Upper Limb

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.

Child with congenital transverse upper limb difference.

Child with congenital transverse upper limb difference with body-powered prosthetic.

(Prosthesis fabricated by SCOPe Orthotics and Prosthetics.)

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. Longitudinal deficiency of the humerus is often associated with anomalies in the radius and ulna with phocomelic digits.

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 .

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.

Other Limb Differences

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.