Coxa vara describes a hip deformity where the femoral neck-shaft angle is decreased, usually defined as <120°.
Pathology
It can be congenital or acquired. The common mechanism in congenital cases is a failure of the medial growth of the physeal plate 3.
Etiology
The etiology of coxa vara was originally classified by Fairbanks in 1928, modified by Finby et al. in 1956 1:
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idiopathic
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congenital
mild or severe coxa vara
often associated with other congenital anomalies (see Associations)
developmental: progressive, usually appearing between 2 and 6 years old
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rachitic: usually associated with active rickets
adolescent: secondary to slipped upper femoral epiphysis
traumatic: secondary to neck of femur fracture (which are rare in children)
inflammatory: secondary to tuberculosis or other infection
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secondary to other underlying bone diseases
capital coxa vara: occasionally seen in severe osteoarthritis and Legg-Perthes' disease
Associations
faulty development of the femur
camptodactyly arthropathy coxa vara pericarditis (CACP) syndrome 2