The earlier the operation is done the better. It is necessary to always maintain the limb in a position of well-marked abduction, and for a long time, nor can patients be released from this at the expiration of the first dressing period, usually twelve to fifteen weeks, although the abduction can usually be reduced with each dressing until at last the limbs are permitted to come together after the expiration of nine to eighteen months. Even after the lapse of this length of time it may be necessary to provide some form of apparatus by which too much rotation in either direction may be prevented, or by which pressure may still be made over the trochanter, in order that it may be kept constantly pushed into the acetabulum ([Figs. 271] and [272]).
Fig. 272
Unilateral congenital dislocation, showing the fixation bandage. A shoe with a cork sole about two inches in height should be worn on the operated side, while the attitude of exaggerated abduction is maintained. (Whitman.)
Fig. 273
Coxa valga, with defective development of the right femur. (Albert.)
COXA VARA AND VALGA.
This term is applied to an abnormality in the shape of the neck of the femur, consisting of a downward curvature or bending of the femoral neck, which is thus displaced until it stands almost at a right angle with the shaft instead of at the normal obtuse angle. At the same time there is often posterior curvature, or sometimes an anterior curve, of the neck, which causes a corresponding rotation of the axis of the whole limb. The pelvic side of the hip-joint is unaffected, the change occurring usually solely in the upper end of the femur, the joint not being involved. It may appear in congenital form and then may be attributed either to intra-uterine pressure or to antenatal rickets or osteomalacia. The acquired form is usually due to a non-inflammatory softening, or to structural changes which permit of yielding, as above described. Doubtless different cases have different causes, and they are not to be included in one brief sentence. The condition corresponds to those abnormalities at the knee which produce knock-knee and bow-leg. Were the bone as easily examined at the upper end of the femur as at the knee the condition would be more easily recognized. Therefore the term has reference not so much to the results of active disease as to deformities of congenital or acquired character. Fully three-fourths of the cases are met with in male subjects, and the majority of these occur only on one side. Thus of 190 quoted by Whitman, 85 were unilateral, while only 26 occurred in females.
The more nearly the angle of fixation of the neck of the femur approaches a right angle the further above Nélaton’s line will the trochanter appear, and the more conspicuous this change the greater the difficulty in abduction. Moreover, to shortening may be added internal or external rotation, with consequent tilting of the pelvis and compensatory alteration of the spinal curves.