Serial anteroposterior and lateral left hip radiographs reveal aspherical left femoral head and an eroded acetabular articular surface with severe joint space narrowing, subchondral sclerosis and cysts, and underlying acetabular dysplasia and postosteotomy deformity. The images, in order from left to right, were taken when the patient was 23 years old (a), 25 years old (b), and 26 years old (c; 9 months after cyst curretage and grafting). The pertrochanteric cyst appeared to show graft incorporation and osseous remodeling of her proximal femoral metaphysis.