Fibular hemimelia

Fibular hemimelia is a congenital lower limb anomaly characterised by partial or complete absence of fibula and includes a spectrum ranging from mild fibular hypoplasia to complete fibular aplasia 1.

Although rare in occurrence, it is the most common congenital absence of long bone of the extremities 2. The incidence has been suggested to be approximately 5.7 to 20 cases per 1 million births 3. This condition is twice as common in boys than in girls.

Fibular hemimelia is usually obvious at birth with limb shortening and limb-length discrepancy 2. Syndactyly, oligodactyly or polydactyly may also be present 4. It may also be detected antenatally during obstetric ultrasound evaluation for fetal anomalies 3.

Several theories have been put forward to explain this condition like defects in the apical ectoderm ridge, defects secondary to an absent anterior tibial artery 3. Amniotic bands may be one of the causal factors to insult to the growing limb bud in utero resulting in this condition 4. Kumar D and Krishnamoorthy S et al reported a case of congenital absence of femur and fibular hemimelia related with maternal hyperpyrexia 5.

Associations

Fibular hemimelia is usually an isolated anomaly and occurs sporadically. However, it can be associated with proximal focal femoral deficiency, absence of lateral rays and phalanges of lateral toes 1, syndactyly and polydactyly 4.

Classification

One of the commonly used classifications for fibular hemimelia is that of Achterman and Kalamachi et al 3, which divides the condition into two types:

  • type I: minimal hypoplasia of the fibula
  • type II: complete absence of the fibula
Fetal sonography
  • unilateral short for date lower limb
  • non visualisation of two bones in leg region
  • associated short femur may be seen in cases of proximal femoral focal deficiency
  • talipes equinovalgus deformity of affected foot
  • syndactyly involving lateral toes mainly the fourth and fifth toes
Plain radiograph
  • absence of the fibula, needs to be seen in both frontal and lateral radiographs as fibula; may be masked by the tibia in one view
  • shortening of the femur
  • lateral ray malformations
CT
  • absence of the fibula
  • absence or malformations of the lateral ray
  • syndactyly and polydactyly as the case may be
  • 3D study is required for assessment of limb length discrepancies and planning of surgical management
MRI
  • same features as can be seen with plain radiographs and CT imaging
  • additional pseudoarthrosis of the femur may be assessed in cases of proximal femoral focal deficiency
  • assessment of muscle bulk and agenesis

The management is mainly surgical and includes limb-lengthening procedures like Ilizarov's technique or amputation with prosthesis. Residual deformity and disability is usual than not.


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Article Information

rID: 27389
Section: Pathology
Synonyms or Alternate Spellings:
  • Fibular hemimelias

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