Limb deficiencies (lds) in children are an example of the complexities of embryologic, physical, and emotional development. The two broad categories of LDs are congenital and acquired amputations. Congenital defects are often associated with other nonmusculoskeletal anomalies; these can be dictated by genes or caused by stressors during fetal development. “Acquired amputations” refer to limb loss that occurs after birth. Acquired amputations may be secondary to cancer, infection, or trauma. Unlike the adult population, the residual limbs are not static; growth and development create the potential for complications¹ (Fig. 59–1).

The care of children with LDs requires a multidisciplinary approach. This chapter focuses on medical, functional, and rehabilitation issues of both congenital and acquired LDs in children.

Classification and nomenclature attempt to categorize LDs by the use of a descriptive method focusing on anatomic and phenotypic findings despite the etiology. Greek and Latin names were often used to describe congenital LDs. Terms such as hemimelia, meromelia, and phecomelia have been deemed inaccurate and are often confusing. Since the 1960s, several attempts have been made to improve this terminology.^2–7 Consensus was reached, and an international terminology was established by the International Society for Prosthetics and Orthotics (ISPO).^6,8 The ISPO classification creates a logical, accurate approach to naming congenital LDs (Fig. 59–2). It focuses on dividing all deformities into transverse or longitudinal. A transverse deficiency has no distal remaining portions, whereas the longitudinal deficiency has distal portions. The transverse level is named after the segment beyond which there is no skeletal portion. Longitudinal deficiencies name the bones that are affected, beginning with the most proximal long bone. Any bone not named is presumed present and of normal form. The affected bone is designated as total or partially absent. The approximate fraction of the limb in a transverse deficiency is estimated in thirds, whereas the longitudinal deficiencies describe a partial or complete bone absence. Involved digits are then identified. Digit numbering proceeds from the radial or tibial side of the limb. “Ray” refers to the metacarpal or metatarsal and corresponding phalanges.

The terminology used for acquired amputations follows the convention for adult limb loss, as shown in Figure 59–3.

Congenital LDs

Birth defects occur in approximately 3% of all live births, and 6% of all types of birth defects are LDs, which account for 60% of all pediatric amputations. According to some national registries, the prevalence of LDs varies between 3 and 12.8 per 10,000 births.^3,9 The upper-to-lower LD ratio is 2:1, and the left-to-right-side ratio has been estimated at 1.2:1.^10,11 Longitudinal defects are more common than terminal transverse defects.³ Although some of these babies will have both upper and lower limb-reduction defects, unilateral deficiencies are four times more common than bilateral deficiencies.¹⁰

Advances in prenatal diagnostic tools have resulted in an earlier diagnosis of LD.^12–15 Diagnosis of congenital LDs and reductions may be performed in utero with ultrasonography.^16–19 Other tests such as amniocentesis and chorionic villous sampling also help reveal syndromes associated with LDs. The information from such studies is essential because prenatal counseling provides better education for women and families who are faced with the diagnosis of a fetal structural anomaly.¹⁸

Acquired LDs

Trauma causes limb loss twice as often as disease. The overall rate for children admitted to US hospitals with a diagnosis of traumatic amputation is estimated at 1.32 cases per 100,000 children aged 0 to 17 years.²⁰ Males experience more than half of these injuries. Finger and thumb amputations account for the vast majority of all traumatic amputations, with a bimodal distribution on groups 0 to 2 years of age and 13 to 17 years of age. More than 50% of traumatic amputations are complete amputations. Adolescents have the highest proportion of amputation injuries involving lawn mowers and/or tools. The percentage of amputations involving doors peaked in the youngest age group and decreased as age increased.²¹ Motor vehicle accidents accounted for 16% of all injuries; 77% of these ultimately had amputations.²²

Other causes of traumatic LDs vary by region. In rural areas, accidents involving farm work, lawnmowers, and high-tension wires are the primary causes. Other etiologies may include gunshot wounds, vehicular accidents, burns, power tools, and boating accidents. In regions of war and conflict, blast injuries and gunshot wounds are more common as causes of LDs. Traumatic amputations may also occur in areas of natural disasters with an equal ratio between children and adults. Disease causes of acquired amputations include vascular syndromes, infections, and posttumor resections.

