summary An anterior superior iliac spine (ASIS) avulsion is a traumatic avulsion of the ASIS due to a sudden and forceful contraction of the sartorius and tensor fascia lata that occurs in young athletes. Diagnosis is made radiographically with displaced injuries but CT/MRI may be required to diagnosis nondisplaced fractures. Treatment is nonoperative for fractures < 3 cm displacement with rest and protected weight bearing. Surgical treatment is indicated for fractures > 3 cm displaced. Etiology Mechanism result from indirect trauma caused by sudden and forceful contraction of sartorius and tensor fascia lata occurs during hip extension (sprinting or swinging a baseball bat) Anatomy Muscles that originate from ASIS sartorius (femoral n.) tensor fascia lata (superior gluteal n.) Presentation History athlete will often report a pop or snap at the time of injury Symptoms may complain of weakness may be confused or misdiagnosed as an acute muscle strain Physical exam may see weakness to hip flexion and knee extension severe injuries may result in a limp Imaging Radiographs displaced fractures usually can be seen on radiographs may be missed due to location and small size of bony fragment CT or MRI can be obtained to confirm the diagnosis Treatment Nonoperative rest, protected weight bearing with crutches, and early ROM and stretching indications most cases Operative ORIF of avulsion fracture indications fractures with displacement of > 3 cm painful nonunions