Congenital coxa vara is a deformity of the hip caused by an osteochondrodysplasia of the femoral neck and usually characterized by distinctive roentgenographic changes. Because of its infrequent occurrence, this condition is often mistaken for a variety of other diseases, and proper treatment is needlessly delayed or withheld. Early corrective surgery is almost always followed by a good result; whereas other measures frequently lead to increasing deformity. The literature concerning congenital coxa vara was reviewed by Zadek in 1935 (13). Relatively few articles have appeared on the subject since that time, although there have been several reports in the last five years (2, 7, 9, 10, 11). Etiology The etiology of congenital coxa vara has never been definitely established. The deformity is the result of osteochondrodysplasia of the femoral neck. Cases have been reported in identical twins (2) and also in siblings (5). The occurrence of the process as a solitary lesion tends to exclude a generalized metabolic disorder, such as rickets, as an etiologic factor. Pathology Under normal conditions, the femoral neck develops as an upward and medial growth of the diaphysis. Fusion of the epiphysis occurs between seventeen and nineteen years of age. A diaphyseal spur grows medially under the femoral head, causing the epiphyseal plate to become horizontal, supporting the head from below. In congenital coxa vara the cartilage of this spur does not ossify normally, and a more vertical epiphyseal plate results (Fig. 1). A cartilaginous plate is often seen extending into the metaphysis, giving rise to the formation of a separate bone fragment (Fig. 4). This fragment of bone corresponds to the normal supporting ledge for the femoral capital epiphysis. Rather than actually originating from the metaphysis, it is possible that this fragment represents a separate ossification center. Occasionally an irregular mixture of bone fragments, cartilage, and fibrous tissue is found in the metaphysis beneath the deformed epiphyseal plate. The capital epiphysis is displaced downward in relation to the trochanters, but retains its normal shape. The shearing forces concomitant with weight-bearing act upon the deformed femoral neck to produce coxa vara. Barr (3) removed material from the midcervical region of the femur. Histologically, it showed abnormal enchondral ossification, islands of disintegrated cartilage, and some bone atrophy. “Nowhere was there marked evidence of bone formation, nor was there evidence of repair.”