Femoro-acetabular Impingement (FAI)

The hip is a ball and socket joint that connects the thigh bone (femur) to the hip socket in the pelvis (acetabulum) to allow movement of the legs. The hip joint consists of the thigh bone and pelvis that are both covered in a smooth tissue called cartilage and separated by fluid to cushion the joint and allow smooth movement. The bones are held together by ligaments, tendons and muscles.

In a normal hip, the head of the femur moves smoothly within the hip socket enabling movement without pain. With femoro-acetabular impingement or FAI, the femur pinches against the cartilage in the hip socket impeding smooth movement and causing pain.

Femoro-acetabular impingement is a condition in which the femoral head does not perfectly fit into the acetabulum due to the bones of the hip joint growing abnormally. This causes the bones in the hip joint to rub against the other on movement resulting in damage to the joint.

Femoro-acetabular impingement can cause:

  • Hip arthritis
  • Labral tears – The labrum is a ring of fibrous cartilage that sits along the rim of the hip socket (acetabulum) to ensure the top of the thigh bone (femoral head) is head securely in the socket. Tears to the labrum can result in pain, locking or clicking of your hip joint, and reduced movement.
  • Cartilage damage

There are three types of femoro-acetabular impingement:

  • CAM impingement deformity – the femoral head is not perfectly round and cannot rotate smoothly in the hip joint. This causes the cartilage to be worn away in places, and the bones to rub against each other on movement.
  • Pincer – occurs when the acetabulum grows too far over the femoral head resulting damage to the labral cartilage.
  • Combined – occurs when a combination of CAM and Pincer types of femoro-acetabular impingement are present.
  • Pain is the most common symptom. Pain can appear:
    • In the groin
    • In the lower back
    • Over the hip joint
    • On movement such as squatting, twisting or turning
  • Stiffness
  • Reduced movement
  • Locking or clicking of the hip joint
  • Limping

This is a text block. Click the edit button to change this text.Femoro-acetabular impingement is the result of abnormal growth of the bones in the hip joint. People who are more active may experience symptoms earlier than less active people.

How is femoro-acetabular impingement diagnosed?

If you are experiencing ongoing pain or stiffness in or around your hip joint that affects your mobility, you should consult your doctor. Your doctor will assess your medical history of your pain and other symptoms and family medical history. A physical examination will also be performed to assess your range of hip movement. As part of the physical examination, your doctor will conduct an ‘impingement test’. Your doctor may also refer you for an x-ray of your hip joint and on occasions a MRI and/or CT scan is also required.

Non-surgical management

Initially, Femoro-acetabular impingement is generally managed with non-surgical options that include:

  • Rest
  • Avoidance of activities that cause symptoms
  • Physiotherapy
  • Anti-inflammatory medications
  • Pain medication
  • Injection of steroid and analgesic into the hip joint

Surgical treatment

Once symptoms cannot be managed effectively with non-surgical options, your doctor may recommend a hip arthroscopy to repair the damage to the joint. A hip arthroscopy is a minimally invasive surgical procedure in which a small fibre-optic camera (arthroscope) and special surgical instruments are inserted into the hip joint through small incisions. The camera is attached to a monitoring screen that allows your surgeon to view and access any damage within the hip joint and to perform repairs as necessary.

Further reading


The information held on this page is for educational purposes only.

Individual results may vary from patient to patient and not all patients are suitable for this treatment. Please consult your specialist prior to considering any medical intervention.

As with any surgery, knee replacement surgery has serious risks associated with it and these should be considered prior to deciding to proceed.

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