The pelvic x-ray shows an avulsion fracture of anterior superior iliac spine (ASIS avulsion). Sartorius is attached to ASIS and sudden forceful contraction of sartorius in adolescents results in this injury.

Treatment is usually conservative with rest, analgesia and protected weight bearing and orthopedic follow up.

Further reading https://www.orthobullets.com/knee-and-sports/3091/anterior-superior-iliac-spine-asis-avulsion