Osteosarcoma is the most frequent bone cancer occurring in children and adolescents aged 10 to 20 years, whereas in children younger than 10 years, the most common primary bone cancer is Ewing’s sarcoma.²³ Osteosarcomas most often occur near the metaphyseal growth plates of the long bones of the extremities. The most common sites are the distal femur, the proximal tibia, and the proximal humerus.²³ The goal of surgery is a disease-free limb that is optimal for prosthetic fitting.

Chemotherapy and radiation are often used in the oncology population before or after amputation. Complications of these, such as peripheral neuropathy, may result in pain and discomfort that may interfere with prosthetic fitting. Ultimately, tumor-related amputations are a result of surgical resection.

Amputations from infection and vascular complication are less common in children. Infectious emboli may autoamputate limbs or digits. Meningococcal infection is well known and frequently involves all extremities. Meningococcemia affects as many as 3,000 patients annually, with the highest incidence in children younger than 2 years of age.²⁴ Children younger than 5 years of age account for two-thirds of meningococcal cases; this is attributed to their immature immune systems.²⁴ Growth plates may be affected, resulting in angular deformity and the need for surgical epiphysiodesis.²⁵ Because the skin is affected as well as the limb, there may be the need for multiple surgical skin grafts.^24,26–28 Other infections such as pneumococcal septicemia can produce purpura fulminans, characterized by acute onset of rapidly progressive hemorrhagic necrosis of the skin and thrombosis.²⁹

Similar to LDs caused by infections, LDs secondary to vascular events are uncommon in children. Antiphospholipid syndrome may result in vascular complications (similar to those of infectious etiologies).³⁰ As advances in medicine allow for survival of infants with complex cardiopulmonary defects, the incidence of amputations in children with congenital heart and lung disease may increase. In adults, the use of extracorporeal membrane oxygenation comes with a risk of amputations.^31–33 The incidence and management of these complications in children are yet to be examined.

Congenital

Limb genesis is a complex embryologic process initiating with genetic composition and continuing until birth. The mesoderm formation of the limb occurs at 26 days’ gestation and continues with differentiation until 8 weeks’ gestation. The various limb segments develop in a proximal-to-distal order, with the upper extremity developing prior to the lower extremity.

Numerous genes have been identified to play a role in bud development.³⁴ Although a small set of these genes is inherited, more than 80% of heritable. LDs are associated with more systemic and nonmusculoskeletal anomalies. Almost 50% of lower LDs have associated abnormalities such as chromosomal irregularities or other syndromes. Additional birth defects have also been seen in 60% of children with upper LDs.³⁵ Of children born with LDs, 57.9% have associated malformations³⁶ (Table 59–1).

Malformations in the cardiac system, the genital system, and the central nervous system (CNS) are the most common malformations, followed by malformations in the renal system and the digestive system. The overall prevalence of associated malformations is more than 1 in 2 infants.³⁶ Therefore, routine follow-up by these disciplines is necessary.

Once the fetus has formed, stressors during the gestational period such as uterine abnormalities and drug and environmental exposures result in other congenital LDs. In 2001, McGuik et al estimated that 34% of congenital limb deficiencies are due to vascular disruptions and 5% are due to teratogenic exposure. Thirty percent had a genetic component, and the etiology is unknown for the remaining 32%. Amniotic bands are frequently implicated, especially in transverse upper LDs. The environment for development must also be optimal for successful limb development. Maternal conditions such as diabetes (including gestational diabetes) have been shown to increase the risk of LDs. In the 1960s, the use of thalidomide was well recognized as a cause of congenital LDs.³⁷ In many countries, the use of this medication was regulated after the teratogenic revelation. Despite attempts at regulation, congenital defects from maternal ingestions continue to be reported in other countries.^38–40

Maternal ingestions of certain drugs such as valproic acid and calcium channel blockers have also been shown to have a negative effect.^41,42 The fetus is most vulnerable in the first trimester. Smoking increases the risk of digit anomalies.⁴³ Maternal occupation may play a role, with exposure to chemicals, as in the agricultural setting.^44,45 As the fetus grows, uterine abnormalities may apply pressure on the fetus and intervene with its development.⁴⁶ Prenatal vitamins reduce the risk of limb deficiencies.⁴⁷

Other forms of congenital limb reductions may require management similar to LDs. Proximal femoral focal deficiency (PFFD) is an uncommon congenital condition manifested by hypoplasia of part or the entire proximal femur that presents as a shorter limb during infancy. PFFD encompasses a spectrum from hypoplasia of the femoral head to congenital absence of all but the distal femoral epiphysis. PFFD is unilateral in 90% of cases.

