Updated: 6/14/2021

Congenital Popliteal Webbing

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  • summary
    • Congenital Popliteal Webbing, also known as popliteal pterygium syndrome, is an inherited condition that affects the face, limbs, and genitalia. 
    • Diagnosis is made clinically by the presence of a characteristic web running behind the knee from ischial tuberosity down to the heel. MRI studies are helpful for operative planning to identify location of neurovascular structures. 
    • Treatment is generally surgical resection in the majority of cases. 
  • Epidemiology
    • Incidence
      • rare
        • affects 1:300,000
    • Demographics
      • affects males and females equally
  • Etiology
    • Genetics
      • inheritance pattern
        • autosomal dominant
        • can also be sporadic
          • associated with advanced paternal age
      • mutations
        • results from a mutation in the IRF6 gene
        • encodes a transcription factor that is active in cells that give rise to tissues in the head and face
          • also involved in the development of the skin and genitalia
    • Associated conditions
      • cleft lip/palate
      • syndactyly
      • criptorchidism
      • bifid scrotum
      • hypoplasia of the labia majora
      • congnitive delays
      • spina bifida
  • Anatomy
    • Popliteal pterygium
      • subcutaneous fibrous band
        • lies superficially along the free edge of the pterygium
      • sciatic/peroneal nerve
        • lies deep to the fibrous band, usually halfway between the free edge and the apex
      • popliteal artery/vein
        • usually lies deep in the popliteal space
  • Presentation
    • Physical exam
      • extensive web running behind the knee from ischial tuberosity down to the heel
        • usually bilateral
        • limits lower extremity extension, abduction, and rotation
      • syndactyly
      • triangular folds of skin over the nails of the large toes
      • tissue connecting the upper and lower eyelids (ankyloblepharon) or jaws (syngnathia)
      • abnormal genitalia
        • hypoplastic labia majora in females
        • cryptorchidism or bifid scrotum in males
      • cleft lip/palate
  • Imaging
    • Radiographs
      • recommended views
        • AP
        • lateral
      • findings
        • knee flexion contracture
    • MRI
      • indications
        • operative planning
          • used to assess location of neurovascular structures given wide variation and risk for injury
  • Treatment
    • Nonoperative
      • observation
        • indications
          • rare
    • Operative
      • surgical resection
        • indications
          • most cases
  • Techniques
    • Surgical resection
      • technique
        • resection or tenotomy of fibrous band
        • z-plasty of overlying skin
        • can perform sciatic nerve grafting or tendon lengthening if needed
Questions (1)

(SAE07PE.94) Figures 43a and 43b show the clinical photographs of a 4-month-old child with bilateral popliteal pterygium. The fixed knee contractures measure 100 degrees bilaterally. What future treatment is most likely to successfully correct this deformity?

QID: 6154
FIGURES:
1

Serial casting of both knees weekly

13%

(30/239)

2

Physiotherapy and dynamic splinting

7%

(16/239)

3

Soft-tissue releases of the knees, including Z-plasties of skin, excision of fibrotic bands, hamstring lengthenings, and posterior knee capsulotomies

48%

(115/239)

4

Femoral shortening osteotomies combined with soft-tissue releases of the knees (Z-plasties of skin, excision of fibrotic bands, hamstring lengthenings, and posterior knee capsulotomies)

29%

(69/239)

5

Gradual correction with a circular external fixator without soft-tissue release

2%

(4/239)

N/A E

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