This newborn patient has talipes equinovarus (clubfoot), a congenital anomaly in which one or both feet are excessively plantarflexed and swung inward.  Clubfoot is a deformation, a type of anomaly that occurs when abnormal mechanical forces impinge upon an otherwise normally developing fetal structure, leading to alterations in shape or position.  Risk factors include any condition that restricts fetal movement, such as breech presentation, uterine fibroids, or multiple gestation.

Although some deformations can improve once the extrinsic constraint is no longer present (ie, after birth), prolonged/severe mechanical forces in utero may cause significant, often permanent, structural changes.  In cases of clubfoot, mechanical forces may contribute to defects in the developing bones, muscles, or tendons, resulting in a rigid abnormality (not seen in this patient with normal range of motion).

(Choice B)  Disruption refers to arrested development or destruction of a structure that was previously developing normally; it is often triggered by interruption of the blood supply.  For example, amniotic bands, which are fibrous tissues that can encircle and constrict fetal limbs, may lead to amputation of a distal extremity.  This patient's abnormal limb positioning is more indicative of deformation due to extrinsic compression rather than a disruptive insult.

(Choice C)  Dysplasia describes an inherent defect in tissue development due to the abnormal organization of cells.  For example, achondroplasia is characterized by defective endochondral bone formation due to a genetic mutation resulting in skeletal anomalies.

(Choice D)  A malformation is due to a primary defect (eg, genetic, teratogenic) in embryonic development that prevents the proper development of a structure.  For example, spina bifida, a malformation of the spine and spinal cord, is caused by failure of neural tube closure (in contrast to clubfoot, in which limb development proceeds normally until late gestation)

(Choice E)  A sequence refers to a group of anomalies that represent a cascade effect from a single defect.  For instance, Potter sequence is characterized by flat facies, pulmonary hypoplasia, and limb deformities (eg, clubfoot) resulting from oligohydramnios due to a urinary tract anomaly.  However, this patient has isolated feet deformities.

Educational objective:
A deformation anomaly is caused by abnormal extrinsic forces on a developing fetus.  Talipes equinovarus (clubfoot) is an anomaly in which the foot is plantarflexed and pointed inward due to restricted in utero movement.