Weinstein Lovell and Winters Pediatric Orthopaedics 7e

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CHAPTER 30  |  The Child with a Limb Deficiency

Comparison of Myoelectric with Body-powered Prostheses

TABLE 30.4

Myoelectric

Body-powered

Weight Heavier; passive prostheses are weighted to prepare the patient for the myoelectric system Grip Strength Stronger than a body-powered prosthesis; strength built into the system; less work for the child Cosmesis More accepted; resembles the hand; more self-esteem for the child; greater parental acceptance Maintenance Requires gloves; requires maintenance and ­electronics; electrodes lose contact and require occasional adjustment; ­adjustments required for growth Harness No harness or straps on body; suspension through socket

Weight spread across the shoulders

Strength is provided by rubber bands that increase or decrease the tension and force needed to open the hand; more work needed through scapular control Hooklike or clawlike in appearance; usually rejected by the child or parent; object of ridicule by other children Requires gloves if mechanical hand is used; frequently requires repair for broken cables caused by friction; requires ­adjustments for growth on a regular basis Harness is bulky on a toddler, difficult to keep on without ­pinning to undergarment; children dislike harness especially in summer months Uses muscles distant from the terminal device, biscapular abduction to control hand or hook; very confusing for toddler whose control and balance is developing; easier for older children Toddlers lose grip very easily, overall gross movements allow the object being grasped to release and fall involuntarily; tension on the cable to the harness does not remain ­constant; becomes very frustrating for the child

Muscle Control Uses muscles in limb to control terminal device; with prosthetic hand, the child can experience direct “cause and effect”

Grip Control Maintains grip more easily through muscle ­contraction at the end of the residual limb; is the most successful type of ­control

FIGURE 30-40. A : Preoperative clinical photograph of a patient with a transverse forearm deficiency. B : Intraoperative photograph during the Krukenberg procedure. The muscle in the Alis clamp is the pronator teres, which will function during pincher grasp. C : Intraoperative photograph at the end of surgery. Split-thickness skin grafts are necessary to complete skin closure.