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Division of Pediatric Rehabilitation Medicine, Department of Pediatrics, Rady Children’s Hospital San Diego, University of California San Diego, 3020 Children’s Way, MC 5096, San Diego, CA 92123, USA
Child Amputee Prosthetics Project, Shriners Hospital - Los Angeles, 3160 Geneva St., Los Angeles, CA 90020, USAPediatric Rehabilitation Division, Children's Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027, USA
Congenital limb differences are uncommon and often go undetected until birth.
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A thorough history, physical examination, or diagnostic workup should be done for children with congenital limb differences to rule out syndromes involving other organ systems or known associations.
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Acquired amputations most commonly occur from trauma.
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Complications, such as pain and terminal bony overgrowth can occur after amputation.
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A multidisciplinary approach to management is recommended, when available.
Nature of the problem
The Centers for Disease Control and Prevention estimate that each year 2250 babies are born with congenital upper and/or lower limb deficiencies or reductions each year in the United States. This is approximately 6 per 10,000 live births per year, in a ratio of 2:1 upper to lower extremity.
Precise numbers for other forms of congenital limb differences (ie, limb length discrepancies, neuromuscular pathology leading to differences in limb) and joint deformities (ie, contractures) are not known. Recent data suggest a relationship between paternal occupation and increased prevalence of birth defects, including limb deficiencies, in offspring of artists.
No racial predilection has been noted. Medications known to affect limb development include thalidomide, retinoic acid, and misoprostol. Teratogenic causes are often challenging to discern, as prenatal history may be complicated by maternal recall bias, and the timing of limb development is coincident when the mother may not know she is pregnant.
Limb deficiencies can also be caused by vascular disruption (eg, amniotic band syndrome), vascular malformations (eg, Poland syndrome), or genetic factors (spontaneous point mutation). Findings from experimental animal studies suggest that limb deficiency in amniotic band syndrome may be caused by a cascade of hypoxia, cell damage, hemorrhage, tissue loss, and reperfusion.
Acquired amputations most commonly occur from trauma or disease (ie, neoplasm or infection.) A retrospective study done in the United States determined that there were more than 110,000 children younger than 18 years that presented to emergency rooms with traumatic amputation injuries during a 12-year period. The average age was 6.18 years, patients were predominantly males (65.5%), and finger amputations comprised 91.6% of the amputations.
Despite prenatal screening ultrasound scans, congenital limb deficiencies may not be detected before birth. The International Organization for Standardization (ISO) names congenital limb deficiencies as follows: transverse (normal limb development to a particular level, with no skeletal elements distally) and longitudinal (absence or reduction of an element within the long axis).
Terminology used to differentiate acquired amputations in the upper limb includes shoulder disarticulation, transhumeral, elbow disarticulation, transradial, wrist disarticulation, and partial hand amputation. The different forms of lower limb amputations are translumbar, transpelvic, hip disarticulation, transfemoral, knee disarticulation, transtibial, ankle disarticulation, and partial foot amputation.
Limb development occurs between 4 and 8 weeks after fertilization. Most limb defects are thought to occur during weeks 4 and 6, during times of rapid tissue proliferation.
Limb development is considered with respect to its 3 axes of growth (proximal-distal, anterior-posterior/radio-ulnar, and dorsal-ventral.) Each axis is controlled by distinct, yet coordinated, molecular pathways, which include fibroblast growth factors, sonic hedgehog, and the Wingless-type signaling pathways. Each pathway is responsible for its own differentiation, yet they work in concert and have complex interactions with signaling, regulation, feedback loops, and maintenance of the other axes and embryogenesis. Errors in these pathways can indirectly affect the appropriate operation of other signaling centers, which may reflect the presence of other organ systems involved in some children with limb deficiencies.
