated and the ankle-bone forced up between. It is accom panied by very great injury.
Treatment.--All these dislocations are re duced by pulling on the foot, the leg- bones being fixed, combined with proper manipula tion. Afterwards a splint would be applied, preferably of sonic material easily softened by heat, so that it might be carefully moulded to the joint. This, well padded, would be so fixed as to permit of hot or cold applications being applied to keep down the inflammation, almost certain to occur in so severe an injury.
But the greatest difficulty in such cases, where the damage to the structures about the joint is so great, is to restore freedom of movement to the joint. It is impossible for repair of the soft parts around the joint to take place without adhesions forming, and tendons and ligaments being matted together, more or less, according to the amount of injury. These adhesions limit the joint movements and sometimes prevent them altogether. It would, therefore, as a rule, be necessary to remove the splints comparatively early, and gently to move the joint by manipula tion, to break down the adhesions, while they are still soft: so that, after all risk of inflamma tion has passed away, it would be better to substitute a splint that can be easily removed and re-applied, to permit daily manipulation and massage. Sometimes it is necessary to give chloroform in order to break down the adhesions, and afterwards by manipulation to keep them from re-forming. At what time after the injury this should be done requires experienced judgment to decide, so that medical advice "ought to be obtained whenever possible.