Congenital Coxa Vara

Congenital coxa vara is a developmental abnormality characterized by a primary cartilaginous defect in the femoral neck with an abnormal decrease in the femoral neck-shaft angle, shortening of the femoral neck, relative overgrowth of the greater trochanter, and shortening of the affected lower limb. Typically, the deformity either is not present at birth or is sufficiently subtle not to be recognized at that time. ^, Affected patients almost invariably present after walking age, and sometimes as late as adolescence, with a limp (Trendelenburg or short-leg gait) and, in unilateral cases, relatively mild limb length inequality.

This disorder has specific radiographic characteristics and a unique clinical presentation and should be distinguished from acquired causes of coxa vara deformity and coxa vara associated with congenital femoral deficiency. ^a

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In the literature, however, confusion and controversy exist regarding the terminology and classification of this disorder. Coxa vara has been variously referred to as “congenital,” “developmental,” “cervical,” and “infantile.” ^b

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To add to the confusion, some authors, in discussing developmental or congenital coxa vara, do not distinguish between the disorder described in this chapter and congenital coxa vara with short femur ^c

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; others include acquired causes of coxa vara. Furthermore, some cases of coxa vara are associated with skeletal dysplasias, especially cleidocranial dysostosis, metaphyseal dysostosis, and some types of spondylometaphyseal dysplasia. ^d

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Some authors exclude, and others include, this skeletal dysplasia–associated type of coxa vara in series describing developmental coxa vara. We believe that the term developmental coxa vara should be used to describe the clinical entity characterized by postnatal presentation of coxa vara without other known cause, with typically mild limb shortening and characteristic radiographic features; the deformity may or may not be associated with a generalized skeletal dysplasia. Acquired forms of coxa vara and those associated with significant femoral deficiency should be considered separate entities ( Box 16.1 ).

In 1881, Fiorani was the first to publish a clinical description of a case of bending of the neck of the femur. The term coxa vara was coined by Hofmeister in 1894. The association of coxa vara with other malformations was noted by Kredel in 1896. Amstutz, in 1970, described two patients with coxa vara who had previously had negative findings on radiographs of the hips. The term developmental coxa vara was first used by Hoffa in 1905 and later by Duncan. As mentioned previously, subsequent authors have used not only “developmental” but “congenital,” “infantile,” or “cervical” coxa vara to describe this condition.