Polydactyly is a congenital hand difference resulting in an extra digit. The extra digit may be preaxial (radially located) postaxial (ulnarly located) or centrally located. Most cases of preaxial polydactyly are sporadic and occur unilaterally. However, if the extra thumb has 3 phalanges, it may be linked to a systemic syndrome, such as Holt-Oram syndrome or Fanconi anemia. Postaxial polydactyly is often found in patients of African or African-American descent and can be inherited in an autosomal dominant pattern. If the postaxial digit is found in a Caucasian patient, there may be an underlying syndrome, such as chondroectodermal dysplasia or Ellis-van Creveld syndrome.
Syndactyly is a condition in which the digits fail to separate into individual appendages. Syndactyly can be simple, in which only the soft tissues are involved, or it can be complex, in which the bone or nail of the neighboring fingers is involved. It is typically an isolated finding; however, it may be associated with certain syndromes, such as Apert or Poland syndrome. Apert syndrome, or acrocephalosyndactyly, is characterized by complex syndactyly, craniosynostosis, hypertelorism, exophthalmos, and mild mental retardation.
Amniotic constriction band, constriction band syndrome, or amniotic band syndrome can result in clinical manifestations including congenital limb differences, joint deformities, defects of the abdomen or chest wall, or craniofacial defects. Limb differences from amniotic band syndrome include digit or limb amputations, constriction rings, or acrosyndactyly. Multiple limbs can be involved, with greater involvement of the upper limb, especially the distal aspects and central digits. Because of the constriction, lymphedema can occur.
Transverse deficiencies of the upper limb can occur at any level. Partial hand deficiencies may have ipsilateral shortening of the radius and ulna with underdeveloped vestigial digits, often called nubbins. The most common transverse deficiency of the forearm occurs in the upper third, and children often have ipsilateral shortening of the humerus (Figs. 1 and 2). In those with transverse deficiencies of the forearm, the proximal radius at the elbow can be unstable and may subluxate anteriorly during extension. In a child with a congenital elbow disarticulation or transhumeral deficiency, an active elbow joint does not exist; hence, the child lacks the ability to grasp objects in the cubital fold. As the deficiency becomes increasingly proximal, as with shoulder disarticulations, it becomes increasingly difficult to perform functional activities. If the child has bilateral upper limb deficiencies at the more proximal levels, the child can work with occupational therapists to perform activities of daily living with their feet.
Longitudinal deficiencies are not as common as transverse deficiencies. However, cases of radial longitudinal deficiencies have been associated with more complex medical syndromes. Radial longitudinal deficiency (RLD) is a congenital anomaly that presents with a deficiency along the radial side of the limb. It is 3 times as common as ulnar longitudinal deficiencies. It has varying degrees of involvement from thumb hypoplasia with an intact radius to the complete absence of the radius. It may occur bilaterally. Most cases of RDL result from spontaneous mutations; however, there are cases in which it may be autosomal recessive or dominant. Approximately one-third of RLD cases are associated with a syndrome that may involve the hematologic, cardiac, or renal systems. Radial longitudinal deficiency can be seen in thrombocytopenia-absent radius syndrome, VACTERL (vertebral defects, anal atresia, cardiac malformation, tracheoesophageal fistula, esophageal atresia, renal anomalies, and limb anomalies) syndrome, Holt-Oram syndrome (cardiac septal defects), or Fanconi anemia. In those with less severe forms of RLD, such as thumb hypoplasia, treatment options may include opponensplasty, ulnar collateral ligament reconstruction, or pollicization depending on the level of involvement. For those with more severe forms of RLD, such as hypoplasia or absence of the radius, the shortened forearm may have a wrist that is radially deviated because of lack of bony support. This can lead to poor finger flexion and extension as the finger flexors and extensors are at a mechanical disadvantage. Surgical options, along with stretching and splinting, aim to maintain wrist and digit motion while centralizing the wrist relative to the forearm. The ultimate goal is to have a functional upper limb with a stable wrist and a functional oppositional thumb for pinch and grasp.
Ulnar longitudinal deficiency is less common than RLD and often occurs in isolation and unilaterally. The entire limb can be hypoplastic and have abnormalities of the elbow and forearm. The hand and wrist are almost always affected. Up to 90% of patients may have missing digits.
