Weinstein Lovell and Winters Pediatric Orthopaedics 7e

1587

CHAPTER 30  |  The Child with a Limb Deficiency

Partial-foot Prosthesis.  The most important consider- ation in the fitting of the partial-foot amputee is to ensure that adequate load-bearing is designed into the prosthesis of choice. As a general rule, the more proximal the level of amputation, the higher the prosthesis must fit over the ankle complex and the more proximally it must fit on the tibia and fibula. Tissue condition, function of the remaining foot complex, and activ- ity of the child all play a role in determining the prescription and design of the prosthesis. Complete or partial absence of the toes usually requires little more than a shoe filler. A carbon fiber insert to better control forces from heel to toe-off may be incorporated in the shoe filler. In the case of the very young child, no interven- tion may be required until a need has been demonstrated, for example, the inability to keep the shoe on, especially when the child becomes more active in sports. The prosthesis most commonly used for the moderate/ short partial-foot amputee is the Lange silicone partial-foot prosthesis (Fig. 30-53). This incorporates a cosmetic foot shell, silicone-laminated socket with modified foot sole, and a pos- terior zipper for ease of donning and doffing. The prosthesis is fabricated over a modified model of the patient’s partial foot. The socket trim line is proximal to the malleoli and is fitted intimately to ensure adequate control. The design of a partial- foot prosthesis may also include a removable insert, to accom- modate the need for corrective alignment of the residual foot. The prosthesis is then cosmetically finished to resemble the contralateral limb. Overall, this type of prosthesis is perfectly suited for the child amputee and resists premature wear and tear. If needed, a partial-foot prosthesis should be prescribed once the child is pulling to furniture, so that foot control will begin at an early age. It should be noted that a low-profile insert (distal to the malleoli), used in conjunction with a high- top boot, will offer adequate function and cosmesis until a lower cut shoe is requested by the parent. The Chopart, or midtarsal, amputation is rarely used except in special instances (230). In the Chopart partial-foot amputa- tion level, the prosthesis is modified to encompass the calcaneus

and talus, and this results in a prosthesis that is often longer than the contralateral limb. The prosthesis must encompass the ankle joint, and it often rises proximally to the patellar tendon in an effort to reduce forces on the tibial crest–socket interface. Selection of prosthetic feet is compromised because of the lack of space distally, and commercially available carbon foot plates require permanent attachment with vulcanizing rubber cement. This negates any changes caused by growth, and realignment to compensate for gait changes is virtually impossible. Terminal Devices for the Upper Extremity.  The choices left open to the prosthetist are numerous and, at times, controversial. Where some clinics maintain rigid protocols for terminal device selection, other clinics rely more on patient and parent input, combined with historic success rates for device types. Clinics that maintain very high caseloads for myoelectric devices, for example, will most likely have far more experience in fitting externally powered prostheses, compared to a clinic that may only see a handful of potential myoelectric candidates. In simple terms, the terminal devices can be divided into hands and hooks, and they can be body powered (cable and harness) or externally powered (electric). Hands and hooks can be either voluntary opening or voluntary closing. Patton lists the functional and prescription criteria for the various terminal devices (203). The initial fitting of a child with upper extremity limb deficiency begins at 4 months of age in a passive prosthesis with a stylized passive hand. There are several hands manufactured for this age range (Fig. 30-54A). This allows for equal arm lengths for the development of propping up on the amputated side and greater acceptance by the parents. Following initial sit- ting balance, the clenched-fist terminal device is exchanged for a small infant passive hand. When the infant begins to reach out (at ∼ 15 to 18 months of age), the clinic team begins to assess the need for either body-powered or externally pow- ered prostheses. If body-powered prosthesis is ­recommended, a cable-operated Hosmer 12P plastic-covered hook (Fig. 30-54B) or an ADEPT infant hand (Fig. 30-54C) will be

B FIGURE 30-53. A : The Lange silicone partial-foot prosthesis is a custom-made prosthesis that can incorporate a keel to aid in foot stability and push-off in gait. B : It is useful for children with partial amputations of the foot or congenital longitudinal defi- ciencies of the foot, shown here. It is not useful in feet with insufficient length, for example, those with the Chopart amputation.

A