Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

­deficiency (complete absence), the authors recommend knee disarticulation and prosthetic fitting. The authors have not seen any patients as described in the literature with com- plete tibial absence yet the presence of adequate active knee extension, but would recommend knee disarticulation and prosthetic fitting for these patients as well because of its high functional result compared to the poor functional results reported for the Brown procedure. For patients with some active knee extension and Jones type 1b or type 2 tibial defi- ciency, the authors recommend waiting for the tibial rem- nant to ossify, then performing a tibial–fibular synostosis in an end-to-end fashion. At the same time as the synostosis, a modified Boyd amputation is performed, with fusion of the distal fibula to the calcaneus. If the proximal fibula is proximally displaced, prominent, and if the knee has varus deformity or instability, resection of the proximal fibula is recommended as well. Timing of the tibial–fibular synostosis, modified Boyd amputation, and possible proximal fibular resection is under- taken at approximately 1 year of age unless the proximal tibia is unossified. The authors recommend fitting the child with an unossified proximal tibia with an extension prosthosis that accommodates the foot deformity and waiting until the proximal tibia ossifies. This has the benefit of one definitive surgical episode while allowing the child to walk at a nor- mal developmental age and has the added benefit of saving the toes for possible transfer to the hand if hand anomalies coexist. The authors have no experience with Jones type 3 tibial deficiency but agree with Schoenecker that ankle disarticula- tion and prosthetic fitting are appropriate. For Jones type 4 cases and a projected limb-length discrepancy of 5 cm or less, the authors recommend early soft-tissue correction of the foot deformity with later contralateral epiphysiodesis to achieve limb-length equality. For those cases with a projected discrep- ancy above 5 cm, Syme amputation and prosthetic fitting is preferred. Pearls/Pitfalls.  As mentioned previously, outcomes of fibular centralization are poor. The literature suggests that this almost uniformly results in a poor functional result and subsequent knee disarticulation. Initial knee disarticulation in patients without active knee extension results in less surgery and a more functional result. During tibiofibular synostosis surgery, a few points are worth mentioning. The proximal fibula in these patients often is proximally displaced and prominent laterally. The surgeon should consider resection of this at the time of tibiofibular syn- ostosis surgery so it does not cause difficulty with prosthetic wear in the future. With regard to the technique of synostosis, the authors have found that end-to-end apposition of the tibia and fibula results in superior lower limb alignment for pros- thetic fitting. The fibula usually needs to be slightly shortened to take tension off of the soft-tissue structures to achieve this alignment, which is of no consequence.

­prosthetic approaches to management. In children with type I tibial deficiency who have been treated with knee disarticu- lation and have a flare at the condyles, the prosthetic socket consists of a nonischial weight-bearing design with rotational control achieved through the intimate fit of the distal end of the socket over the femoral condyles and a well-formed glu- teal impression. Suspension is usually achieved with the use of a segmented liner or bladder design that allows the wider condyles to pass through, while maintaining pressure over the femur just proximal to the condyles. In cases in which the condyles are absent or there is the need to fit with a transfemoral socket, rotational control is achieved through proper contouring of the socket relative to the femur—the musculature surrounding the femur has a slight triangular shape in a cross-sectional view, with a flatter contour on the lateral surface, especially proximally. This allows a lock- ing of the musculature which, with proper socket fit, decreases rotation. In addition, a silicone sleeve suspension may be used in conjunction with a pull-through strap to secure the liner. If all other procedures fail, a standard Silesian belt (around the pelvis) may be utilized. The total elastic suspension (TES) belt offers excellent suspension and flexibility of form, and it aids in control of the prosthesis. However, the Silesian belt and TES will interfere with grooming and toilet training. In the knee disarticulation (or transfemoral) prosthesis for children, there are differences of opinion as to when young children are able to handle an articulated knee. Traditional established practice is to first fit the child with a locked knee and allow an articulating knee at approximately 3 to 5 years of age. In contrast, Wilk et al. (157) advocate the use of artic- ulating knees in children as young as 17 months. Children as young as 11 months can be appropriate candidates for articulated knees (155). The children learn how to handle the knee very quickly, and there is very little need for any type of device to temporarily stabilize the knee. The use of a knee joint at this stage permits more normal ­development, ­allowing bent-knee sitting, side sitting, crawling and kneeling on hands and knees, and easier pull to a stand. With a pedi- atric knee, children can reduce or eliminate a circumducted gait pattern. In type II cases, in which a tibial segment has been pre- served or the fibula has been joined to the tibial remnant, a modified transtibial prosthesis or a Syme prosthesis is uti- lized. Unlike the standard transtibial design, the socket will incorporate SC and suprapatellar proximal brim lines that will aid in the control and stability of the knee and prevention of a hyperextension moment, respectively. In some instances in which knee stability is less than optimal, outside joints and a thigh cuff or lacer may be required. These are used as a last resort and often contribute to increased weakening of the musculature as a trade-off for increased control and alignment. Authors Preferred Recommendations.  For patients with no active knee extension and Jones type Ia tibial