Details of a 27-year-old lady with idiopathic ONFH: panel a: preoperative radiograph showing cam deformity at femoral head–neck junction; panel b: she presented with painful restriction of flexion and internal rotation; panel c: intraoperative picture showing a large cam deformity. Femoral head cartilage looks normal; panel d: intraoperative image after femoral of cam deformity; panels e and f: follow-up pictures showing near normal hip range of motion. Floor-level activities such as squatting and sitting cross-legged are restored; panels g and h: post-operative radiograph showing normal appearing joint after removal of cam deformity.