As with RLD, the goal is to have a functional upper limb with an oppositional thumb and fingers.
Children with central upper limb deficiency, ectrodactyly, or cleft hand, sometimes referred to as lobster claw, have variable absence of the index, middle, and ring rays and central carpus. It can be inherited in an autosomal dominant pattern or occur spontaneously.
When seeing a child with an upper limb difference, a history, including prenatal exposures and birth/family/developmental history and a thorough physical examination should be performed. A diagnostic workup, especially in a child with a radial longitudinal deficiency, should include:
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Echocardiogram
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Renal ultrasound scan
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Blood cell count
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Peripheral blood smear
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Spine radiographs
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Chromosomal challenge test, if Fanconi anemia is suspected
Lower Limb
Congenital lower limb differences occur less frequently than in the upper limb. The Centers for Disease Control and Prevention estimates that there are approximately 2 per 10,000 live births each year in the United States affected with congenital lower limb deficiencies.
Of these, the most common deficiencies are longitudinal toe reductions, longitudinal femoral deficiencies (proximal focal femoral deficiency [PFFD]), longitudinal fibular deficiencies, and longitudinal tibial deficiencies, in decreasing order.
Lower limb congenital malformations may progress with growth, depending on the extent and number of bones and growth plates involved. For example, in children with longitudinal fibular deficiency, the lateral femoral growth plate is often affected, causing progressive genu valgum. Most lower limb deficiencies are not associated with other organ system defects. Some exceptions are listed in Table 1.
Table 1Lower limb deficiencies associated with other organ system defects
Deafness, ectrodactyly or polydactyly of the hands, craniofacial abnormalities
Femoral hypoplasia-unusual facies syndrome
Bilateral femoral deficiency, facial abnormalities including micrognathia and cleft palate, hypoplasia or synostosis of the upper extremity, vertebral abnormalities, congenital heart disease, and polydactyly
Roberts or SC phocomelia syndrome
Bilateral symmetric tetraphocomelia, thumb aplasia, syndactyly, elbow and knee flexion contractures, mental retardation, cleft lip/palate, micrognathia, hypotelorism, cryptorchidism, and cardiac defects
Sacral agenesis
Hemipelvectomy or hip disarticulation, and is often associated with neurogenic bowel and bladder
In those with congenital lower limb differences, a comprehensive history and physical examination should be performed, including:
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Prenatal exposures and birth history
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Family history
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Developmental history, including gross and fine motor milestones
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Full review of systems to rule out possible syndromes, in particular, cardiac, musculoskeletal, eyes/ears/nose/throat, neurologic, gastrointestinal, and genitourinary
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Skin examination for dimples, scars, verrucous hyperplasia, breakdown, or other abnormalities; lymphedema associated with amniotic banding
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Joint assessment to determine stability and weight-bearing potential. Measure active and passive joint range of motion. Specifically, hip or knee dislocation and ankle stability are very important factors in surgical planning. Voluntary movement of the joint is also helpful in determining the child’s ability to use it in combination with a prosthesis or orthosis in the future. If the child is able to cooperate, perform quantitative strength testing.
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Spine examination for scoliosis or overlying skin abnormalities
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Observation to determine if the child has sufficient seated/standing balance
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Assessment of achieved mobility (eg, commando, bear, or reciprocal crawling). Note if the child attempts to pull to stand on objects in the room. Observe ambulation, if present.
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Sensory testing, if able
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A full physical examination to rule out major organ abnormalities (such as cardiac defects)
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Labs/Imaging
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If syndromic findings present on examination, consider appropriate genetic testing or consultation.
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Radiographs of the involved limb with opposite side comparison can be helpful in determining outcomes and possible surgical planning. A scanogram can help determine total limb length discrepancy at maturity in the child that can stand in combination with bone age. Consider spine films if abnormalities are observed on examination. It is important to remember that in the newborn, radiographs are often not conclusive because of the lack of bony ossification.
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Formal gait analysis should be considered for abnormal gait patterns, difficulty with functional prosthetic fitting, or surgical planning, when available.
