Coxa Plana

Degenerative changes, similar to those observed in coxa plana, often occur in the course of treatment of congenital dislocation of the hip, slipping of the upper femoral epiphysis, or fracture of the neck of the femur. These changes are due to interference with the circulation to the head, either by "wringing out" of the blood vessels along the neck by immobilization in full extension, often with abduction and internal rotation, or by the separation of the head from the neck by injury or during the course of treatment. These degenerative changes can be prevented by the avoidance of immobilization in a position of tension, and by not separating the head from the neck in the course of treatment. Similar degenerative changes occur in suppurative arthritis of the hip, due to the inflammatory and mechanical pressure interference with the circulation to the femoral head. This damage can be prevented or reduced by very early adequate drainage, when there is pus or fluid under tension in the hip joint. Coxa plana runs a self-limited course over a period of years, and always heals. There is always a residual deformity: The femoral head and neck are broad, the head is flattened and shallow, and the acetabulum is somewhat flattened and shallow to correspond to the head. Treatment has little effect on the course of the disease. Reduced activity and freedom from weight-bearing result in the relief of pain and muscle spasm, with less limitation of motion, but probably have little or no effect on the course of the disease in the femoral head and neck. Bed rest is the treatment of choice in the incipient or acute and rapidly progressive phases of the disease, and the hip should be kept slightly flexed for relaxation of the soft tissues and improvement in circulation. The best ambulatory treatment is the suspension of the extremity from a sling and belt, with the use of crutches. This should be continued while there are pain and spasm and while the head is soft. The drilling operation, when done skillfully and gently, with a minimum of damage to the circulation, results in more rapid healing of the lesion with less deformity, but the period of healing is still much too long. Some better method of treatment should be sought. Coxa plana may sometimes be prevented by early rest of the hip in the incipient stage, or in the stage of synovitis preceding the degenerative changes in the femoral head. More must be learned, however, of the cause and prevention of coxa plana.