Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

FIGURE 30-20. A,B : AP and lateral clinical photos of a patient with fibular absence who had a Syme amputation with heel pad migration. The heel pad has migrated posteriorly, and the patient has a painful discolored area over the distal tibia from weight bearing.

Tibial Deficiency Definition and Classification.  The most common clas- sification system of tibial deficiencies is the Jones classification, which is a modification of the earlier Kalamchi and Dawe clas- sification (99). The Jones classification is based on the radio- graphic appearance of the limb within the first year of life. In type 1 tibial deficiencies, ossification of the tibia is absent. In type Ia, there is hypoplasia of the femoral epiphysis, implying a complete lack of any tibial anlage articulating with the distal femur (Fig. 30-21). In these children, the extensor mechanism is usually severely deficient or absent. In rare cases, bifurca- tion of the distal femur can be an associated finding in these patients. In type 1b tibial deficiencies, the femoral condyles are more developed, implying there is a cartilaginous tibial anlage present that articulates with the distal femur (Fig. 30-22). This anlage eventually ossifies with further growth usually between 2 and 4 years of age. These patients often have a functioning extensor mechanism. Jones type 2 tibial deficiency has a proximal tibia with absent ossification of the distal tibia. This group is the same

Lengthening.  One complication specific to these patients is subluxation of the knee or ankle during lengthening. At the knee, posterior subluxation of the tibia and development of a progressive knee-flexion contracture can be seen with femoral lengthening. This happens because there is a high incidence of cruciate ligament dysplasia in these patients. Prevention of this problem before it occurs is best, which can be accomplished by using a hinged knee orthosis that can be locked in exten- sion, performing an extra-articular anterior cruciate ligament reconstruction, and/or by spanning the knee joint with the external fixator with a hinge placed at the knee joint during lengthening. Progressive subluxation can also occur at the ankle joint with lengthening of the tibia. These patients often have abnor- mal lateral supporting structures, including the lateral malleo- lus and lateral stabilizing ankle ligaments. Inclusion of the foot in the fixator frame is one treatment which has some ­success in preventing the complication (122). If the complication ­develops, subsequent ankle soft-tissue stabilization, distal tibia osteotomy, or fusion may be necessary (123).