primary defect in endochondral ossification of the medial part of the femoral neck.
Other theories regarding aetiology:
• Excessive intrauterine pressure on the developing fetal hip
• Vascular insult
• Faulty maturation of the cartilage and metaphyseal bone of the femoral neck
Bilateral in 30% to 50% of patients
• Present after they have started walking, but before 6 years of age.
• Painless limp due to a mild abductor weakness and mild limb length discrepancy
• If bilateral, the child presents with a waddling gait and increased lumbar lordosis
• The greater trochanter will be more prominent and proximal
• decreased ROM with maximum restriction in abduction and internal rotation.
• Decreased femoral neck-shaft angle
• Vertical position of physeal plate
• Triangular metaphyseal fragment in inferior femoral neck with associated inverted Y appearance, which is pathognomonic.
• Shortened femoral neck
• Decrease in normal anteversion
Hilgenriener’s epiphyseal angle (H-E angle): Angle subtended by the horizontal line connecting the tri-radiate cartilage and the physeal line. Normal angle: <30°
• HE Angle 45-60°: Observation and periodic follow up
• Indications for surgery: HE angle> 60°, progressive deformity, femoral neck shaft angle< 90°, development of trendelenburg gait
• Subtrochanteric valgus osteotomy. Adequate internal rotation of the distal fragment should be done to restore the femoral anteversion.
– Intertrochanteric osteotomy (Langenskold’s and Pauwel’s) is an alternative
– If the H-E angle is reduced to less than 38 degrees, 95% of the patients showed no evidence of recurrence
– Blade plate or a sliding hip screw is often used.
– An adductor tenotomy is frequently done.
– Spica cast immobilization is used, in addition, for 6 to 8 weeks in most patients.
Premature physeal closure may occur in the first 1-2 years after surgery.
This can cause recurrence of the deformity
Trochanteric apophysiodesis or a trochanteric advancement is done to prevent recurrence once physeal closure is documented.
In case of recurrence of varus deformity a repeat valgus osteotomy is done