Transverse Deficiency

TOPIC: Transverse Deficiency

Essential Information:
This anomaly is seen as a failure of formation of the terminal portions of the upper extremity, which can occur at any level from the fingers to the upper arm.
 
  • Etiology
    • thought to be due to an insult affecting the apical ectodermal ridge (AER) after limb bud formation
  • Genetics
    • sporadic, no familial incidence has been shown 
  • Incidence
    • rare, represents only 6% of congenital upper extremity anomalies
  • Risk Factors
    • usually seen in isolation, with no other associated factors
Clinical Evaluation:
  • History / Exam Findings
    • often identified as isolated finding on prenatal ultrasound screening
    • vast majority are unilateral
      • if more than one extremity involved, look for possible syndromic conditions
    • most common level of deficiency is at the proximal portion of the forearm
    • the terminal end is usually well padded
      • may have tiny residual digits (‘nubbins’)
    • can appear similar to constriction band syndrome, however:
      • distinction is that it is unusual for constriction band syndrome to involve a single extremity (i.e. there are additional ‘bands’ seen in other parts of the body)
  • Imaging / Lab Studies
    • plain radiographs are important to look for additional anomalies:
      • carpal fusions
      • abnormal bowing of the forearm
      • radioulnar synostosis
      • radial head dislocation
  • Classification Schemes
    • no specific classification system
    • described according to the level of the most distal (terminal) bone segment
Treatment:
  • Conservative
    • majority of children adapt well to the condition with varying (often mild) functional difficulties
      • below–elbow amputees do not show diminished quality of life issues (James, 2006)
  • prosthetic use
    • consider passive prosthesis at an early age to developbi-manual dexterity
    • change to adaptive, conventional or myoelectric types as child matures
  • Surgical
    • address skin issues at terminal end of extremity
    • contour terminal end for prosthesis fitting
    • treat bone over-growth
    • less common surgical interventions
      • limb lengthening
        • improve prosthesis fit/function
      • toe-to-hand microvascular transfers
        • rare, because mid-hand level amputation is uncommon
Outcomes: 
  • Prognosis
    • generally good, children adapt well to anomaly
    • ‘newer’ prostheses are become lighter in weight
      • 3-D printed prosthetic devices (http://enablingthefuture.org/upper-limb-prosthetics)
  • Potential Complications
    • prosthetics over life-time use
      • cost
      • current myoelectric types are heavy/bulky
      • durability issues
    • child may not use device, due to lack of sensory feedback
    • surgical complications
      • bone over-growth
      • skin breakdown over terminal end of extremity
Recommended Readings:
  • Kozin SH. Upper-extremity congenital anomalies. The Journal of Bone and Joint Surgery- American volume 2003; 85-A:1564-76
     
  • James MA, Bagley AM, Brasington K, Lutz C, McConnell S, Molitor F. Impact of prostheses on function and quality of life for children with unilateral congenital below-the-elbow deficiency. The Journal of Bone and Joint Surgery-American volume 2006; 88:2356-65
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