A Painful Victory: A Case of Avulsion Fracture of Anterior Superior Iliac Spine

Avulsion fractures of the anterior superior iliac spine (ASIS) are rare, occurring mostly among young teenagers during sports.  This is due to the weaker, immature apophyseal cartilage in adolescent, when forceful muscle contractions avulse the ASIS during athletic activity. A 15-year-old male presented to the Emergency Department (ED) complaining of right hip pain after a race during his school’s Sports Day.  As he crossed the finishing line and won, he felt a popping sensation over his right hip and fell to the ground in pain. On arrival to ED, he was lying supine with the pain score of 6/10. Intravenous Ketorolac was given for pain relief.  Physical examination revealed localised tenderness over the anterior right pelvic region, with no swelling or deformity over the right hip joint. There was no limb length discrepancy of the right leg compared to the left. Active movement of the right hip was restricted due to pain. Neurovascular examination was unremarkable.  Plain radiograph of the pelvis showed avulsion fracture of the right ASIS.  He was referred to the Orthopaedics team and was planned for conservative management of bed rest, analgesics, and non-weight bearing ambulation. He was discharged home and planned for review as outpatient at the Orthopaedic Clinic.  Subsequent review 2 months post injury revealed patient was well and ambulating pain-free.. The ASIS is susceptible to avulsion injury during running activity as the sartorius muscle pulls the ASIS anteroinferiorly during maximum flexion of hip and extension of the knee. Although avulsion fracture of the pelvic apophyses is rarely encountered, it should always be considered among athletic adolescents if the mechanism of injury is highly suggestive.