Case that developed arthritic changes (non-dysplastic, positive crossover sign). Left: radiograph before the follow-up (age 34 years old, female); the patient underwent Chiari osteotomy on the contralateral side for developmental dysplasia. Middle: radiograph from 16 years after the beginning of the follow-up (age 50 years old); the joint space was slightly narrower, and a bone cyst was noted on the acetabular side. Right: radiograph after the end of the follow-up (age 51 years old); the patient complained of severe pain in the hip. Therefore, she underwent femoral subtrochanteric varus osteotomy and allogenic bone grafting into the bone cyst to prevent collapse.