Dysgenesis Metaphysealis Proximalis Femoris
Knud Jansen, M.D.
The etiology, pathology, and terminology of proximal femoral dysplasia have been discussed extensively in several reports1,3,4.
It is generally accepted that the defect is due to a teratogenic lesion, and that it is closely related to congenital coxa vara, congenital pseud-arthrosis, and to humeral angulations. Congenital aplasia of the fibula and the tibia is frequently associated with the condition. All degrees of dysplasias in the hip region, ranging from coxa vara to phocomelia, may be observed.
In the case of proximal aplasia, arthrography may reveal a nonossified femoral head, apparently separated from the diaphysis of the bone (Fig. 1A ).
In some instances autopsy specimens have demonstrated the presence of a cartilaginous femoral head connected to the ossified shaft by fibrous or cartilaginous tissue. If untreated, the dysplasia creates cosmetic and orthotic problems of considerable magnitude (Fig. 1 B ).
Several attempts at surgical restoration in cases of proximal dysplasia have been reported. These attempts include osteotomy, bone-grafting, and release of the flexion contracture1, 3,7. A rotation plasty was recommended by Van Nes10. In this procedure the knee joint, which is situated more or less at hip level, is rotated 180 degrees. The ankle joint may then be used as a knee joint and a below-knee prosthesis fitted.
None of the procedures advocated to date seems to offer a completely satisfactory functional and cosmetic solution to the problem. A Syme's operation may improve the cosmetic appearance of the limb and, if the femoral shaft has some length, a knee arthrodesis facilitates prosthetic fitting and ambulation (Fig. 2 A/B ) .
Treatment by Permanent Traction
Our clinical experience in the management of allied deformities has demonstrated the deforming forces exerted by the tight soft tissue structures. In cases of fibular hypoplasia we may find the lateral malleolus dislocated upwards. Surgical exposure reveals tense fibrous structures at the normal site of the fibula. Release of these tight structures facilitates reduction of the foot dislocation and the correction of the angulation. Based upon these observations, traction has been applied in three cases of proximal metaphyseal dysgenesis in an attempt to correct the deformity,
Case No. 1 was born September 3, 1962, and was the first-born son of a woman who took Hydramnion during the pregnancy. At birth the child's condition was diagnosed as proximal aplasia of the left femur. X-rays taken September 4th revealed that the proximal part of the left femur was absent (Fig. 3 A ).
Extension was applied four months after the birth of the child by means of a Thomas splint made from plastic material. Attachment to the leg was achieved by means of ventfoam, rubber bands, and a cotton bandage. This method of treatment was continued for some years. When, at the age of one year, the boy began to stand and walk, he was supplied with a modified Thomas walking caliper made of a light metal alloy (Fig. 3 B ), and later the traction was applied to a high shoe.
During the following years, the proximal part of the femur appeared in the X-rays and, at the age of three years, a "congenital pseudarthrosis" was the only persisting defect (Fig. 3 C ). In October 1966, a Phemister osteoplasty was performed-an autogenous onlay graft being placed subperiosteally. Solid union was obtained three months later and the bandage was discarded and replaced by an elevated shoe. Some increase in the coxa vara deformity
has recurred since the traction was discontinued (Fig. 3 D ). The difference in length of the two limbs (10.3 cm) has remained constant for the last one and one-half years.
Case No. 2, a female, was born December 2, 1966, and was also a first-born child. Her mother had taken diphenhydramine theocal in the second month of pregnancy because of nausea.
At birth, the right femur was found to be extremely short. X-ray pictures showed proximal femoral aplasia, the proximal part of the visible femur pointing toward the iliac wing. The length of the right femur was 2 cm, that of the left was 7.2 cm. A Thomas splint with skin traction, as described above, was applied 19 days after birth. Recent X-rays (December 11, 1968) showed the nucleus of the femoral head to be in its normal place. The femoral diaphysis is pointing in more of a proximal direction than is normal (Fig. 4 ).
Case No. 3, a male, was born November 30, 1967, and was also a first child. During her pregnancy the mother had taken two tablets of an undetermined type because of nausea. At birth, hypoplasia of the right femur and malposition of the right foot were observed. At examination on February 12, 1968 (two and one-half months after birth), hypoplasia of the right femur was confirmed. Thirty-degree flexion contractures of the right hip and knee were evident. A slight constriction band was present above the malleoli and the right foot was in a valgus position. X-rays showed aplasia of the proximal portion of the right femur with the diaphysis pointing toward the iliac wing. The length of the right femur was 3.8 cm, that of the left was 7.8 cm. The right tibia was slightly hypoplastic, its length being 5.9 cm, as compared to 6.9 cm for the left. The right fibula was absent and only four rays were visible in the right foot.
Traction was applied as described for Case No. 1. At examination on August 12, 1968 (six months after the beginning of traction), shortening of the right leg was measured as being 5 cm, i.e., the same as at the beginning of the treatment. X-rays showed improved alignment of the femoral diaphysis. The femoral head was not visible.
The application of permanent traction has been possible only because of active collaboration by intelligent mothers and skilled orthotists. Our few cases have been followed for only a short time; hence, it is not possible to draw long-range conclusions. However, the outcomes may be taken as promising and, in all cases to date, flexion contractures have been prevented.
If the second and third cases develop in a manner similar to Case No. 1, it is possible that this approach will help us achieve stable hips-and an improved basis for further procedures. If the leg-length differences remain below the 10 cm level, a later intervention may provide further correction. This correction would preferably involve bone lengthening and epiphysiodesis. Further experience in the described procedures is needed and it is my hope that colleagues in charge of treatment programs for these types of deformities will consider undertaking this procedure and thus help to contribute the additional experience needed.
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Knud Jansen, M.D. is associated with the Orthopaedic Hospital of Copenhagen, Denmark