The signs of displacement backwards or for wards are equally marked. When it is back ward, the shin-bone forms a projection in the ham, while the lower end of the hip-bone is very prominent in front, with a deep hollow below; when it is forward, the swelling in the ham is due to the condyles of the thigh-bone, that in front is owing to the head of the tibia, and the deep hollow is above the tibia. The leg is in both cases shortened. Besides these signs there are others due to the injury done to the soft parts round the joint. In particular the blood-vessels at the back of the joint may be severely pressed upon or injured, so severely sometimes as to arrest the circulation below the seat of injury and produce mortification of the limb. Nerves also may be harmed and numb ness result.
Treatment.—For partial dislocations pulling from the ankle, combined with direct pressure on the head of the bone, is generally sufficient to return it to its place. For complete disloca tion extension must also be practised from the ankle, the thigh-bone being fixed, and pressure being exerted on the head of the tibia in a downward, and on the condyles of the thigh bone in an upward, direction. Great care most afterwards be taken of the joint. It should be fixed and kept quiet for several weeks by means of a splint, or by being laid in a long box care fully padded, and, to allay inflammation, an ice-bag should be applied over the joint, flannel intervening between the skin and the bag.
After recovery a firm bandage or elastic knee cap should be worn.
Displacement of the Cartilages of the —The half-moon shaped pieces of cartilages interposed between the thigh and leg bones sometimes become displaced. This accident generally happens after the cartilages have been affected by inflammation of the joint, a trifling cause, such as a slight twist of the foot when walking, being then sufficient to produce it.
The Signs are sudden and severe pain in the joint, which the patient cannot straighten. In a short time swelling and inflammation occur.
Treatment.—The patient having been laid on his back, grasp the limb in one hand, sup porting it with the other hand in the hollow behind the joint, bend the knee to its utmost, and then suddenly straighten it, twisting the leg slightly backwards and forwards. If this is successful the patient has the use of the joint restored at once. It sometimes entirely fails, and the only remedy is to give support to the joint by a knee-cap. Sometimes a sudden accidental movement replaces the cartilage, after manipulation has failed.
Dislocation of the The head of the fibula lies just below the knee on the outside of the leg, and displacement can be readily made out.
The Treatment consists in strongly bending the knee, and pushing the bone back into posi tion with the fingers. A pad should afterwards be placed over the head of the Lone and secured by a bandage. This should be retained for two months.