Slipped Capital Femoral Epiphysis: Developmental Coxa Vara

Abstract

Coxa vara is not a disease; it is a descriptive term referring to the deformed position of the head and neck of the femur in relation to the long axis of the shaft. In a strict structural sense, coxa vara today refers to deformity of the proximal femur in which the head-neck axis on an anteroposterior radiograph forms an angle with the long axis of the femoral shaft which is 110° or less (Fig. 3.1). In a more dynamic and all-inclusive sense, coxa vara can be said to exist when any developing deformity of the proximal femur repositions the femoral head-neck relationship into a more varus conformation than previously existed and that is occurring in a relatively rapid and pathologic fashion not compatible with the normal developmental diminution of the head-neck-shaft angle. In the childhood years, the normal head-neck-shaft angle passes from a value as high as 145° to the normal adult range of 120–130°. When defined this way, the term coxa vara includes the broad range of developmental and acquired disorders that predispose to that shape of the proximal femur.