Proximal Femoral Focal Deficiency- Quo Vadis?

RICHARD E KING, M D. THOMAS McCRANEY, M.D.


Congenital pseudarthrosis is a specific type of nonunion that is either present or incipient at birth. The cause is not known, but the condition appears to be related to neurofibromatosis. Congenital pseudarthrosis usually involves the distal half of the tibia and fibula of the same limb. It has also been seen in the clavicle, first rib, humerus, ulna and femur.

Recently we have come across three patients with short femurs that have proven difficult to fit into the Aitken's PFFD classification system. The status of each of these cases was originally misinterpreted, but with additional study and growth they were finally classified correctly. All had the conventional stigmata of a shortened extremity, a markedly thickened thigh segment with flexion, abduction and external-rotation contractures, an absent fibula, a dimple over the distal third of an anterior-bowed tibia and an equinovalgus foot.

Case Reports

Case 1.-R.S., the product of an uncomplicated labor, was noted at birth to have a short femur, an absent right fibula and marked eversion of the right foot (Figure 1) Casts were applied for correction of the foot and at 15 months of age the child was fitted with an ischial weight-bearing brace. X-ray evaluation at three years of age suggested a "pseudarthrosis" of the femur. Subsequent x-rays at five years of age showed the same bending of the femur at the pseudarthrosis site but suggested that healing was occurring (Figures 2 through 6). At age 7, the defect appeared to be almost "closed," but one year later the patient fell and fractured the femur through the "pseudarthrosis" site (Figures 7 through 10). Subsequent healing completely obliterated the fracture site.

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Case 2.-D. M. was seen at Grady Memorial Hospital at the age of four months with a diagnosis of PFFD. At eight months it was felt that this deficiency represented either a healing fracture or a congenital pseudarthrosis. Subsequent follow-up showed healing of the defect (Figures 11 through 16).

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Case 3.-M. W. was seen at the age of eight months and was considered to exhibit Type A PFFD (Figure 17). The patient was subsequently fitted with an ischial weight-bearing brace. It was felt that if bending occurred at the level of the defect, an osteotomy would be needed to prevent increasing varus deformity However, as shown in Figure 18, subsequent x-rays of the limb (out of the brace) showed a Type B PFFD (apparently the weight of the brace exerted traction on the extremity and tended to give a reasonable femoral neck shaft angle)

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Discussion

Each case has been described from the initial to the final impressions. Cases 1 and 2 could not be fitted into Aitken's classification scheme and were felt to represent congenital pseudarthrosis of the femur. Some cases of this type we have seen have undergone osteotomy of the femur to prevent further bending of the femur at the pseudarthrosis site. In other cases treated without osteotomy the "pseudarthrosis" line closed with maturation and eventually underwent ossification, much as the pseudarthrosis in PFFD Type B undergoes ossification when a single skeletal lever is created and the lever is placed in the functional weight-bearing position. The femurs of these patients probably represent a precursor to Type A, in which a full-blown "pseudarthrosis line" goes on to ossification. This then could not represent congenital pseudarthrosis which would not ossify when placed in a functional weight-bearing line of stress.

Badger and Lambert1 have presented postmortem findings on a newborn who expired within 12 hours after birth. This child had defects similar to Cases 1 and 2. Because of a bluish coloration in the proximal quadriceps muscle and microscopic findings, they felt that the condition represented an old (intrauterine) fracture of the proximal femur.

It is difficult for the authors to agree that these cases represent old fractures of the femur. Rather it is felt that since they have all the stigmata of PFFD, i.e., flexed, abducted, externally rotated hips, short femurs and absent fibulae, they represent precursors to Type A proximal femoral focal deficiencies.

It is now our feeling that osteotomy should not be attempted in Type A unless one is able to see definite evidence of progressive bending at the site of the "pseudarthrosis." Unless this corollary condition is present, some of these defects will proceed to union and obviate the need for surgery.

Case 3 was felt to represent Type A with a typical "pseudarthrosis" line present, and it was not until push-pull x-rays were made that its true nature became revealed as Type B.

Conclusions

Congenital pseudarthrosis defects in long bones do not heal spontaneously, but occasionally defects in the femur do and thus cannot be classed as pseudarthrosis. Linear defects in the upper femur should not be classified as congenital pseudarthrosis until their developmental life has been examined. In certain manifestations of Type A PFFD, we should not rush into osteotomy to include healing of the pseudarthrosis as it may ossify of its own accord.

If the pseudarthrosis line in the femur is complete, push-pull x-rays may reveal its true nature as Type B PFFD, which would necessitate reconstruction of the skeletal lever.

It is becoming obvious that Aitken's PFFD classification indicates a teratological sequence of PFFD from mild to more severe deformities2. Perhaps Case 1 described above belongs in this classification sequence ahead of Type A, i.e., as the very early beginnings of PFFD formation.

State of Georgia Juvenile Amputee Clinic Atlanta, Georgia

References:
1. Badger, V., and C. Lambert, Differential diagnosis of an apparent proximal femoral focal deficiency. Inter-Clin. Information Bull., 5:1:3-9, October 1965.
2. Henkel, L., and H. G. Willert, Dysmelia: A classification and a pattern of malformation in a group of congenital defects of the limbs. J. Bone and Joint Surg., 51-B:399-414, August 1969.