Postaxial longitudinal defect


Longitudinal defects are defined as the absence or hypoplasia of a bone parallel to the long axis of the limb. The most common longitudinal lower-limb deficiency is hypoplasia of the fibula. About two thirds of cases are associated with other congenital disorders.

Postaxial defects occur on the lateral side of a limb. At superior limbs affecting: ulna, ulna and fifth digit, third through fifth digits, or the individual fourth and fifth digits; And in the lower limbs affecting: fibula with or without absence of the fifth and fourth toes. 

Postaxial longitudinal defects have a large spectrum of abnormalities, and two thirds have unilateral involvement, with the right side being more frequently affected.

On this presentation of postaxial longitudinal defect, there is no sign of fibular hypoplasia, as both distal fibulas are normal.

Complementation with bilateral lower limbs radiograph should be performed to ensure previous statement.

Anothers unusual aspect, not linked with longitudinal postaxial defects, is that midfoot and hindfoot bones are fused.