Understanding Femoroacetabular Impingement: A Guide to Diagnosing and Managing Hip Impingement Syndrome

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  • Understanding Femoroacetabular Impingement: A Guide to Diagnosing and Managing Hip Impingement Syndrome

What is Hip Impingement?

The hip joint is formed by the acetabulum (part of the pelvic bone) and the head of the femur. It is a shallow joint to allows a wide range of leg motions. The joint is stabilised by ligaments, muscles, and also a piece of cartilage known as the labrum. The labrum deepens the acetabulum and greatly increases the stability of the joint. This prevents it from dislocating.

In some patients, this labrum is caught by the surrounding bones in the extremes of joint movement. This can cause pain and is termed femoral acetabular impingement (FAI).

What causes the Impingement in FAI?     

The exact cause is often not well understood. Some cases of FAI are congenital (born with), whilst the cause of others can be difficult to pinpoint. There are two types of FAI impingement,

  • Impingement between a small extra bump of bone (CAM) over the neck of femur and the hip is termed CAM impingement.
  • Impingement caused by excessive coverage of the femoral head is known as pincer type impingement.

Regardless of the type of impingement, if left alone the impingement may lead to tears in the labrum. Labral tears heal poorly, and if left alone can result in hip osteoarthritis (OA). Hip OA is an extremely debilitating condition, and patients often find themselves unable to walk properly. Patients with established hip OA will generally require total hip replacement surgery.

What are the symptoms of a labral tear and FAI?

For FAI, there may be no symptoms for the initial stages. However, patients may start to experience symptoms after developing a tear in the labrum. Such symptoms may include,

  • Pain over the front of the hip joint (groin pain). That occurs or worsens during activity, and may get worse as the condition deteriorates.n
  • Stiffness in the hip, which may prevent some activities. In severe cases, patients may find themselves unable to put on socks or sit cross-legged on the floor.
  • Painful “clicking” sensation in the hip joint

How is a labral tear and FAI diagnosed?

Your doctor will conduct a medical interview and perform focused medical examination on your hips. This may entail a short walk to assess for abnormal gait patterns, palpating around your hip joint to elicit pain, moving your hip joint to check its range of motion.

In particular, your doctor may attempt to recreate the pain of FAI by placing your hips in 2 positions, FABER (Flexion, Abduction, External Rotation) and FADDIR (Flexion, Adduction, Internal rotation).

Based on the findings from the interview and examination, you might be asked to undergo imaging tests. This typically entails plain radiographs of your pelvis and hip. In most cases, a MRI scan will also be offered to confirm the diagnosis of FAI.

If there is any diagnostic uncertainty about FAI being the cause of hip pain, your doctor may offer a diagnostic hip injection, where a small amount of steroid and local anaesthetic is injected into the hip joint. If pain relief occurs, the diagnosis of FAI is confirmed.

How can a labral tear and FAI be treated?

In most patients with FAI without a labral tear, the treatment is supportive and non-surgical. A range of modalities may be offered to you. This includes,

  • Rest and lifestyle modification, avoiding activities that cause pain and could potentially worsen the condition.
  • Medications such as non-steroidal anti-inflammatory drugs to manage the pain.
  • A course of curated hip physiotherapy designed to improve hip range of motion and function
  • Injections as detailed above to reduce hip pain

Patients who have already developed torn labrums generally will require surgical treatment, especially for large tears. This is usually conducted via hip arthroscopy. Hip arthroscopy is a minimally invasive technique where a camera is inserted into the hip joint via small incisions. Utilising the camera, and a separate instrument portal, diagnostic and therapeutic procedures can be carried out.

Specific to FAI and labral tears, the tears can be repaired, and the extra bone causing impingement can be removed as well. Small labral tears can also be excised utilising arthroscopic techniques. This operation can be performed as day surgery, and patients usually recover quickly due to the small incisions used.

Rehabilitation and Recovery

Regardless of the method used to treat FAI/labral tears, most patients will be asked to undergo a course of hip physiotherapy. This may last for up to 6 months. Patients will undergo hip range of motion exercises, and strengthening exercises for the muscles around the hip joint. They may also undergo gait and postural training.

Most patients with repaired labral tears will be able to return to sport 3 months after surgical repair of their labral injuries.

For assessment of your condition, please book an appointment with Dr Yong Ren.

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Sarah Taylor

Obstetrics & Gynaecology