Anterior inferior iliac spine avulsion fracture in Adult
Classic history and presentation: The condition presents as pain, swelling, and weakness in the anterolateral hip a few centimeters distal to the groin line. Patients may have an antalgic gait secondary to pain. They may describe a pop or snap at the time of injury. Diagnosis is often based on history and physical examination in conjunction with radiographs.
Prevalence: The exact incidence of AIIS avulsion in the general population is unknown, but it is believed to be the third most common avulsion fracture (19%) in the pelvis behind ischial tuberosity (54%) and anterior superior iliac spine (ASIS) avulsions (22%).
- Age – Most commonly seen in patients 8-17 years of age.
- Sex / gender – Male predominance.
Pathophysiology: In the pediatric and adolescent child, apophyses are centers of bony growth that contribute to the overall contour of bone but do not contribute to longitudinal growth. They also serve as muscular or tendinous attachments sites. The direct head of the rectus femoris (RF) originates from the AIIS. The pathophysiology of AIIS avulsion is indirect trauma due to sudden and forceful eccentric contraction of the RF during hip extension and knee flexion, as can be seen during kicking and sprinting.
S32.313A – Displaced avulsion fracture of unspecified ilium, initial encounter for closed fracture
S32.316A – Nondisplaced avulsion fracture of unspecified ilium, initial encounter for closed fracture
426679004 – Closed avulsion fracture of anterior inferior iliac spine of pelvis
- Muscle strain
- AIIS apophysitis – look for inflammation, normal imaging
- AIIS traction apophysitis – from repetitive microtrauma; this is often chronic
- Bone tumor
- Os acetabuli
- Myositis ossificans (history of direct trauma)