History and Physical Examination
Patients who have congenital coxa vara (CCV) usually present with gait abnormalities. Affected children generally present between the time they begin ambulation and age 6 years.
In most patients, the gait abnormality is progressive and, notably, pain-free. Unilateral involvement with an associated relative limb-length discrepancy and Trendelenburg limp may be noted. This discrepancy in limb lengths usually is mild, ranging from 1.5 to 4.0 cm. Patients with bilateral involvement commonly present with a waddling gait abnormality, similar to that of patients with bilateral developmental dysplasia of the hip (DDH). The Trendelenburg sign is commonly elicited in the affected hip or hips.
A tabletop examination may reveal weak abductors, a prominent greater trochanter, decreased abduction due to a decreased articulotrochanteric distance, and coxa vara. A decrease in internal rotation also is often noted, caused by decreased femoral anteversion or true retroversion associated with this condition.
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Congenital coxa vara (CCV). Hip biomechanics in coxa vara. (A, B) Normal hip. (C) Abnormal varus hip. Biomechanically, shear effect causing progressive varus deformity is best understood in relation to resultant force (R) at femoral-acetabular articulation. In normal hip, this resultant force would be perpendicular and compressive (C) in nature with respect to physis. Force transmitted to proximal femoral neck would include net tension force (T) at superior or lateral cortex and net compressive force (C) at inferior or medial cortex. In CCV, more vertical position of proximal femoral physis would increase not only shear component (S) of hip articulation resultant force but also net medial compressive force (C) on metaphyseal bone of femoral neck. These forces overwhelm mechanical strength of abnormally ossified bone in this area. This may lead to relentless and progressive cycle of deformity that often continues unless these forces are corrected with surgical intervention.
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Characteristic radiographic findings of congenital coxa vara. (A) Decreased neck shaft angle. (B) Smaller and flatter femoral head. (C) More vertical orientation of physeal plate. (D) Coxa brevis. (E) Abnormal bony fragment inferolateral to physeal plate and contained in inverted Y-shaped lucency.
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Congenital coxa vara. Determination of Hilgenreiner epiphyseal angle, using Hilgenreiner line as horizontal axis and line through defect adjacent to metaphysis as diagonal axis.
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Congenital coxa vara. Natural history of untreated progressive developmental coxa vara with premature degeneration of hip joint.
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Congenital coxa vara. Surgical methods of valgus-producing proximal femoral osteotomies. (A) Pauwels Y-shaped osteotomy. (B) Langenskiöld intertrochanteric osteotomy. (C) Borden subtrochanteric osteotomy.
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Surgical treatment of congenital coxa vara. Progression from preoperative radiographs at ages 2 and 5 years, with characteristic bony changes. Postoperative radiographs at ages 6 and 12 years, with early and late follow-up results.
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Greater trochanteric overgrowth in treated congenital coxa vara.