In addition to the transverse and longitudinal limb differences mentioned earlier, there are myriad musculoskeletal and neuromuscular conditions that affect the limbs—congenital radioulnar synostosis, talipes equinovarus (club foot), and leg length discrepancy, to name a few.
Arthrogryposis and arthrogryposis multiplex congenita are terms used to describe infants or children who have multiple congenital contractures. Arthrogryposis implies that the contractures affect multiple body areas (ie, more than just club feet.) There are more than 400 conditions described as having multiple congenital joint contractures. The most common type of arthrogryposis is amyoplasia. Amyoplasia is a condition in which the newborn lacks muscular development and growth with multiple joint contractures. In these cases, the skeletal muscle is replaced by dense fibrous tissue and fat. Arthrogryposis is associated with fetal akinesia (decreased fetal movement.) In addition to the multiple joint contractures, they may also have osteoporosis caused by decreased fetal limb movement. The condition is usually nonprogressive and may improve over time with physical therapy and splinting, but surgical intervention is often necessary.
In the pediatric population, acquired amputations most commonly occur from trauma and disease (ie, neoplasm, infections), with trauma being twice as common as disease. Traumatic amputations can result in permanent physical damage and disability and psychological trauma and affect future functionality or goals. Most traumatic amputations occur in men.
In a retrospective study done over a 12-year period in the United States, more than 91% of the traumatic amputations were finger amputations, especially in the age group 0 to 2 years, with doors being involved in most cases. Adolescent males experience a higher proportion of more serious amputation injuries.
Greater than 90% have single limb involvement. Of the more serious amputation injuries, 60% affect the lower limb. Lawn mower accidents, bicycle chains or spokes, tools, and motor vehicle collisions also contribute to pediatric amputations.
Aside from the physical, emotional, and psychological effects a traumatic amputation can have on a child and their family, the financial cost can also be a stressor. Acute care costs in train injuries resulting in amputation averaged more than $50,000 in one study, most of which involved the lower limb and usually required multiple debridements and revisions.
In another study, over a 10-year period, the average cost was $22,000, and most of these injuries were caused by power lawn mowers. Lawn mower injuries cause 11.1 injuries per 100,000 US children per year.
Of those, almost half are caused by the power lawn mower being operated in reverse. Prosthetic costs from time of injury to age 18 years can range from $73,000 to $116,000 per single lower limb amputation. With an average of 600 pediatric amputations every year from lawn mower injuries, the annual burden of cost ranges from $44 to $75 million.
Farm equipment is a common cause of traumatic amputation in rural areas. It is estimated that in the United States, 200 children per year have orthopedic injuries severe enough for hospitalization from farm equipment. Younger children are more likely to be injured from falling off equipment or being run over, whereas older children become injured while riding or operating it.
Education, safety, and prevention (ie, door stop being placed above child’s reach) can help prevent traumatic amputations.
Diseases and their complications can lead to amputations. Neoplasms are a frequent cause of disease-related limb amputations.
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Some tumor types that may result in amputation: osteogenic sarcoma, Ewing’s sarcoma, rhabdomyosarcoma
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Highest incidence: ages 12 to 21 years
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Limb salvage versus amputation depends on
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Aggressiveness of tumor
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Stage
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Responsiveness to neoadjunct therapy
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Likelihood of getting tumor-free margins
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Thanks to advances in treatment, survival rates have gone from 15% in the 1970s to 60%–70% with surgery and chemotherapy.
In the event of limb salvage procedures, if a child has an endoprosthesis, they cannot participate in any contact sports (usually met with variable compliance).
Several studies have shown equivalent survival rates and long-term outcomes of those having limb salvage procedures versus amputation, with the exception that children undergoing limb salvage have higher complication rates.
For intercalary injuries, including neoplasm, the Van Nes rotationplasty may offer superior results than high amputation. In this surgery, the distal limb (the part of the limb farthest away from the body's center) is attached to the proximal limb (the part of the limb closest to the body's center) with the foot facing backwards. The foot/ankle then acts like the knee joint and a prosthesis is attached to it. This allows the patient improved control of the prosthesis, including the ability to ascend or descend stairs and inclines.
