Etiology. — The causes are usually malnutrition, weakness, or rickets, and the affection is often precipitated by some affection of the foot.
For all cases of genu valgum requiring osteotomy it is better surgery to operate upon the tibia, and not the lower end of the femur. In the majority of cases of knock-knee sciagraphs will show that the essential condition is a curve out ward in the bones of the leg, and not an elongation of the internal condyle or outward curve of the lower end of the femur. C. A. Morton (Brit. Mcd. Jour., Nov. 15, TS).
Thus when rickets plays a prominent part we find the disease occurring in childhood. When weakness acts as a cause we find it occurring in adolescents somewhat in the same manner as does lateral curvature or flat-foot, but earlier than these two affections. It is often as sociated with flat-feet, and it can readily be seen how the letting down of the arch of the foot tends to throw the knees in ward. This influence, continuing for a long time, at last makes itself evident on the structure of the joint. A condi tion of valgus occurring from trauma tism or other cause as paralysis may cause the development of knock-knee, but if there is no constitutional weakness these affections may exist without giving rise to any knee-troubles.
Symptoms.—If the condition is once suspected and looked for, there is usually no difficulty in diagnosing it, but it is liable to be overlooked. Attention is apt to be first attracted by either the child's stumbling and falling or else by its awk ward gait. In very young children they will begin to stumble and fall frequently or acquire a sort of waddling gait, and this after they have been walking natu rally for some time. If on examination flat-feet are found, these may be sub jected to treatment and the knees' con dition be entirely overlooked.
Prognosis.—Knock-knees is not so apt to improve with growth as will bow-legs, neither does it respond so readily to treatment. On this account operative measures are more early resorted to.
Treatment. — The general constitu tional condition of the patient should be attended to and remedies—such as cod liver-oil and syrup of the hypophosphites —given. Hygienic and dietetic meas ures are also important. Considerable can often be accomplished by mechanical means, particularly in children under the age of six years, when the deformity is not too pronounced.
The form of apparatus usually em ployed consists of a waist-band to which are fastened two leg-irons: one going down on the outside of each leg and fastened to the shoe with a joint at the ankle. The knees are pulled outward toward the leg-irons by straps. Some times joints are introduced at the knees. When this is desired greater stability and efficiency is insured by having irons up each side of the leg instead of only the outer. A pad is placed on the inside of the knee and the braces are straightened, with wrenches from time to time as necessity requires. It is necessary that the leg-irons be firmly fastened to the shoe and that the shoe itself be strength ened so as to guard against an increase in the tendency to valgus.
When the deformity is marked or the parents are unable to give the case the attention which treatment by means of apparatus entails, then resort may be had to operative means.
The operation employed is division of the bone, or osteotomy. Macewen in serts the osteotome on the inner side about a finger's breadth above the tubercle for the adductor-magnus mus cle. The division is effected from within outward. The knee should be bent, as the artery is farther away from the hone in that position. Some make an incision through the skin through which the osteotome is introduced; this is not necessary. A better way is to place the edge of the osteotome on the skin at the desired spot and then by a gentle rock ing motion cut through the skin. A fter completion of the operation a large dressing of gauze is applied, but no sutures need to be inserted. The legs are put up in a somewhat overcorrected position, either in plaster of Paris, which is best, or splints. Hahn advocated di vision of the bone on the outer side, and I much prefer it, because the bone is divided on the concave side instead of the convex, thus leaving a bridge of bent bone and periosteum to prevent undue displacement of the fragments, besides being easier of performance. The oper ation of Macewen, however, from the inner side is the one usually recom mended. Cuneiform osteotomy with the removal of a wedge of bone is never done for this affection.