Arthrogryposis is another syndrome with limb reductions. This condition refers to multiple congenital contractures that may affect two or more areas of the body; in some cases it affects all four limbs.⁴⁸ The overall prevalence is 1 per 3,000 live births. Etiology of this clinical finding may vary, and some may be severe enough to result in death.⁴⁹

Surgical Planning

Surgical evaluation and treatment of acquired and congenital LDs attempt to achieve an optimal residual limb that is both free of disease and optimal for prosthetic fitting. In acquired LDs, adherence to the general principles of childhood amputation surgery guides one to optimal function. Surgical management for upper extremity LDs is uncommon. Hand surgical procedures, specifically restoring thumb function, can allow for better opposition, prehension, and grasp. Pollicization can occur to the most radial digit in order to provide oppositional grasp.⁵⁰ Toes can be transplanted from the second or third ray and minimize effects on gait mechanics.^50–54 Ligation of polydactyly has been associated with complications of infection, gangrene, and residual sensitive skin tags.⁵⁵ Therefore, functional benefits must be considered before surgical intervention is introduced.

The principles are (1) preservation of bone length, (2) preservation of important growth plates, (3) perform disarticulation rather than transosseous amputation, (4) preserve the knee joint whenever possible, and (5) stabilize and normalize proximal portions of the limb.⁵⁶ Following these stated principles for lower extremity amputation allows for a better gait pattern, less metabolic energy consumption, and improved functional capacity during ambulation.^57,58

The cardinal surgical dictum to conserve all limb length if possible is true for children as well as adults. In growing children who require amputation, disarticulation rather than a transdiaphyseal amputation may be preferred.⁵⁹ Disarticulation preserves the epiphyseal growth plates and ensures longitudinal growth.⁵⁶ Disarticulation also avoids the development of terminal or appositional overgrowth of new bone.

Congenital LD management is challenging. There is often need for surgical intervention to correct deformities and provide a more functional residual limb. There are a few common congenital lower extremity LDs that require surgical revision.

Longitudinal deficiency of the fibula presents as an absent fibula, shorter tibia, and often ipsilateral short femur. A common complication observed in this LD is anterior bowing of the tibia. The anterior prominence is seen as a subcutaneous dimple. Proximally, the limb is often in genu valgum; this deformity becomes more obvious as the child grows. The distal involvement is usually an equinus position and a valgus posture during weight bearing due to the lack of lateral support. Lateral tarsal and ray absences are often associated with this lateral long bone absence. As the child grows, the popliteal area becomes convex, with the medial hamstrings descending much lower than the lateral hamstrings. External hip rotation often results. A classification system by Birch et al takes into consideration the functionality of both the foot and the upper extremities as well as the percentage of limb-length discrepancy.⁶⁰ This classification outlines a guide for treatment for each group.

The goals of management are to achieve normal weight bearing and, in addition, to equal limb length. Management of congenital fibular deficiency (CFD) is based on foot functionality and leg-length discrepancy, not fibular morphology.⁶¹

The most common surgical interventions for this deficiency are Syme and Boyd amputations, which are successful in providing an end-bearing surface for ambulation (with or without a prosthesis).^61,62 To avoid interference with the normal developmental milestones of the child, amputation takes place when the child is beginning to pull to stand. In addition to the ankle disarticulation procedures, it may be necessary for the child to undergo unilateral epiphysiodesis or angulation osteotomies if the genu valgum becomes a prosthetic challenge to fit. Limb-lengthening procedure may also be performed to achieve limb-length equality. As adults, individuals with congenital deficiency of the fibula who undergo limb lengthening versus amputation have been found to be more highly functional with an above-average quality of life. Individuals with an amputation spent less of their childhood undergoing treatment, and they were found to have a better outcome in terms of only one of seventeen quality-of-life parameters.⁶³