Complications from infections can also lead to amputations. Purpura fulminans can be caused by meningococcal septicemia as well as staphylococcus and streptococcus infections. It is characterized by rapidly progressive hemorrhagic necrosis of the skin and thrombosis. Infectious emboli from meningococcal septicemia may cause autoamputation of the digits or limbs. In addition to the amputation, frequently in multiple limbs, growth plates may be affected leading to angular deformities of the limb during growth. Skin may also be affected, possibly requiring skin graphs and prolonged wound care management to maintain skin integrity.
The patient and physician may decide to fit one, some, or all amputated limbs with prostheses depending on the use, functional need, and preference.
Complications postamputation
After a major life event, such as an amputation, there needs to be physical, mental, emotional, and psychological healing.
Pain can occur immediately postoperatively, and phantom limb pain is unique to those with amputations. Phantom limb pain is a painful sensation perceived in the missing limb after an amputation. Phantom limb pain can occur in 40% to 85% of the adult population with amputations.
In a sample of 25 pediatric patients who underwent amputations caused by tumors, 19 of 25 (76%) had phantom limb pain within that first year postoperatively. However, by 1 year, only 2 had phantom pain (3 patients died during that year, and the other patient was discharged from the institution.) Treatment options may include oral medications (gabapentin, tricyclics), perioperative epidural analgesia, or peripheral nerve blocks.
Terminal bony overgrowth can occur in children with acquired amputations through a bone and in congenital limb deficiencies. The terminal overgrowth results from the development of appositional new bone on the end of the residual limb.
A multidisciplinary/interdisciplinary approach is recommended when available, with biannually coordinated assessments by the physician, physical therapist, occupational therapist, prosthetist, social worker, psychologist, and nurse. In addition to managing the medical complications, the physiatrist can assist with the patient’s life care plan to include potential changes in function/functional goals, medical concerns that may be encountered as the patient ages, planning for a prosthesis, adaptive equipment, therapies, psychological needs, and peer support.
The physical therapist can assist with contracture prevention, core strengthening, balance, gait, endurance, and work on a home exercise program. The occupational therapist can evaluate activities of daily living and assist with adaptive fitting, and, in the case of concomitant upper limb involvement, the patient may need to learn how to use his or her feet for activities and will need to remove the prosthesis for foot use. The prosthetist inspects the integrity of the prosthesis and makes adjustments for growth as necessary to ensure adequate fit in collaboration with the physician. A social worker and psychologist are often needed to assess the patient and family for psychosocial risk factors, depression, problems with self-image/self-esteem, acceptance of disability, and bullying or other school issues. Multidisciplinary management best ensures holistic care of a developing, growing child with a limb difference or acquired amputation. In the community-based practice in which a multidisciplinary approach is unavailable, physician follow-up should be coordinated with the prosthetist whenever possible. Fitting a prosthesis should be considered along with the age and developmental milestones of the child with a congenital limb difference.
In children with an upper limb difference or acquired amputation, a review of the last 25 years of English-language publications has found that prosthesis use rejection is 45% with body-powered prosthetics and 35% rejection rates with myoelectric prosthetics (these rates are much higher than those in the adult population of 26% and 23%, respectively.)
For those that choose to use a prosthetic arm, there are many options for terminal devices which the pediatric patient may want to use for task-specific skills (Fig. 3, Fig. 4, Fig. 5).
Fig. 3Terminal device for basketball.
(Courtesy of TRS Prosthetics, Boulder, CO; with permission.)
The ability to bear weight and ambulate should be evaluated as early as possible in the child with lower limb difference or acquired amputation, and all appropriate surgical or prosthetic options should be presented to the family. Sometimes surgery is needed to make the limb amenable to prosthetic fitting and improve function, or limb salvage/lengthening procedure may be appropriate. Often, this discussion can be postponed until the child has met the gross motor milestone of pulling to stand. Parents may opt to wait for any surgical intervention until the child is old enough to make the decision, often necessitating the physician and prosthetist to use creative solutions for functional prosthetic fitting around a limb deformity.
