Coxa Vara

Modern Study Review (AI-Generated)

High-Yield Summary

Developmental coxa vara is a rare pediatric hip deformity characterized by a decreased femoral neck-shaft angle due to abnormal enchondral ossification in the medial femoral neck. This leads to a varus deformity, altered biomechanics, and progressive shear stress on the proximal femoral physis. Clinically, it presents as a painless limp with limited hip abduction and internal rotation, often detected between ages 2-3 years. Early diagnosis and surgical correction are critical to prevent progression and preserve hip function.

Key Diagnostic Findings

Anatomy

• Pathology: Abnormal fibrous or fibrocartilaginous tissue in the medial femoral neck causing biomechanical weakness.
• Effect: Collapse of the medial neck leads to varus angulation and verticalization of the proximal femoral physis.
• Associated Conditions: Can be isolated or associated with bone dysplasias (e.g., spondyloepiphyseal dysplasia, Morquio syndrome), avascular necrosis (Perthes disease), infection, malunion, or slipped capital femoral epiphysis.

Clinical Presentation

• Age of Onset: Typically presents at 2-3 years old.
• Symptoms: Painless, lurching limp.
• Physical Exam:
• Positive Trendelenburg sign.
• Limited hip abduction and internal rotation (due to increased femoral neck anteversion).
• Possible limb shortening proportional to deformity severity.
• Increased lumbar lordosis if bilateral.
• Uneven thigh creases if unilateral.

Imaging

• Radiographs:
• Decreased femoral neck-shaft angle (<120° typically).
• Medial femoral neck defect appears radiolucent, often described as an inverted “Y” shape.
• Hip positioned in neutral or slight internal rotation for accurate measurement.
• Hilgenreiner-Epiphyseal (HE) Angle:
• Angle between Hilgenreiner’s line and metaphyseal defect line.
• >60° predicts progressive deformity.
• 45-60° is equivocal, requiring close monitoring.

Classification Systems

• No widely used formal classification beyond the Hilgenreiner-Epiphyseal angle for prognosis and treatment guidance.
• Distinguish Developmental Coxa Vara from Congenital Coxa Vara (which lacks fibrocartilaginous defect and is often linked with proximal femoral focal deficiency).

Current Gold Standard Treatment

Non-operative

• Limited role due to progressive nature and mechanical disadvantage.
• Observation only for mild deformities with HE angle <45° and no functional impairment.
• Close radiographic follow-up essential for borderline cases (HE angle 45-60°).

Operative

• Indications:
• HE angle >60°.
• Progressive deformity or functional impairment (limp, Trendelenburg gait).
• Procedure: Intertrochanteric valgus-producing osteotomy with abduction and derotation components.
• Goal: Restore femoral neck-shaft angle and reorient physis to reduce shear stress.
• Timing: Ideally performed as soon as the child begins to ambulate to prevent progression.
• Fixation: Modern internal fixation techniques (e.g., pediatric locking plates or blade plates) allow stable correction and early mobilization.

Modern Complications & Outcomes

Complications

Outcomes

• Early surgical correction yields excellent functional outcomes with restoration of painless gait and improved hip biomechanics.
• Delay in treatment increases risk of deformity progression, limb shortening, and secondary osteoarthritis.
• Long-term prognosis is favorable if treated before physeal closure and deformity progression.

Classic Clinical Notes

Coxa Vara

Developmental Coxa Vara

• A rare disorder (1/20,000) in which the proximal femur develops in a varus fashion due to an abnormality of enchondral ossification in the medial aspect of the femoral neck. The cause is unknown. There is no racial or gender predilection, and the disorder may be unilateral or bilateral.

• The pathology is that of abnormal fibrous or fibrocartilaginous tissue in the medial part of the femoral neck. It is biomechanically inferior, and under the normal stresses of body weight this characteristically triangular area collapses and the neck “bends” into varus. The upper femoral physis then moves from a horizontal alignment to a more oblique/vertical attitude, subjecting it to more shear stress.

• The clinical presentation occurs as a painless lurching limp, and can manifest at age 2-3 years. Note: it is painless. There may be associated shortening of the femur, the degree of which depends on the severity of the varus deformity. Like DDH, the thigh creases may be uneven if it is unilateral. Trendelburg test is positive, and lumbar lordosis may be increased, especially if bilateral. Abduction is limited, and internal rotation is limited by increased anteversion of the neck. The limited internal rotation distinguishes this from DDH.

• Coxa vara can also occur with various bone dysplasia – spondyloepiphyseal dysplasia, Morquio’s disease. It can also be the result of AVN from Perthes or sepsis, or from malunion of a femoral neck fracture or from a slipped capital femoral epiphysis.

• Radiographically, the neck shaft angle is decreased, which can only be assessed with the hips in neutral or slight internal rotation. The medial femoral neck defect is radiolucent and appears as an inverted Y with the physis, which is tilted in a more vertical direction.

• The Hilgenreiner-epiphyseal angle is used to quantify the deformity. This is the angle between Hilgenreiner’s line (through the triradiate cartilage) and a line along the METAPHYSEAL side of the defect in the femoral neck. The HE angle is used to predict which deformities will get worse:
• 60°: coxa vara tends to get worse
• 45-60°: difficult to predict – need close follow-up.

• If the HE angle is greater than 60, treatment is an intertrochanteric abduction/derotation osteotomy, with the aim to bring the physis into a more horizontal position and reduce the abnormal shear stresses across it. It would appear that the surgery should be done as soon as the child begins to walk.

• Note: differs from congenital coxa vara, which does not have the abnormal fibrous/fibrocartilaginous tissue, and is often associated with PFFD.

Last Updated on January 25, 2026 by orthonet