Two forms of femoral abnormalities have been described: congenital short femur (CSF) and proximal femoral focal deficiency (PFFD). In CSF, the proximal aspect of the femur and ipsilateral acetabulum are intact. The labrum is present, resisting hip subluxation. Clinical findings of PFFD include a shortened thigh segment that is typically held in a flexed, externally rotated, and abducted position. Imaging demonstrates significant shortening of the femoral segment that is often accompanied by other abnormalities in the proximal femur, including coxa vara, presence of a pseudoarthrosis, and acetabular dysplasia. Despite anatomic deformities of the ipsilatera hip and femur in PFFD, the joint is relatively stable. Surgical stabilization is controversial. Fibular absence is also often encountered.

Classification methods such as the Aitken classification attempt to categorize the pathology based on the degree of shortening and anatomic deficiencies of the proximal femur (Aitken G. Proximal focal femoral deficiency, definition, classification, and management. In: Aitken G, ed. Proximal focal femoral deficiency: a congenital anomaly. Washington, DC: National Academy of Sciences; 1969: 1–22). Other clinically based, treatment-oriented classification schemes have been proposed as well.⁶⁴

Treatment of such deformities vary. In cases where there is no surgical intervention, a shoe lift or “prosthoses” may correct the leg-length discrepancy. A prosthoses is a combination of a proximal orthoses with a distal prosthetic component. Application of an external fixator to lengthen the femur may be considered. Additional timed epiphysiodeses to the contralateral leg may halt growth of that limb and decrease the length needed to be reached by the involved limb. In more involved cases, ankle disarticulation with knee arthrodesis is performed. Current opinion advocates the use of surgery in the management of PFFD. It is thought to have better cosmetic and functional results, but a study by Kant et al reveals that as adults, patients managed by nonsurgical extension prosthesis versus surgery had similar scores for mobility. The nonsurgical approach was associated with fewer musculoskeletal and residual limb problems, fewer problems with public transport, and greater satisfaction than Syme amputation.⁶⁵

In patients in whom the distal femur is affected and the knee joint is no longer salvageable, the Van Ness rotationplasty is considered. The procedure involves rotation of the foot 180 degrees through removal of the distal femoral and proximal tibial epiphyses and rotation of the distal segment prior to internal fixation.^53,57 The rotated foot can now act as a knee, using ankle dorsiflexion as knee flexion and ankle plantar flexion as knee extension. An intact fibula is preferred for this surgical procedure. This procedure is used in disorders such as burns, osteosarcoma, or other femoral growth abnormalities.

Longitudinal deficiency of the tibia is a far less common LD. The tibia is a major weight-bearing bone. The clinical presentation of a longitudinal tibial deficiency may include a varus foot and lower leg, a short leg, and an unstable knee and ankle. Rays may also be missing. Distal femoral bifurcation not only coorrelates with greater genetic transmission but also may add to the challenge of prosthetic fitting. When there is a complete absence of the tibia, the treatment of choice is disarticulation at the knee. The fibula cannot sustain weight bearing of the individual as he or she grows. For the child with a partial tibial deficiency, the surgeon creates a synostosis with the intact fibula in conjunction with amputation of the foot. The heel pad creates a walking surface for the child, providing stability without a prosthesis. If there is too much leg-length deficiency, the residual limb is treated as a transtibial amputation. Lateral bowing is a common complication for this LD, resulting in a prominent fibular head that complicates socket fitting.

Complications

Bone Growth

Terminal overgrowth at the transected end of the long bone, often referred to as “spiking,” is a common complication after amputation in an immature child.^66,67 The rate of occurrence has been estimated at 4% to 43%. The mean time of occurrence is over 40 months after the original amputation. Terminal bone overgrowth is more common in the lower than upper extremities.⁶⁸ Metaphyseal-level amputations are 50% more likely to develop spiking than diaphyseal-level amputations. Disarticulations never encounter this phenomenon. During appositional growth, the distal bone begins to form in the shape of an icicle. As the pointed segment creates insult to the soft tissue, a bursal formation often occurs to protect the distal residuum. During this time, the child may experience significant pain and be unable to tolerate wearing a prosthesis. Radiographic imaging may be used to grade the degree of severity.⁶⁹

