Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

untreated. Children with more severe forms often choose to walk on the knee of the unaffected side to make up for the severe limb-length discrepancy during the first few years of life until the discrepancy is severe and treatment is sought. Treatment Recommendations Nonsurgical Treatment.  Most patients will benefit from a treatment plan that includes surgical intervention, be it length- ening, amputation, or rotationplasty. However, there are few reports that demonstrate patient-perceived outcomes of ampu- tation and prosthetic fitting versus accommodative prosthetic fitting without amputation have similar function results (170). Thus, accommodative prosthetic fitting might be an option for the rare patient who does not want to undergo any surgi- cal intervention. More often, however, prosthetic fitting is a bridge treatment instituted when the child is ready to walk until age 2 1/2 to 3 years of age, when definitive treatment is planned. This prosthesis is nonconventional in design and is sometimes referred to as an extension prosthesis or a “prost- hosis.” It is designed to fit the extremity without any surgi- cal modification to it (Fig, 30-33). The flexion, abduction, and external rotation of the proximal segment (the femur) are accommodated in the alignment. At this young age, the knee joint of the prosthesis can be omitted. The treatment of children with bilateral PFFD is predom- inantly nonoperative. These children do not use prostheses. Occasionally, if there is asymmetric involvement of the limbs, a limb-length discrepancy can exist. Treatment is individual- ized to each patient. Surgical Treatment.  Surgical treatment aims to compen- sate for the functional problems the patient experiences. The most obvious of these is the shortening of the limb. Less obvious is the problem with hip function and its rela- tion to the alignment of the limb. Because of the flexed and

­externally rotated femoral segment, the knee remains flexed, and the leg and foot are anterior and lateral to the axis of the body (Figs. 30-32 and 30-33). Without surgical treat- ment, the patient must lean laterally and posteriorly during stance phase on the affected limb to move the weight-bear- ing line so that the proximal femoral segment will be more stable. This gait pattern is accentuated because of the addi- tional muscle deficiency around the hip. The knee will have varying degrees of instability. The function of the foot will depend on the severity of any associated deficiencies of the leg, for example, fibular deficiency. There are three main treatment strategies for PFFD patients; knee fusion with foot ablation, Van Nes rotation- plasty with knee fusion, and limb lengthening. Each strategy is vastly different from the other, and early decision making is necessary to put the child on the proper path. Fortunately, most of these decisions can be postponed until 2 1/2 to 3 years of age, because this is the best age to perform these surgical options. Most authors suggest limb lengthening if the predicted discrepancy at maturity is <20 cm; the hip is, or can be, made stable; and there is good knee, ankle, and foot stability and motion. Such cases require multiple-staged lengthenings in addition to a contralateral epiphysiodesis and sometimes a shoe lift. The timing and staging of these procedures depends on the choice of the physician, but will usually not start before the age of 3 years. Reports of the functional outcome in patients followed up to maturity and into adulthood are lacking. If the discrepancy is predicted to be >20 cm at maturity, or for any other reason lengthening is not chosen as a treatment, a decision should be reached about the best approach to prosthetic fitting. Surgery can make the residual limb a more efficient lever arm to power the prosthesis. In addition, foot ablation can lead to a more cosmetic appearance of the prosthesis. Knee Arthrodesis.  Arthrodesis of the knee joint is a standard procedure in children with PFFD undergoing prosthetic fit- ting. It creates a single, longer, and more efficient lever arm, which is easier to contain within the prosthesis. This will greatly enhance prosthetic function and reduce energy con- sumption. The proximal femoral segment deformity (flexion, abduction, and external rotation) does not need to be compen- sated for at the time of knee fusion. If the tibia is fused in line with the femur, subsequent ambulation with a prosthesis will gradually correct the soft-tissue balance around the hip and realign the limb with the contralateral side. Depending on the length of the femoral segment and the limb as a whole, it is usually desirable to remove at least one of the growth plates at the knee at the time of fusion. This is usu- ally the case in Aitken class A, B, and C deformities. Without removing at least one of the epiphyses and physes at the knee, the limb will be too long (Fig. 30-34). The reason for this is that most above-knee prosthesis designs need approximately 7 cm to accommodate a prosthetic knee joint. If the ipsilateral lower leg segment is normal in length or mildly shortened, as it often is, then the growth of the lower leg segment alone will

FIGURE 30-33.  Lateral photograph of a patient with an extension prosthesis that accommodates the retained foot proximal to the terminal end of the prosthesis. This type of prosthesis can be useful if the parents refuse foot removal or in the young toddler before definitive treatment.