Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

Complications.  The complications of Syme versus Boyd amputation were previously discussed in the section on fibular deficiency. In patients planned to have a tibiofibular synostosis, non- union can occur, particularly if the tibial segment is unossi- fied. The authors suggest waiting for tibial ossification before attempting synostosis, even if it delays the achievement of nor- mal motor milestones for the child. Just as progressive foot deformity can occur with tibial length- ening in fibular deficiency, worsening of foot deformity can occur after previous correction of the foot in type 4 tibial deficiency. Stabilizing the ankle mortise with a distal tibial/fibular synostosis and including the foot in the Ilizarov frame during lengthening conceptually should reduce this complication. Another solution is to fuse the distal fibula to the posterior facet of the calcaneus, thereby stabilizing the foot under the fibula (147). Femoral Deficiency Definition and Classification.  The term “femoral defi- ciency” encompasses a wide-spectrum pathology, varying from a short but relatively normal femur to almost total absence of the femur with only the distal femoral condyles present. Aitken popularized the term “proximal femoral focal deficiency” to refer to the more severe forms of this disease, although the deficiency is not isolated to the proximal femur and is often part of a global limb deficiency. There have been numerous classifications of PFFD (32, 34, 73, 158–162). Some systems are radiographic in nature, while others are treatment based. For those that are treatment based, classification groups are slightly different, which reflect the dif- fering opinions on optimal treatment. No classification system adequately describes the whole spectrum of the limb deficiency, which includes both bone and soft-tissue anomalies. The Aitken classification is the most widely used system (158). It is a radiographic classification system based on the severity of the radiographic findings of the hip and femur. As is true with all radiographic classification systems where there is temporal evolution of the radiographic findings, the ­classification of a particular patient may change over time as the radiographs evolve. Goddard et al. suggested that the Aitken classification was easier to apply to a radiograph taken at 12 to 15 months of age, when the child is starting to stand and walk, rather than one taken immediately after birth (163). In class A, the femur is short, with the most proximal ossi- fied portion at or slightly above the acetabulum [Fig. 30-25: (Right)]. There is incomplete ossification in the subtrochan- teric region of the femur which will ossify over time. There is often a subtrochanteric varus deformity with ossification. The femoral head may not be visible on radiographs, but there is a well-formed acetabulum that implies its presence. In class B, there is a more extensive defect or absence of the proximal femur (Fig. 30-26). The acetabulum shows more signs of dysplasia than in type A. In addition, the most proxi- mal part of the femur is part of the femoral shaft, which is located above the level of the acetabulum. The radiographic

defect in the subtrochanteric region, in contrast to class A, does not ossify with time and instead forms a pseudarthrosis. In Aitken class C, the acetabulum is severely dysplastic [Fig. 30-25 (left)] and (Fig. 30-27), signifying that the femoral head is absent and will not ossify with time. The femoral shaft is shorter than in class B, and the entire proximal femur does not ossify with time. In Aitken class D, the femoral shaft is essentially absent (Fig. 30-28). The distal femoral condyles are seen at the level of where the acetabulum should be. The lateral pelvic wall is flat, without any evidence of acetabular development. Gillespie (134) proposed a three-tiered classification system based on treatment recommendations rather than radiographs. Group A are those with congenital short femur indicated by clin- ical hip stability, lack of significant knee-flexion contracture, and the foot of the affected extremity lying at or below the midpoint of the opposite tibia (Fig. 30-29). These patients have a hip that is stable to weight bearing and a femoral segment that is >60% of the contralateral side. These patients are likely candidates for limb lengthening. His group B patients include patients with a hip that is unstable with weightbearing and have a ­femoral FIGURE 30-25.  AP pelvis of an 18-month-old child with bilat- eral PFFD. The right hip is an Aitken class A and demonstrates the presence of the ossific nucleus and a good acetabulum. The femo- ral metaphysis lies above the level of the ossific nucleus. There is a cartilaginous connection between the metaphysis and the femoral head, which will usually ossify by skeletal maturity, but often with a significant varus deformity. The opposite hip is an Aitken class C PFFD. This patient demonstrates the difficulty with limb-length difference in some patients with bilateral PFFD.