Fibular hemimelia

Last revised by Frank Gaillard on 16 Mar 2024

Fibular hemimelia is a congenital lower limb anomaly characterized by partial or complete absence of the 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 5.7-20 cases per 1 million births 3. This condition is twice as common in boys as in girls.

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.

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, such as defects in the apical ectoderm ridge or defects secondary to an absent anterior tibial artery 3. Amniotic bands may be a factor causing insult to the growing limb bud in utero resulting in this condition 4. There has been a case of congenital absence of femur and fibular hemimelia related to maternal hyperpyrexia 5.

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

  • absence of the fibula: needs to be seen on both frontal and lateral radiographs as the fibula may be masked by the tibia in one view

  • shortening of the femur

  • lateral ray malformations

  • unilateral short lower limb

  • non-visualization of two bones in the leg region

  • an associated short femur may be seen in cases of proximal femoral focal deficiency

  • talipes equinovalgus deformity of the affected foot

  • syndactyly involving lateral toes: usually the 4th and 5th toes

  • absence of the fibula

  • absence or malformations of the lateral ray

  • there may be syndactyly and polydactyly

  • a 3D study is required for the assessment of limb length discrepancies and planning of surgical management

  • demonstrates the same features as plain radiographs and CT

  • 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 such as Ilizarov's technique or amputation with a prosthesis. Residual deformity and disability is common.

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