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Chapter 32 - Atlas of Limb Prosthetics: Surgical, Prosthetic, and Rehabilitation Principles Acquired Amputations in Children
Robert E. Tooms, M.D.
Annual surveys of specialized child amputee clinics in the United States have repeatedly shown that approximately 60% of childhood amputations are congenital in origin and 40% are acquired. In contrast, a survey of prosthetic facilities has revealed that significantly more children with acquired amputations receive prosthetic services than do those with congenital limb deficiencies. This discrepancy suggests that children with the more complex congenital limb deficiencies are referred to specialized child amputee clinics, whereas most acquired childhood amputations are managed in less specialized settings. In either case, the number of children with acquired amputations is relatively small but represents a significant segment of the pediatric population with major orthopaedic problems.
Acquired amputations are secondary to either trauma or disease, with trauma causing roughly twice as many limb losses as disease. Although there are obviously many traumatic incidents that may result in childhood amputations, power tools and machinery are the worst offenders, followed closely by vehicular accidents, gunshot wounds and explosions, and railroad accidents. In the older child, vehicular accidents, gunshot wounds, and power tool injuries are the most frequent causes of limb loss. In the 1- to 4-year-old group, power tools such as lawn mowers and household accidents account for most amputations (Fig 32-1.).
Of the disease processes necessitating amputation in children, malignant tumors are responsible for more than half, the highest incidence occurring in the 12- to 21-year-old group. Vascular malformations, neurogenic disorders, and a wide variety of miscellaneous disorders are responsible for the remainder of amputations due to disease (Fig 32-2.).
In over 90% of acquired amputations a single limb is involved, and it is a lower limb that is involved in 60% of the cases. Males outnumber females in incidence of acquired limb loss in a ratio of 3:2, most probably because males tend to engage in more hazardous activities.
SURGICAL PRINCIPLES
The well-established surgical principles for amputation surgery in the adult are just as applicable to amputations performed in children. The cardinal dictum in children is to conserve all limb length possible, consistent with appropriate treatment for the condition that requires the amputation. Trauma is the proximate cause of most acquired amputations in children. In attempting to conserve length in the severely traumatized limb, adequate tissue vascularity of the growing child may allow the surgeon to use surgical techniques that are not successful in the adult. Skin grafts, firm traction, and wound closure under tension may be judiciously used in the child to conserve limb length without compromising wound healing or subsequent prosthetic use. Split-thickness skin grafts, even over large areas of the stump, may tolerate prosthetic use quite well in the child. The increased elasticity of the child's skin coupled with an excellent blood supply allows the surgeon to apply somewhat heavier skin traction to open amputations in the child than would be safely tolerated in the adult. For the same reasons, open wounds may successfully be closed under slightly more tension in the child than would be permissible in similar adult patients. In each instance, however, good surgical judgment must be used since even the tissue tolerance of the child has its limitations.
A second surgical dictum is, whenever possible, to perform a disarticulation rather than a transdiaphyseal amputation in a growing child. Disarticulation preserves the epiphyseal growth plate and thereby ensures longitudinal growth of the bone. Loss of stump length due to epiphyseal loss is most readily apparent in trans-femoral amputations in young children. In amputations at this level, the distal femoral epiphysis, which accounts for approximately 70% of the longitudinal growth of the femur, is sacrificed. When a midthigh amputation is performed in a young child, the resultant stump present at 16 years of age will be quite short and will be a considerably less than optimal skeletal lever for prosthetic use (Fig 32-3.). Disarticulation also precludes the development of terminal or appositional overgrowth of new bone at the transected end of a long bone-the most common complication of amputation surgery in the growing child. The prominent condyles or malleoli resulting from disarticulation usually undergo atrophy with further growth of the child, thereby eliminating the cosmetic objection to this type of surgery when it is performed in the adult.
COMPLICATIONS
Terminal overgrowth is the most common complication of amputation surgery in the skeletally immature individual. This is an appositional overgrowth of new bone at the transected end of a long bone. It is in no way related to epiphyseal plate growth, and previous attempts to prevent this problem by epiphysiodesis have not been successful. Terminal overgrowth occurs most often in the humerus, fibula, tibia, and femur, in that order. In this condition, the appositional growth of new bone may exceed the growth of the overlying soft tissues to such an extent that the bone end actually penetrates the skin (Fig 32-4.). Many surgical techniques have been devised to prevent terminal overgrowth from developing. These include using intramedullary implants of silicone rubber or porous polyethylene to cap the resected bone end and prevent terminal overgrowth. This approach may eventually prove to be effective. However, the best treatment method remains stump revision with appropriate resection of the bony overgrowth. This has been necessary in 8% to 12% of several reported large series of acquired amputations in children. Once surgery becomes necessary to correct the problem, recurrences are common and may necessitate repeated stump revision at 2- to 3-year intervals until skeletal maturity.
