Consistent arterial abnormalities associated with a variety of congenital malformations of the human lower limb.

: A number of seemingly unrelated congenital deformities of the lower limb have been presented which include clubfoot, fibular deficiency, tibial aplasia, and diplopodia. Although the bony morphology in these limbs is quite different, they all share a strikingly similar arterial pattern, that being deficiency or absence of the anterior tibial artery, and of its derivative, the dorsal pedis artery. Since all of these diverse conditions share a similar aberrant arterial pattern, we suspect that the arterial changes are important in the pathogenesis of those conditions. Study of the soft tissue anatomy of these specimens suggests that the etiologic teratogenic event occurred early in embryonic development. In those limbs that contain the remnant of a missing structure, it is concluded that injury occurred after the mesenchyme was instructed to form that structure. These are termed "post-specification" defects. In those circumstances where limb duplication occurs, the injury affected the signal before instruction of mesenchyme to develop into a specific structure was completed and these abnormalities are termed "pre-specification" malformations. The musculotendenous and neurologic abnormalities seem to be reactive to the pre-existing bony pattern.