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What is a Femoroacetabular Impingement Syndrome (FAI)?

The hip joint is made of the femur and the pelvis. When the neck of the femur (top of the thigh bone) contacts the rim of the acetabulum (hip socket), a pinching or impingement occurs. This is termed femoroacetabular impingement (FAI). When this happens frequently as a result of sports or activities that put the hip into extreme flexion, adduction (towards the body), and internal rotation, there can be a buildup of bone on the neck of the femur (CAM lesion) or the rim of the acetabulum (pincer lesion). A detailed history as well as a clinical exam are key in the diagnosis of FAI. X-rays are commonly used to look for associated or predisposing factors. MRI arthrogram (dye injection) can be used to help confirm the diagnosis.


  • Hyperflexion or hyperextension of the hip with activity
  • Overuse of the hip in a flexed, adducted (toward the midline of the body), and internally rotated position
  • Increased laxity to the hip joint or other joints in the body
  • Extended period of activity at the extreme end ranges of hip motion

Signs & Symptoms

  • Deep aching hip pain during or after  activity
  • Possible painful clicking with hip flexion and rotation
  • Occasional sharp pains with activity
  • Possible decreased range of motion with the hip flexed, adducted, and internally rotated


Initial treatment of FAI is rest from all aggravating activities along with physical therapy to regain motion and strength. Strengthening of the core, hip rotators, glutes, and lower extremity are key. Sometimes joint mobilizations are used in order to provide a stretch to the capsule that may be causing pain or creating abnormal motion. If pain continues or worsens after following the non-surgical course of PT, surgery may be warranted to re-contour the neck of the femur or the rim of the acetabulum. If FAI goes undiagnosed or persists with conservative management, it is possible for FAI to create a labral tear in the hip due to constant compression of the labrum with the abnormal contour of the CAM or pincer lesion.

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