Adventitious bursae frequently develop in the soft tissues overlying an area of terminal overgrowth. Conservative treatment of such symptomatic bursae by aspiration, corticosteroid injection, and stump wrapping is seldom more than temporarily effective. Bursae that form over bony prominences subjected to recurrent pressure from a prosthetic socket are effectively managed by appropriate socket modifications. Permanent relief from those symptomatic bursae overlying an area of terminal overgrowth usually requires surgical excision of the bursa combined with appropriate resection of the underlying bone (Fig 32-5.).
Bone spurs often form at the periphery of transected bone ends as a response to periosteal stimulation at the time of surgery. Such bone spurs rarely necessitate stump revision and should be easily distinguished from terminal overgrowth.
Extensive stump scarring from trauma, previous surgery, or skin grafting is usually well tolerated by the child amputee. Stump revision is seldom necessitated by scarring alone, but may require prosthetic modification to disperse weight-bearing forces and diminish shear stress at the stump-socket interface. Minor modifications in the prosthetic socket will usually relieve symptomatic pressure that is concentrated over small areas of scarring in relatively non-weight-bearing areas of the amputation stump. Wearing a nylon sheath next to the skin and beneath the stump sock or wearing multiple stump socks may prevent tissue breakdown from stump-socket interface friction over small areas of scarring. More extensive prosthetic modifications may be necessary when the scarred area is larger or is over weight-bearing areas of the stumps. Check sockets made of transparent polycarbonate plastic and stump socks of pressure-sensitive fabric allow precise identification of pressure-producing areas in the socket at both the transtibial and the transfemoral amputation levels. For the severely scarred transtibial stump, the most commonly used method of relieving excessive pressure and shear forces is attaching outside knee joints and a weight-bearing thigh corset to a total-contact socket. Other successful techniques include the use of an air cushion socket or a Silastic gel socket insert with a rubber sleeve for suspension. I have been most successful in eliminating skin breakdown in the extensively scarred transtibial stump by using a meticulously fitted hard-socket patellar tendon-bearing (PTB) prosthesis worn over two or three five-ply stump socks. Suspension is by means of a supracondylar strap or, if necessary, with outside knee joints and a thigh corset.
When upper-limb amputations are complicated by extensive trunk scarring, harnessing techniques alternative to the figure-of-8 harness may be necessary. The shoulder saddle with chest strap is an excellent solution in such cases (Fig 32-6.).
Neuroma formation in amputation stumps of children is seldom symptomatic enough to warrant surgical treatment. In reviewing a large series of acquired childhood amputations, Aitken found that only 4% required surgical treatment for neuromas, most being satisfactorily managed by socket adjustment.
The phantom limb phenomenon always occurs in children following acquired amputations. If the amputation is performed on a child under the age of 10 years, the phantom sensation is rapidly lost. Painful phantom limb sensation does not occur in growing children, but has been reported in the teenager.
SURGICAL TECHNIQUES
Except for the previously discussed surgical principles of limb length conservation and the need for performing disarticulations in preference to transdiaphy-seal amputations, surgical techniques in the child do not differ significantly from those used for the adult. Therefore specific surgical procedures will not be outlined for any of the major levels of amputation in the upper or lower limb. However, several specialized surgical procedures do deserve mention.
The Krukenberg, or "lobster-claw," operation, may well deserve consideration in the child with a long transradial (below-elbow) amputation. The Krukenberg procedure provides a crude pinching mechanism with preserved sensation by splitting a long transradial stump into radial and ulnar rays that are widely separated and covered with skin possessing normal sensation. The forearm muscles that attach to the two rays provide voluntary opening and closing of these rays. Children who have the operation performed early in life learn to use the pincer and are not often emotionally disturbed by the unsightly appearance of the stump. The procedure has its greatest application in bilateral upper-limb amputees, especially in the blind.
Syme ankle disarticulation is a frequently indicated level of amputation in the growing child. It should be stressed that this procedure should be performed as a true disarticulation with a Syme-type soft-tissue closure and not as a supramalleolar amputation as is done in the conventional ankle disarticulation in the adult.
Lawn mower injuries and severe burns that result in partial limb loss occur in sufficiently large numbers to justify specific comments on the surgical management of these problems. As in other traumatic incidents, preservation of limb length is of major concern in both of these injuries. The physiologic tolerance of growing children fortunately allows the surgeon to preserve limb length by using skin grafts, traction, and soft-tissue-shifting plastic surgery procedures.
Most lawn mower injuries sustained by children result in partial-foot amputations. Some of these injuries involve only the digits or the distal metatarsal area and present no great treatment problems. Others are quite extensive and involve most of the foot with multiple deep and extensively contaminated wounds. In these latter instances, proper surgical judgment is necessary to determine which injury can reasonably be expected to provide a serviceable partial-foot amputation by using skin grafts and soft-tissue-shifting plastic surgery procedures and which injury would require revision to a higher level. This decision is seldom obvious, and when doubt exists, it is better to err on the side of conservatism. The initial debridement of such injuries should be limited to excision of only that tissue that is absolutely nonviable, with any tissue of questionable viability being preserved. Initial bone resection should be minimized until sufficient time has elapsed to be certain how much viable soft tissue will ultimately be available for wound closure. Following thorough irrigation and debridement, the wound is lightly packed open.
