Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

unsuitable for a different child with the same anomaly. Rigid time schedules are discouraged, and developmental levels should be used only as a rough guideline to aid the practitioner. Fitting the child with limb deficiency leads to unique issues not normally seen in the adult population. Knee disarticulations can lead to long residual limbs with knee centers lower than on the sound side. Ischial containment sockets are not normally recommended (unless needed because of hip instability or non- distal weight bearing) because of problems with soft-tissue con- tainment and diapers in infants. Location of bony landmarks is obscured by fatty tissue, and casting is difficult and nonexact. The various stages involved prior to fitting a prosthesis are generally standard within the profession. Upon referral to a clinic, the child is assessed by the team, and a treatment protocol is established. The stages involved in prosthetic fitting include: 1.  CASTING of the residual limb. 2.  TEST FITTING of the modified interfacing socket. 3.  DYNAMIC ALIGNMENT AND GAIT TRAINING . 4.  DELIVERY of the completed prosthesis. Socket Design and Suspension Systems.  The cast or impression forms the foundation for the prosthetic design (216). It is only after a well-fitting and comfortable socket– skin interface is achieved that the additional components can be added and expected to function as designed. Casting usually involves the placing of a casting sock on the residual limb, marking all landmarks and wrapping circumferentially with plaster or synthetic bandage. This becomes the negative impression. It is then filled with molding plaster and stripped, forming the positive cast ready for modification. This positive cast is then modified to distribute forces and relieve pressure in the socket for proper hydrostatic control of the residual limb. Through the use of a clear test or diagnostic socket fabri- cated over the positive mold, the practitioner is able to ascertain the areas of high and low pressure and to ensure that they are directed over the appropriate areas. Common fitting problems can be flagged and corrected before the final socket design. Computer-aided design/computer-aided manufacture (CAD/CAM) has been used as an alternative tool to plaster casting and modification of the prosthetic socket. In its most simplified form, a residual limb is scanned with an optical laser. The information is relayed to a computer, with which modifica- tions can be made to the scanned shape to allow for increased or decreased weight-bearing areas. The finished design is trans- ferred to a computerized milling machine to form a positive model. This, in turn, is used to fabricate the finished device. Slowly, CAD/CAM is becoming more widely used within the profession, because of advantages of design reproducibility, record keeping, and flexibility in remote locations (217). Its advantages in the pediatric setting have yet to be proven. All current CAD/CAM systems rely on surface topography of the residual limb and therefore disregard crucial data such as tissue density, tissue mobility, and underlying skeletal structures (218). During dynamic alignment in the crawling infant, the prosthetist initially focuses on creating a prosthesis that will

There remains a difference of opinion about the benefit in fitting the acquired juvenile amputee in the immediate postop- erative period. In the young child with a congenital deficiency, there seems little to be gained. However, in the older child, especially when the amputation is caused by trauma, there can be large psychological benefits from placing the child imme- diately in a postoperative prosthesis. This also aids in edema control diminution of phantom pain. Prosthetics In the prosthetic fitting of the pediatric amputee, the single- most important guiding principle is that functional concerns always override cosmetic ones. When dealing with the adult population, overall biomechanical forces resulting from pros- thetic alignment can do relatively little damage to skeletal integrity. This is not the case for the pediatric patient, in whom skeletal development is ongoing. Incorrect alignment can have long-term and often pronounced negative results. Role of the Prosthetist.  The role of the prosthetist is to ensure that the highest level of functional need of the patient is met through prosthetic intervention, or through no inter- vention at all if indicated. The skilled prosthetist can assess anatomic and functional deficiencies and recommend socket design and component selection. In recent years, there has been a tremendous increase in the prosthetic innovations and components available for the pediatric amputee. Knowledge of these components and their appropriate use will generally be the responsibility of a prosthetist with special interest and experience with children. In addition, he or she must possess the clinical skills, medical knowledge, and communication skills to timely direct the flow of knowledge to the other team members and parents, so that realistic expectations can be identified and achieved. Routine maintenance of the prosthesis is extremely important so that extensive repairs will be mini- mized and the need for a new prosthesis recognized. Children are generally not happy to be without their prosthesis. Fitting Techniques.  The technique will vary, on the basis of prosthetist experience, team philosophy, integration of ever-changing technology, and severity of the deficiency. Physiologically, the child is in a constant state of growth and the prosthetic device must be designed both to permit weight bearing and to allow for the greatest amount of growth ­without compro- mising fit and function. Most congenital lower extremity ampu- tees are able to bear some weight on the distal end of the residual limb, allowing the prosthetist to achieve a slightly less intimate fit of the prosthetic socket than might be the case for the acquired adult amputee. Unlike the adult, the child’s skin has greater toler- ance to skin breakdown. The increased activity levels of the child amputee place tremendous expectations on the prosthetic devices and the components. All of these factors are constant challenges to the prosthetic prescription and emphasize the need for a fluid approach to fitting. What may be suitable for one child may be