The embryology of lower-extremity torsion.

The presence of torsional deformities in the lower extremities of otherwise normal children is based on a variety of developmental processes. With intrauterine maturation, both rotation and external compression of the extremities take place. These forces result in the normal molding and final position of the limbs. Torsion of the extremities is, thus, a normal embryological process. It is imperative for the treating physician to understand these factors in human development to decide which cases are significant deviations from normal torsion. Knowledge of the embryology and natural history of these conditions is a key to appropriate treatment of patients with torsional or angular malalignments.