Avulsion Fracture of the Anterior Superior Iliac Spine

What is Avulsion Fracture of the Anterior Superior Iliac Spine

Avulsion fracture of the anterior superior iliac spine (ASIS) is an injury to the bony part of the pelvis where a thigh muscle (sartorius) attaches to a tendon.

This muscle is important in bending the hip and straightening the knee. An avulsion fracture of the ASIS commonly occurs at a growth plate on the hip bone before the growth plate has closed (fused).

What are the causes?

This injury happens when a tendon pulls off a piece of bone during a powerful contraction of the sartorius. It often happens during activities that involve jumping or running, such as basketball, dance, track, and volleyball.

What increases the risk?

This injury is more likely to occur in:

  • People who play sports that involve running or jumping.
  • People who have poor strength and flexibility.
  • People who do not warm up properly before practice or play.
  • People who have had a previous injury to the hip, thigh, or pelvis.
  • People who are overweight.

What are the signs or symptoms?

Symptoms of this injury include:

  • Tenderness in the front of the injured hip.
  • Mild swelling, warmth, or redness over the injury.
  • Weakness with activity, especially when flexing the hip.
  • Pain with walking.
  • Pain with stretching the hip.
  • A popping sound that happens at the time of injury.
  • Bruising on the thigh within 1–2 days of the injury.

How is this diagnosed?

This injury is usually diagnosed with a physical exam and X-rays.

How is this treated?

This injury may be treated by:

  • Resting the injured area in a position that decreases the stretch on the involved tendon.
  • Walking with crutches.
  • Taking medicines for pain.
  • Working with a physical therapist to regain strength and motion in the injured area.
  • Surgery. This may be needed in severe cases in which the bone does not heal on its own.

Follow these instructions at home:

Managing pain, stiffness, and swelling

  • If directed, apply ice to the injured area:
    • Put ice in a plastic bag.
    • Place a towel between your skin and the bag.
    • Leave the ice on for 20 minutes, 2–3 times per day.


  • Do notdrive or operate heavy machinery while taking prescription pain medicine.


  • Return to your normal activities as told by your health care provider. Ask your health care provider what activities are safe for you.
  • Perform exercises daily as told by your health care provider or physical therapist.


  • Do notuse the injured limb to support your body weight until your health care provider says that you can. Use crutches as told by your health care provider.

General instructions

  • Do notuse any tobacco products, including cigarettes, chewing tobacco, or e-cigarettes. Tobacco can delay bone healing. If you need help quitting, ask your health care provider.
  • Take over-the-counter and prescription medicines only as told by your health care provider.
  • Keep all follow-up visits as told by your health care provider. This is important.

Contact a health care provider if:

  • Your symptoms do not improve.
  • You have tingling or numbness in the thigh or leg on the side of your injury.

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