Five to 7 days later the wound is examined with the patient under anesthesia. After further debridement of any nonviable tissue, a decision may be made to revise the amputation to a higher level or to continue with a more conservative approach. For example, an amputation at the midtarsal joint level that requires extensive skin grafting over the plantar surface of the heel and results in a loss of the foot dorsiflexors will be less functional and require more subsequent treatment than will revision to a higher level. If revision to a higher level (Syme ankle disarticulation or transtibial amputation) is indicated at the time of the first wound dressing, an open amputation is preferable, followed by skin traction until secondary closure is performed 5 to 7 days later. If continued conservatism seems appropriate, it may be possible to partially close the wound at this time with minimal additional bone resection. If extensive skin grafting or tissue-shifting plastic surgery procedures such as a Z-plasty are needed, these are more safely done at the time of a second wound dressing 5 to 7 days later, when granulation tissue begins to cover open areas and the danger of infection is less.
Thermal or electrical burns may cause such widespread tissue destruction that amputation of a major portion of the limb may become necessary. In such circumstances, conservative treatment should be pursued until there is adequate demarcation of nonviable tissue to allow open amputation at the lowest possible level. During this time, appropriate splinting of proximal joints is essential to minimize the development of joint contractures in nonfunctional positions. Despite splinting, late soft-tissue releases may be needed to improve joint motion. Extensive skin grafting is usually necessary in children with severe burns, and the resultant scarred stumps may present very difficult problems in prosthetic fitting. The use of pressure dressings over scarred and grafted areas helps to decrease scar hypertrophy. When healing has occurred, gentle massage is often beneficial in mobilizing scar tissue that is adherent to bone. Successful prosthetic use usually necessitates modification of prosthetic sockets and suspension systems as noted previously.
References:
- Aitken GT: Overgrowth of the amputation stump. Inter-Clin Info Bull 1962; 1:1-8.
- Aitken GT: Surgical amputation in children. J Bone Joint Surg [Am] 1963; 45:1735-1741.
- Aitken GT: The child with an acquired amputation. Inter-Clin Info Bull 1968; 7:1-15.
- Aitken GT, Frantz CH: Management of the child amputee. Instr Course Lect 1960; 17:246-298.
- Aitken GT, Frantz CH: The juvenile amputee. J Bone Joint Surg [Am] 1953; 25:659-664.
- Brand PW, Ebner JD: Pressure sensitive devices for de-nervated hands and feet. J Bone Joint Surg [Am] 1969; 51:109-116.
- Cary JM: Traumatic amputation in childhood-primary management. Inter-Clin Info Bull 1975; 14:1-10.
- Davies EJ, Friz BR, Clippinger FW Jr: Children with amputations. Inter-Clin Info Bull 1969; 9:6-19.
- Frantz CH, Aitken GT: Management of the juvenile amputee. Clin Orthop 1959; 9:30-47.
- Hall CB, Rosenfelder R, Tabloda C: The juvenile amputee with a scarred stump, in Aitken G (ed): The Child With an Acquired Amputation. Washington, DC, National Academy of Sciences, 1972.
- Herndon JH, LaNone AM: Salvage of a short below-el-bow amputation with pedicle flap coverage. Inter-Clin Info Bull 1973; 12:5-9.
- Kay HW, Fishman S: 1018 Children With Skeletal Limb Deficiencies. New York, New York University Post-Graduate Medical School, Prosthetic and Orthotics, 1967.
- Koepke GH, Giacinto JP, McUmber RA: Silicone gel be-low-knee amputation prostheses. Univ Mich Med Center J 1970;36:188-189.
- Lambert CN: Etiology, in Aitken G (ed): The Child With an Acquired Amputation. Washington, DC, National Academy of Sciences, 1972.
- Meyer LC, Sauer BW: The use of porous high-density polyethelyne caps in the prevention of appositional bone growth in the juvenile amputee: A preliminary report. Inter-Clin Info Bull 1975; 14:1-4.
- Romano RL, Burgess EM: Extremity growth and overgrowth following amputation in children. Inter-Clin Info Bull 1966; 5:11-12.
- Snelson R: Use of transparent sockets in limb prosthetics. Orthot Prosthet 1973; 27:3.
- Swanson AB: Bone overgrowth in the juvenile amputee and its control by the use of silicone rubber implants. Inter-Clin Info Bull 1969; 8:9-16.
- Swanson AB: Silicone-rubber implants to control the overgrowth phenomenon in the juvenile amputee. Inter-Clin Info Bull 1972; 11:5-8.
- Swanson AB: The Krukenberg procedure in the juvenile amputee. J Bone Joint Surg [Am] 1962; 46:1540-1548.
- Von Soal G: Epiphysiodesis combined with amputation. J Bone Joint Surg 1939; 21:442-443.
- Wilson LA, Lyquist E, Radcliffe CW: Air-cushion socket for patellar-tendon-bearing below-knee prostheses. Bull Prosthet Res 1968; 10:5-34.
Chapter 32 - Atlas of Limb Prosthetics: Surgical, Prosthetic, and Rehabilitation Principles
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