Frequent socket modifications are necessary to accommodate these anatomic changes. Treatments such as aspiration, steroid injections, and residual limb wrapping are usually ineffective. Unfortunately, the rate of growth may be so vigorous that the bone pierces the skin; at this stage, the treatment of choice is surgical revision. Distal resection and residual limb capping with the use of autografts or plastic polymers are surgical options.⁷⁰ Other surgical intervention such as the modified Ertl procedure have been investigated but found to not be beneficial in skeletally immature patients.⁷¹ Traumatic amputations are more likely to require surgical revision for this complication. Revisions are usually not required if the age at amputation is greater than 12 years or in cases of disarticulation.⁷² Once surgery becomes necessary, the problem is likely to recur until skeletal maturity. Each time that bone is resected, the overall length of the bone is reduced, thereby affecting its mechanical advantage and potential control of the prosthesis. Bone spurs may form at the periphery of the transected bone, and resection may be necessary. The resulting residual limb scarring, which interferes with weight bearing, requires prosthetic modifications. Plastic surgeons are involved with reconstruction of skin flaps or with complicated repairs of residual limbs.^73,74

Phantom Sensation and Phantom Pain

An individual’s awareness of the missing limb is known as “phantom sensation.” This is often not painful or unpleasant. Children with congenital deficiencies do experience phantom sensation, although it is not painful.⁷⁵ Phantom sensation in children with limb deficiency is explainable if we recognize the brain as a generator of sensory information.⁷³ Phantom limb pain rarely occurs in children under age 10 or during growth but is reported in teenagers.⁷⁶ In addition, children with congenital limb deficiencies are less likely to experience phantom sensations than those with acquired amputations.^77,78 In tumor resection amputations, phantom sensation and pain are more common.

Management of phantom limb sensation is warranted when pain is present and when it affects function or quality of life. Several medications have been studied in adults, and results are anecdotal in children.

Neurologic, neurophysiologic, and psychopathologic approaches to treatment may be helpful. Treatments such as mirror therapy have been effective in older children.⁷⁹

Other Complications

The presence of a distal tibia-fibula synostosis in pediatric amputee patients may contribute to the risk of developing a progressive varus deformity and should be monitored during the child’s growth. Distal tibiofibular synostosis may disrupt normal differential longitudinal growth and may contribute to this progressive angular deformity. Severe deformity may require prosthetic modifications or operative correction to provide for a normal mechanical axis. Lateral hemiepiphyseodesis of the proximal tibia can be effective if the deformity is detected early. We do not recommend creation of a synostosis in a young child for terminal growth.⁸⁰

Leg-length discrepancies after amputations are common. During growth, these must be monitored. Significant discrepancy can affect gait and prosthetic fitting.^26,63,81

Prosthetic Management

Upper Extremities

Arms explore the environment in infancy. As the child ages, arms and hands allow reaching, grasp and release, and manipulation of objects. Hand replantation is accepted treatment due to the better functional and aesthetic outcome than other nonsalvage procedures.^82–85 Exposed skin is preferred over prosthetically encumbered or encased limbs. A prosthetic device acts as a mechanical tool, but it will not replace sensory function. Acceptance of upper extremity prostheses is variable; the more proximal the limb deficiency, the less compliant children are.⁸⁶ In addition, the parents’ acceptance of the LD is crucial.

Digital Deficiencies

Digital deficiencies are common but rarely present in isolation. When introducing upper extremity prostheses, there is a balance to be reached between function and intact sensation. Consideration has to take into account abnormalities.

Partial Hand and Wrist Deficiencies

Partial hand deficiencies are common and function as a wrist disarticulation. Lack of thumb opposition results in loss of prehensile task with the involved limb. Nubbins (small, underdeveloped vestigial digits) are often present. They are rarely problematic and often retained.

Transverse Forearm Deficiencies

Transverse deficiencies of the forearm are the most common major LD. A transradial or below-the-elbow amputation will result in similar functional outcomes. Ipsilateral humeral shortening and the presence of smaller nubbins are common. Surgical intervention in this cohort is controversial.^87,88 In shorter residual forearm, a common complication is proximal radius instability; resulting in anterior subluxation during full extension. This creates a challenge to prosthetic fitting. The longer residual limbs, in the middle third of the forearm, tend to be more easily fit with prostheses because they have more surface area over which to distribute the forces of the socket interface and have longer lever arms with which the patient can control the prosthesis.

