Congenital unilateral posteromedial bowing of the tibia and fibula: insights regarding pathogenesis from prenatal pathology. A case report

Congenital posteromedial bowing of the tibia and fibula, in which both bones are medially and posteriorly bowed at either the middle or distal third of the shaft, is an uncommon anomaly of unknown etiology and pathogenesis1-3. A calcaneovalgus alignment of the ipsilateral foot usually coexists1-6. Although the angular deformities spontaneously resolve with growth, residual shortening (3 to 7 cm) of the tibia and fibula is typically present by skeletal maturity1,3,5-8.The pathogenesis of congenital posteromedial bowing is poorly understood. To the best of our knowledge, no description of the morphological changes in the tibia and fibula has been reported in the literature. We report the pathological findings in the tibia and fibula of a fetus with congenital posteromedial bowing of the tibia and fibula, which was legally aborted during the twenty-fourth week of gestation. We propose a possible relationship between these findings and the etiology of this deformity.