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Anterior superior iliac spine avulsion fracture in Adult
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Anterior superior iliac spine avulsion fracture in Adult

Contributors: Matthew F. Barra MD, Katie Rizzone MD, MPH, Surya Mundluru MD
Other Resources UpToDate PubMed

Synopsis

Causes / typical injury mechanism: Avulsion fractures from the anterior superior iliac spine (ASIS) are rare injuries seen almost exclusively in the adolescent population (aged 8-17 years).

Classic history and presentation: ASIS avulsion fractures present as pain, swelling, and weakness in the anterolateral hip at 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 ASIS avulsion in the general population is unknown, but it is estimated to account for 1.4% of all injuries to the hip and pelvis. It is the second most common avulsion fracture (22%) in the pelvis, behind ischial tuberosity avulsions (54%).
  • Age – Most commonly seen in patients aged 8-17 years.
  • Sex / gender – Males are more commonly affected than females.
Risk factors: Risk factors include an open apophysis and participation in running / sprinting sports (eg, soccer, track and field) and sports involving sudden muscular contractions (eg, gymnastics, baseball, hockey, tennis).

Pathophysiology: In the adolescent, 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 and tendinous attachments and are inherently weak until they completely fuse. Both the sartorius and the tensor fasciae latae (TFL) originate from the ASIS. The pathophysiology of ASIS avulsion is indirect trauma due to sudden and forceful eccentric contraction of the sartorius and TFL during hip extension, as can be seen during sprinting, jumping, or swinging a baseball bat.

Related topic: anterior inferior iliac spine avulsion fracture (AIIS)

Codes

ICD10CM:
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

SNOMEDCT:
428723000 – Closed avulsion fracture of anterior superior iliac spine of pelvis

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Muscle strain
  • Tendonitis
  • ASIS apophysitis – look for inflammation, normal imaging
  • ASIS traction apophysitis – from repetitive microtrauma; this may be chronic
  • Bone tumor
  • Myositis ossificans – history of trauma
  • Stress fracture of the pelvis

Best Tests

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Management Pearls

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Therapy

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References

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Last Reviewed:10/27/2021
Last Updated:01/10/2022
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Anterior superior iliac spine avulsion fracture in Adult
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