Abstract Of Article By Drs. Amstutz And Wilson
(The following is an abstract of the article, "Dysgenesis of the Proximal Femur (Coxa Vara) and its Surgical Management", by Drs. Amstutz and Wilson, which is referred to in Dr. Yelton'.s report).
The authors direct their discussion primarily to three groups of congenital coxa vara, although other types, including those associated with general growth disturbance and those acquired as a result of disease or trauma, are mentioned in a detailed classification.
The three prime groups are:
Congenital Short Femur with Coxa Vara
Congenital Bowed Femur with Coxa Vara
Congenital Coxa Vara
A total of forty cases provide the subject matter of the discussion.
A) Congenital Shortening of the Femur with Coxa Vara
Nine cases were in this group, one of which was bilateral. A number had no other abnormalities - the incidence of solitary deformity being greater than had previously been reported. As age increased, the femoral shaft of these patients migrated proximally and posteriorly. With the five adults in the group, limb length discrepancy reached 10 to 15 inches.
The basic treatment (unilateral) is a prosthesis, with surgical intervention restricted to facilitating the use of the prosthesis. An elevated extension shoe is used for children to ages 5-8 years, or even longer. This may be followed by a brace-type prosthesis with the foot in mild equinus and an intrinsic knee joint near the level of the contralateral knee. In this prosthesis, weight-bearing is shared by ischium, thigh and foot. A new prosthesis is usually required every three years during growth and a pelvic belt is sometimes needed to stabilize the hip. The authors appear to have some reservations concerning early Syme amputation to promote better prosthesis fit, although they declare in their summary that "(it) has proved to be most useful".
B) Congenital Bowed Femur with Coxa Vara
This type of deformity occurred in nine cases. The authors note that it is rarely described in the literature. One patient was bilaterally affected, and two had congenital shortening of the contralateral femur. There was the same incidence of associated congenital anomalies as in Group A. The striking characteristic of this group is the lateral subtrochanteric bowing with sclerosis of the medial side of the shaft. The coxa vara is definite, but usually not as severe as in Group A. Eventual shortening is considerable - four to six inches at maturity.
Either a prosthetic device or an elevated shoe is generally prescribed for unilateral cases. Indications for osteotomy are poorly defined as yet, and may be contraindicated, because of possible abnormal tissue development at the hip.
C) Congenital Coxa Vara
This was the largest category studied and involved 17 cases, six of which were bilateral. Sex ratio was nearly equal and no racial predilection was evident. Heredity, familial incidence and trauma were not found to be factors in these patients. No associated congenital anomalies were found in any of the cases - a significant difference from the other two groups. Shortening of the femur is much less marked in these patients, the maximum being 2 inches. Limp and waddle are the presenting complaints, and diagnosis of the condition can usually not be made until the weight-bearing age. Fatigue may develop, but pain is seldom present in children. Lumbar lordosis is excessive. The progress of varus depends on the degree to which ossification is disturbed.
Osteotomy is widely accepted for this group of patients. The core of the problem is not what to do, but when and how. The essential factor here is the extent of the deformity; its severity must be determined in relation to age, and in terms of interference with function. With a limp and a neck shaft angle of 90 degrees or less, surgery is indicated. This is also true where the linear neck defect is vertical, or the child is younger than six years and the varus deformity has progressed. Some surgeons prefer postponing the operation until puberty or later, since recurrence of deformity is common in younger persons. The authors do not subscribe to this point of view if the degree or progression of the deformity is severe. Trans-cervical bone grafting as an adjunct to osteotomy may prevent recurrence of the condition. A caliper ischial weight-bearing brace may be useful if osteotomy must be delayed.