Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

is used exclusively for this level of amputation because of an increased level of cosmesis and decreased weight. Children with ­amputations at this level can achieve remarkable gains when fitting begins while the child is pulling to stand and when therapeutic intervention and parental training are incor- porated. It is recommended that the knee be locked, initially, so that hip control can first be learned. Once the child is walk- ing independently, the knee can be activated. Transfemoral Prosthesis.  Transfemoral socket design has evolved significantly over the last 10 years. The quadrilateral socket was the socket design of choice until 1987, when the ISPO formulated recommendations on the narrow medial lateral (ML) socket design (221). Variants of this design (ischial containment socket) continue, including the contoured adducted trochan- teric-controlled alignment method (CAT-CAM), the normal shape, normal alignment, and the modified quad designs, to name a few (Fig. 30-45). The underlying principle is to adduct the femur while locking the ischial tuberosity within the socket, thereby providing a more anatomically correct alignment during all phases of gait (222). The controversy over these designs has been increasingly dispelled, with further clinical experience. There are various suspension mechanisms that may be utilized for the secure attachment of the socket to the residual limb. These devices may provide auxiliary suspension which is attached to the socket to suspend or enhance suspension. The suspension may be incorporated in the socket itself, as in suc- tion sockets, SC sockets, and so on. Pediatric amputees are usually fitted with a Silesian belt system of suspension (Fig. 30-46A,B), until adequate devel- opment of the residual limb allows for silicone suspension, at approximately 2 to 3 years of age. The Silesian belt attaches to the anterior/medial aspect and the lateral aspect of the transfemoral socket and lies across the pelvis at the waist. Tightening the Silesian belt prevents the socket from slipping distally. The TES belt may be used instead of the Silesian belt. The TES belt is a neoprene suspension system that is applied over the proximal portion of the ­transfemoral socket and is then secured around the waist, and it has become the suspen- sion of choice for the first-time ­prosthetic user.

aid the infant in preparation for ambulation, transitioning from crawling to standing, with little consideration of gait at this point. Sutherland concluded that mature gait pat- terns were established by 3 years of age (219), whereas others place the time frame closer to 6 years of age. Early infant gait patterns are, in fact, the processes of suppression of primi- tive reflexes and the acquisition of postural responses (220). Dynamic alignment is the manipulation of relative position of the socket to the foot and knee while the prosthesis is moving through the various stages of gait. Through the use of align- ment mechanisms in the components, the prosthetist is able to shift, tilt, and rotate the knee and foot in relation to the socket. Once independent gait is established in the infant, refinement to gait can be achieved through further prosthetic alignment. Lower Extremity Socket Design.  The design and fitting of lower extremity prostheses encompasses numerous biomechanical principles and their application to the residual limb–socket interface, and it is the successful manipulation of these forces that ensures a patient’s comfort and function. The accommodation for differences in tissue compressibility, pressure tolerance, underlying bony structures, and vascular integrity are factors taken into account prior to socket design. Dynamic forces exerted through ground reaction forces and resulting moments, including torque and shear forces, increase the vulnerability of the skin–socket interface. Hip Disarticulation.  Amputees at the hip disarticulation level require extensive prosthetic intervention. The socket encompasses the amputated pelvic remnant and encloses the contralateral side for suspension. The traditional socket design rises proximally to the waist and fits similarly to a Boston spinal orthosis. The diagonal socket is a modified version of the standard design, and it affords a more comfortable fit and increased flexibility. Prosthetic hips arc on a single axis and are mounted on the outside anterior distal aspect of the affected side. Hip and knee flexion are easy to activate through pelvic tilt, if the prosthesis is perfectly aligned. The hip is anterior to the weight line and the knee is posterior. This allows for a stable stance and a smooth gait. The endoskeletal system

FIGURE 30-45. A : The quadrilateral socket is useful for the young child, especially if end bearing is possible. However, it fails to stabilize the femoral segment in a transfemoral amputation. B : This has led to the popular- ity of the narrow ML socket design, such as the ischial containment socket shown here. This design can prove impossible in small infants, because of the fatty thigh and buttocks as well as the diapers.

Bony lock

Counter force

B

A