_Treatment._--In the acute stage the limb is extended by means of the weight and pulley, and kept at rest with the single or double long splint, or by sand-bags. If there is suppuration, the joint should be aspirated or opened by an anterior incision, and Murphy's plan of filling the joint with formalin-glycerine may be adopted. In children, it is remarkable how completely the joint may recover.
If there is dislocation, the head of the femur should be reduced by manipulation with or without preliminary extension; it has been successful in about one-half of the cases in which it has been attempted. Preliminary tenotomy of the shortened tendons is required in some cases. When reduction by manipulation is impossible, the joint structures should be exposed by operation and the head of the bone replaced in the acetabulum. When the upper end of the femur has disappeared, the neck should be implanted in the acetabulum, and the limb placed in the abducted position.
#Arthritis Deformans.#--This disease is comparatively common at the hip, either as a mon-articular affection or simultaneously with other joints.
[Illustration: FIG. 119.--Arthritis Deformans, showing erosion of cartilage and lipping of articular edge of head of femur.]
_The changes in the joint_ are characteristic of the dry form of the disease, and affect chiefly the cartilage and bone. The atrophy and wearing away of the articular surfaces are accompanied by new formation of cartilage and bone around their margins. The head of the femur may acquire the shape of a helmet, a mushroom, or a limpet shell, and from absorption of the neck the head may come to be sessile at the base of the neck, and to occupy a level considerably below that of the great trochanter (Fig. 120). These changes sometimes extend to the upper part of the shaft, and result in curving of the shaft and neck, suggesting a resemblance to a point of interrogation (Fig. 121). The acetabulum may "wander" backwards and upwards, as in tuberculous disease. It is usually deepened, and its floor projects on the pelvic aspect; its margins may form a projecting collar which overhangs the neck of the femur, or grasps it, so that even in the macerated condition the head is imprisoned in the socket and the joint locked. There is eburnation of the articular surfaces in those areas most exposed to friction and pressure.