At 18 months after bilateral varus derotation osteotomies (VDROs) with angled blade plate (ABP) fixation, the hips are well contained; some remodelling of both the femoral head and the acetabulae has occurred, and the lateral acetabular epiphysis has appeared on both sides. However, there was penetration of the calcar in the left hip with type 3 avascular necrosis (AVN) changes in the femoral head, the significance of which will not be apparent until long-term follow-up. Penetration of the calcar may be a risk factor for AVN.