10 year-old female patient attends to the pediatric consultation complaining about pain in the anterior region of the right thigh to move it. She reports sudden onset of the symptom combined with claudication 5 months ago. Physical examination: weight: 61kg (z-score: > +3); height: 1,58m (z-score: > +3); severe loss of internal rotation of the flexed hip. It was requested a frog-leg radiography of the pelvis.