If prosthetic intervention is not attempted or accepted, bimanual tasks will be performed via adapted grasping of objects in the cubital fold, between one’s legs, in the axilla region, or under the chin.

Longitudinal Forearm Deficiencies

Depending on the classification of the radial deficiency, prehensile capabilities may be compromised by a hypoplastic or absent thumb. In these situations, pollicization or toe-transfer procedures are often discussed. Treatment for radial deficiencies is focused on reconstructing the thumb.

With ulnar-side involvement, the thumb and another digit are usually present, allowing for grasp function without the need for intervention. In central ray syndrome, commonly referred to as “lobster claw,” the central components of the hand and/or foot are absent. This can present as a mild condition, with the more ulnar and radial digits still present, or it can present as two longer and thicker digits. Functional abilities with this condition will vary. Many individuals will not need prosthetic restoration because the limbs are at full length and have prehensile and tactile capabilities. Surgical reconstruction is recommended if the child lacks the oppositional capabilities that the thumb usually offers.

Elbow and Transhumeral Deficiencies

As more articulations are involved, function declines. The true elbow disarticulation limb has the distal epiphysis present, which is important to overall growth of the residuum. A drawback of any disarticulation is the lack of room to fit prosthetic components and maintain humeral length equality.

In transhumeral deficiencies, the residual limbs are often medium to short in length. In addition, this level of deficiency has been previously noted as the most common to experience diaphyseal overgrowth. This leads to a short, nonfunctional residuum when multiple surgeries have been completed.

Longitudinal Humerus Deficiencies

When a longitudinal deficiency of the humerus is present, it is often associated with deficiencies in the radius, ulna, and digits. Because the arm is shorter, this leads to a smaller work area when attempting to perform bimanual tasks. Prosthetic fitting is frequently offered at this level compared with longitudinal deficiencies of the forearm. The shoulder complex is often compromised. Therefore, if the child were to be fit with a prosthesis, a creative approach must be entertained. The child would most likely receive some externally powered components using residual digits to manipulate those components.

Shoulder and Intrascapulothoracic Deficiencies

It becomes increasingly difficult to restore the functions of the anatomic arm as the level of deficiency reaches the shoulder and higher. Children with remnant humeri have the ability to use these segments to assist in their activities. Holding and manipulation of objects require more imagination. These children often rely on holding objects in the mouth or trapped between chin and chest or chin and shoulder.

In bilateral deficiencies at the shoulder level, the child will be strongly encouraged to use his or her feet to grasp and manipulate objects.

Most of the body movements or excursion required to operate an upper extremity prosthesis is not present at the shoulder disarticulation level because glenohumeral flexion no longer exists as a source of control input. The more proximal the LD, the fewer movements are available for manipulation of the device. Because there is a lack of significant functional improvement, compliance with prosthesis use at this level is poor.

Prosthetic Intervention and Adaptive Equipment for Upper Extremities

Upper extremity prosthetic fittings will be limb-level dependent. As in adults, options vary between passive, body-powered, and externally powered prostheses. In children, the main goal of introducing a prosthesis is to achieve age-appropriate milestones (Table 59–2). When there is normal cognitive ability, a child with LD will reach the appropriate milestones at the normative times; any deviations must be investigated.

Initial fitting and prescription are agreed on by the entire family-centered team: physician, prosthetist, occupational therapist, patient, and family. In school-age children, school performance is critical, and understanding those expectations is key. Historically, a prosthesis is introduced around 6 months of age; this is the age at which the child would be achieving sitting balance. However, children are now considered as early as 3 month of age. Age at introduction is guided by clinical experience. Early prosthetic fitting is designed to encourage bimanual tasks, establish a wearing pattern, provide for symmetrical crawling, and reduce “stump dependence”—sensory dependence on the end of the residual limb.^89,90 The prosthesis must fit comfortably, be relatively easily donned, equalize length with the noninvolved limb, allow for growth, and provide restoration acceptable to the family.⁷⁰ When introducing a prosthetic device, it is helpful to have models at hand to present to the parents and patients during the clinical evaluation. Introduction of a prosthesis is guided by clinical experience rather than by evidence-based medicine.⁹¹