Updated: 10/30/2016

Anterolateral Bowing & Congenital Pseudoarthrosis of Tibia

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https://upload.orthobullets.com/topic/4056/images/Clinical photo - courtesy Miller_moved.jpg
https://upload.orthobullets.com/topic/4056/images/tibial bowing xray - courtesy Miller_moved.png
https://upload.orthobullets.com/topic/4056/images/Congenital pseudo xray - courtesy Miller_moved.png
https://upload.orthobullets.com/topic/4056/images/indianjorthop_2012_46_6_616_104184_f3.jpg
https://upload.orthobullets.com/topic/4056/images/Free fibula graft - courtesy Miller_moved.png
Introduction
  • Three types of tibial bowing exist in children
    • anterolateral bowing (this topic)
    • posteromedial bowing (physiologic) 
    • anteromedial bowing (fibular hemimelia) 
  • Anterolateral bowing is a continuum of disease that can be divided into
    • anterolateral bowing of tibia 
    • congenital pseudarthrosis of tibia  
  • Associated conditions
    • neurofibromatosis type I 
      • is found in 50-55% of patients with anterolateral bowing
      • only 6-10% of patients with neurofibromatosis will have anterolateral tibial bowing
  • Definition
    • A congenital bowing of the tibial diaphysis (anterolateral apex), associated with diaphyseal pseudoarthrosis
    • Pseudoarthrosis in not congenital, but in fact develops post-natally due to fracture non-union
  • Epidemiology
    • Incidence
      • Extremely rare
      • 1:140,000-190,000
    • Risk Factors
      • Up to 55% associated with Neurofibromatosis Type 1
      • 15% associated with Fibrous Dysplasia
Classification
  • Numerous classification systems have been proposed (Boyd, Andersen, Crawford) however none guide management or are predictive of outcome
  • Two classification criteria have been proposed to guide treatment:
    • The presence or absence of fracture
    • The age at which fracture occurs
      • "Early onset" < 4 years old
      • "Late onset" > 4 years old
Presentation
  • Symptoms
    • majority present with bowing in the first year of life
  • Physical exam
    • deformity 
    • careful skin examination for cafe-au-lait spots and other signs of neurofibromatosis
Treatment
  • The lesion does not self-resolve, and once fracture occurs there is low likelihood of spontaneous resolution
  • Nonoperative
    • bracing in clamshell orthosis or patellar tendon bearing (PTB) orthosis
      • indications
        • Children of ambulatory age (weight bearing)
        • bowing without pseudarthrosis or fracture
          • spontaneous remodeling is not expected
      • goal is to prevent further bowing and fractures
      • osteotomy for bowing alone is contraindicated
      • technique
        • maintained until skeletal maturity
  • Operative
    • surgical fixation
      • indications
        • bowing with pseudarthrosis or fracture 
    • amputation 
      • indications
        • typically indicated after multiple failed surgical attempts at union
        • severe limb length discrepancy
        • dysfunctional angular deformity
        • Method- Syme or Boyd amputation
Techniques
  • Surgical fixation
    • goals
      • resection of pseudarthrosis to grossly normal bone
      • correction of alignment
      • bone grafting and stabilization of the remaining segments
      • intramedullary splinting of the bone is desired
    • techniques
      • intramedullary nailing with bone grafting 
        • Resect the pseudarthrosis
        • Tibial shortening
        • Fixation with intramedullary rod
        • Bone graft
      • free vascularized fibular graft (Farmer's Procedure)
        • contralateral fibula is used, ipsilateral is involved in pseudarthrosis
      • Ilizarov or circular frame fixation with lengthening or bone transport
  • Amputation
    • Ankle disarticulation (Boyd or Syme amputation) preferred over resection at pseudoarthrosis site
    • Persistent motion at pseudoarthrosis site managed by prosthetic socket
Complications
  • Recurrent fracture
    • seen in 50% or more of patients even after initial union
  • Valgus deformity

  • Limb length discrepancy at skeletal maturity (average 5cm)

  • No treatment is considered to produce results in a predictable and acceptable fashion
 

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(OBQ04.255) Anterolateral tibial bowing is associated with which of the following lower extremity conditions in children? Review Topic

QID: 1360
1

Calcaneovalgus foot deformity

6%

(138/2231)

2

Congenital pseudoarthrosis of the tibia

67%

(1492/2231)

3

Fibular hemimelia

15%

(337/2231)

4

Congenital talipes equinovarus

6%

(138/2231)

5

Congenital vertical talus

5%

(115/2231)

ML 2

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