Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

­recommended against the Brown procedure in cases of com- plete absence of the tibia. In patients with Jones type 1b tibial deficiency, it is important to monitor the patient over time, both for ossifica- tion of the proximal tibial remnant and to verify good active extension. It is possible that this remnant will be present, but good active extension will be absent or the remnant will not ossify. If there is active extension in a child, but the remnant is not sufficiently ossified by 1 year of age, the surgeon has several choices. The patient may be fitted with an extension- type prosthesis that accommodates the current foot position. Although this prosthesis (or prosthosis) is cosmetically unap- pealing, the child is usually quite functional. Alternatively, the surgeon may attempt to transfer the fibula to the unossified tibial segment with the goal of obtaining a successful tibial/ fibular synostosis. Lastly, the physician can perform a Syme or modified Boyd amputation, fit with a prosthesis, and wait for ossification before performing the transfer. In the rare patient with type Ia tibial deformity and proxi- mal femoral deficiency with a very short limb, the best option may be to arthrodese the fibula to the distal end of the femur. The goal of this procedure is to increase the lever arm of the femoral segment, for the same reasons that a knee fusion is performed in children with PFFD. In Jones type 2 deficiencies, the treatment of choice is to create a synostosis between the existing fibula and the tibial remnant to increase the length of the lever arm. A Syme or modified Boyd amputation, where the calcaneus is fused to the distal fibula instead of the tibia, is performed at the same time, and the patient is fit with a BK prosthesis (Fig. 30-24). Whether the synostosis is performed side-to-side or ­end-­to-end, it is important to achieve good alignment of the fibula in relation to the knee joint. The residual ­proximal

fibula should be removed to avoid problems later with pros- thetic fit. Type 3 deficiencies of Jones are very unusual, and there is not much published experience. Jones et al. reported one case that was bilateral (148). They described a cartilaginous por- tion of the tibia, proximal to the ossified portion, which was “under voluntary muscle control.” Their patient was treated with excision of the proximal fibula and Syme amputation. Fernandez-Palazzi et al. (127) had two cases in their report. Both were treated with Syme amputation, implying that there was an active quadriceps mechanism. Jones type 4 deficiency presents a unique problem. At birth, the foot is deformed, often appearing like a clubfoot to the inexperienced. In addition, the amount of tibial shortening that will result is not apparent. This all makes it difficult for the parents to accept amputation. The difficulty for the surgeon is that this deformity is a spectrum of deformity. Garbarino et al. (149) have emphasized the distinction between a short tibia with a varus foot and a true congenital diastasis of the ankle joint. The former is usually amenable to reconstruction according to Schoenecker (131), whereas the true type 4 defi- ciency with diastasis of the ankle joint usually is treated with amputation (148, 150). There are reports of reconstruction for the type 4 deficien- cies, but in general the follow-up is short and the problems of a plantigrade foot and limb-length discrepancy are just begin- ning in these patients (149, 151–153). One patient followed up to the age of 15 years is described as having satisfactory ankle function and 6.5 cm of shortening (154), while another followed up to the age of 10 years (6 years after reconstructive surgery) is reported as having a stable ankle and plantigrade foot, but projected limb-length discrepancy is not mentioned (155). Choi et al. have recently reported on three patients treated with foot deformity correction with an Ilizarov device followed by distal tibial/fibular synostosis to stabilize the ankle mortise. This was followed with limb lengthening, includ- ing differential lengthening of the tibia and fibula. At skeletal maturity, all three had a plantigrade foot, less than a 3-cm leg- length discrepancy and were able to participate in group games or sports (156). In their review of tibial deficiencies, Schoenecker et al. (130) reported on 10 patients with Jones type 4 deficiencies, of which nine had initial reconstruction of the foot. A Syme amputation was subsequently done in six of them, usually at the parents’ request. Of the four patients who retained the foot, two had contralateral deficiencies in which the prosthesis accommodated the length discrepancy. One had a lengthening of 4.6 cm and one remained 4.8 cm short. From the available information, it seems reasonable to attempt to retain the foot, if the deformity is at the less severe end of the spectrum, or if there is a significant contralateral deficiency. In most other cases, Syme amputation seems most reasonable.

FIGURE 30-24. A,B : Pre- and postoperative lateral radiographs of a patient with type 2 tibial deficiency. The patient has undergone an end-to-end synostosis of the tibia and fibula with proximal fibular resection and a modified Boyd amputation with fusion of the calca- neus to the distal fibula.

Prosthetic Management.  Depending on the severity of the anomaly and the surgery performed, there are several