Congenital pseudarthrosis and bowing of the fibula.

The purpose of this paper is to describe experience with four children who presented with bowing or pseudarthrosis of the fibula. These children demonstrate a gradation in the severity and significance of this condition. There may be : 1) fibular bowing without fibular pseudarthrosis (Case 1); 2) fibular pseudarthrosis without ankle deformity (Case 2); 3) fibular pseudarthrosis with ankle deformity but without the late development of tibia! pseudarthrosis (Case 3) ; or 4) fibular pseudarthrosis with the late development of pseudarthrosis of the tibia (Case 4). The aetiology and pathology of bowing and pseudarthrosis of the fibula are similar to those of antero-lateral bowing and pseudarthrosis of the tibia. Similar conditions affect other bones developed by endochondral ossification-the first rib, clavicle, femur, radius and ulna. Thus pseudarthrosis in the fibula may occur after fracture through a congenital cyst or an area of fibrous dysplasia, or occasionally in neurofibromatosis. Fracture may also occur through an area of mesoderma! maldeve!opment in which the diaphysis is tapered, sclerotic and often bowed and the cortex thickened, with a narrowed or obliterated medullary cavity. Pseudarthrosis or bowing may involve the fibula alone, but more commonly it is associated with abnormalities in one or both tibiae. Langenski#{246}ld (1967) described three cases of progressive valgus deformity of the ankle with persisting pseudarthrosis of the fibula following successful bone grafting for a pseudarthrosis of the tibia. Carrel! (1938), Boyd (1941) and Boyd and Sage (1958) also mentioned similar cases. Boyd and Sage described a case of congenital pseudarthrosis of the fibula with a normal tibia. The opposite leg was affected by pseudarthrosis of both bones.