Congenital Reduplication of the Femur Associated with Paraxial Fibular Hemimelia: A Preliminary Report

Dennis S. Weiner, M.D. Barry Greenberg, M.D. Norm Shamp, C.P.O.


In early 1972, a four-month-old male seen in consultation exhibited a congenital limb deficit of a type heretofore undescribed, to our knowledge1. Srivastava and Garg, in 19712, described a child with reduplication of the bones of an entire lower limb, and referred to a few additional cases reported in the literature. The child seen by us presented a rather different picture which, for the most part, coupled the reduplication of a long bone with a congenital deficiency. The combination of these anomalies posed a distinct problem regarding the most appropriate type of surgical conversion to enhance the probability of a suitable prosthetic fitting.

Case Report

This four-month-old male was seen initially at Akron Children's Hospital with a shortened and malrotated left lower limb (Fig. 1 ). The girth of the left mid-thigh measured nearly one and a half times that of the right. A rigid knee-flexion deformity of 90 deg. was present. The lower-leg segment was considerably shortened and was without a palpable fibula. A rather rigid metatarsus adductovarus was present but the hindfoot was free of deformity. Radiographic examination confirmed the presence of a reduplicated femur, accompanied by an intercalary longitudinal complete paraxial fibular hemimelia (Fig. 2 ). One femur formed an articulation at the acetabulum. It also articulated with the proximal tibia to form a knee joint Proximally, the other femur seemed simply to lie adjacent to the articulating femur. Distally it appeared to be connected to the posterior aspect of the knee by a soft-tissue bridge of unknown type.

After due consideration, an attempt was made to unravel the knee-flexion deformity surgically when the child was five and a half months old. The distal end of the reduplicated femur was found to be tensely affixed to the posterior knee-joint capsule. Also, tough fibrous bands of connective tissue passed from this region to the proximal tibia and progressively downward to the distal tibiotalar joint in the area normally occupied by the fibula. Encased in the fibrous bands that had held the knee fixed in flexion, lay the popliteal artery, nerve, and branches, which were freed by meticulous dissection. After resecting one and a half inches of proximal tibia, the knee-flexion deformity could be reduced to 20 deg., at which point discretion suggested that the surgeon refrain from attempting to gain additional correction because of tension on the neurovascular bundle (Fig. 3 ).

At age seven months the boy was fitted with a quadrilateral-shaped, ischial weight-bearing socket. The foot was in equinus and nonweight-bearing but in contact with the bottom of the socket by means of felt pads. The socket and shin were all in one piece, i.e., without a mechanical knee and sized to make up for the leg-length discrepancy. A SACH foot and pelvic suspension completed the assembly.

When the child was one year of age, additional malrotation of the foot on the ankle became evident. It was also felt that the soft tissue connections from the hindfoot to the posterior aspect of the knee would tend to bring the knee into further flexion. Accordingly, the foot was disarticulated at the ankle. At the age of eighteen months, stump length from greater trochanter to distal end measured eight in. and the youngster was fully ambulatory, with a knee-flexion angulation of 15 deg. apparent radiographically. He was fitted with a prosthesis similar to the one described but with weight-bearing on the ischial tuberosity and at the ankle-disarticulation stump.

Discussion

Aside from the unusual nature of our patient's deformity (i.e., reduplication and partial limb absence), this case highlights some very important considerations in the treatment of the limb-deficient child. If one could overlook the bizarre nature of his radiographs, we could then appreciate that his deficits were similar to nearly all major lower-limb absences. That is, they involved leg-length inequality of a significant nature, malrotation of a part or all of the limb, proximal joint and proximal soft tissue abnormalities. In treatment an attempt was made to resolve all these problems.

Initially, it was felt that a better knee position would be useful by providing a potentially long lever for prosthetic operation. The initial surgical release coupled with an intra-articular resection of a portion of the proximal tibia served this purpose well and, fortuitously, resulted in an early arthrofibrosis of the knee in roughly 15 to 20 deg. of flexion. Later, the ankle disarticulation helped remove a deforming force and paved the way for eventual fitting with an articulated, above-knee-type prosthesis. Knee arthrodesis, and perhaps even stump shortening, might possibly be necessary in the future.

Summary

An unusual case of reduplication of the femur associated with terminal longitudinal complete paraxial fibular hemimelia is presented. The surgical findings are described and the rationale for surgical conversion to achieve an optimal prosthetic fitting condition is proposed. It is contemplated that an above-knee type of prosthesis will be the eventual permanent appliance.

Akron Children's Hospital Akron, Ohio

References:
1. Aitken, G., Personal communication.
2. Srivastava, K. K., and L. D. Garg, Reduplication of bones of lower extremity. J. Bone and Joint Surg., 53-A:7:1445-1447, October 1971.