Initially, children may need a Silesian or waist belt for improved suspension, particularly if they are still transitioning from crawling or have bilateral limb deficiencies. Contrary to the adult amputee, intensive physical therapy for gait training is seldom needed, and gait aides often are only transitionally necessary and can sometimes be circumvented by the use of push-type toys in the young child.
For above-knee or knee-disarticulation amputees, the timing of the addition of a mechanical knee unit is still somewhat controversial. Usually, children are fit with a knee unit between ages 3 and 5 years, with concomitant physical therapy for gait training and safety. For bilateral lower limb involvement, fitting them with manual locking knees for comfort when sitting is often more appropriate because of risk of falls. These can be unlocked by the prosthetist one at a time for free-swinging use in gait when the child shows sufficient strength and balance.
The prosthesis should be reviewed by the prosthetist frequently and modified for growth, usually every 4 to 6 months. When growth velocity slows and limb volume is constant, adult-type of suspension systems may be introduced, such as suction or vacuum sockets.
Children often prefer to ambulate without their prosthesis at home, even after amputation. Home environment and equipment, such as arm crutches/walker and bath seat should be provided where appropriate.
Presence of knee or ankle function can drastically improve options for surgical conversion and prosthetic fitting. For example, in the case of PFFD, the presence of ankle range of motion/stability with lack of knee function may offer possibilities of Van Nes rotationplasty surgery. This option offers superior control and function over a mechanical prosthetic knee (Figs. 6 and 7).
In devising a prescription for a child, the patient and family goals, aim for functionality, and aesthetic concerns must be taken into account. When selecting a prosthesis, one may compromise function for aesthetics and vice versa. Therefore, the clinician must identify the child’s and family’s priorities.
In children with upper limb prosthetic needs, there are options or opportunities for adults that are not yet available to younger patients, such as targeted muscle reinnervation, prostheses with combined motions with multiple degrees of movement, or multiarticulated prosthetic hands.
In patients with lower limb amputations, activity levels have generally been classified by the Medicare Functional Classification Level, or K-level. K-level is defined as a subjective assessment of current activity level of the amputee based on self-report and clinical observation (Table 2).
Table 2K-levels
K0
Functional Level 0
The patient does not have the ability or potential to ambulate or transfer safely with or without assistance, and a prosthesis does not enhance quality of life or mobility.
K1
Functional Level 1
The patient has the ability or potential to use a prosthesis for transfer or ambulation on level surfaces at fixed cadence. (Limited and unlimited household ambulator.)
K2
Functional Level 2
The patient has the ability or potential for ambulation with the ability to traverse low-level environmental barriers, such as curbs, stairs, or uneven surfaces. (Limited community ambulator.)
K3
Functional Level 3
The patient has the ability or potential for ambulation with variable cadence. Community ambulator who has the ability to navigate most environmental barriers.
K4
Functional Level 4
The patient has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, or energy levels. (Child, active adult, or athlete.)
Children are often classified as K4 level. A proposed measurement of community-based gait performance in children is the quantified data collected by an ankle-worn accelerometer, worn over a particular time period.
However, this measurement has yet to be widely applied in pediatric amputees. Questionnaires such as the Prosthetic Profile of the Amputee and Prosthesis Evaluation Questionnaire have not yet been validated in the pediatric population. This remains an area in need of further research. Subjective measures of prosthetic use/fit can include extracurricular activity, pain assessments, and skin evaluation.
Congenital limb deficiencies are uncommon skeletal birth defects that may go undetected even with prenatal screening ultrasound scans. The most common etiology of acquired amputation is trauma. These children may have medical complications that prove challenging to manage. However, with a multidisciplinary/interdisciplinary team working with the child and family, the child can lead a successful, functional, and fulfilling life.
Resources
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Association of Children’s Prosthetic-Orthotic Clinics www.acpoc.org
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