Femoroacetabular impingement

Causes of femoroacetabular impingement

Femoroacetabular impingement is the result of deformity of the hip bones which occurs in childhood as the bones grow. It is not possible to prevent the condition although not everyone goes on to develops symptoms. It is believed that people who participate in high impact exercise may experience pain earlier than people who are more sedentary, but exercise is not the cause of femoroacetabular impingement.

There are three different types of femoroacetabular impingement:

• Pincer impingement is where a section of bone extends beyond the normal rim of the acetabulum, causing the labrum to get crushed against the rim.
• Cam impingement is where the femoral head is not properly rounded which means it cannot rotate properly within the acetabulum. Over time a bump develops on the edge of the femoral head which grinds away the cartilage inside the acetabulum leading to worsening pain.
• Combined impingement is when both pincer and cam impingement.

Symptoms of femoroacetabular impingement

Femoroacetabular impingement causes a dull aching sensation and stiffness in the groin and outside of the hip which worsens as the condition progresses. You may develop a limp when you walk and movements like turning or twisting can cause a sharp pain.

Diagnosis of femoroacetabular impingement

To diagnose femoroacetabular impingement, your doctor will ask you to make a series of movements such as bringing your knee up towards your chest and then rotating it. If femoroacetabular impingement is present, this will cause pain in your hip and groin. You will be referred for further tests to confirm the suspected diagnosis. A local anaesthetic may be injected into your hip joint. If it provides temporary relief from pain, this will confirm that you have femoroacetabular impingement. An X-ray can show any abnormality in the hip bones as well as early signs of arthritis and an MRI scan may be used to identify damage to the labrum and articular cartilage. A harmless dye may be injected into the joint during the scan to show up any damage more clearly. In some cases you may also be given a CT scan which provides a more detailed picture of the hip bones than a standard X-ray.

Treatment of femoroacetabular impingement

In the first instance, your doctor may recommend conservative treatment of femoroacetabular impingement to avoid the risks associated with more invasive treatments. It can be helpful to think about what you were doing when the pain first occurred. By avoiding this activity you may be able provide some respite in your symptoms. Taking painkillers and anti-inflammatories may help and a physiotherapist can recommend exercises to improve hip mobility and strengthen the muscles around the joint, which can relieve stress on the injured labrum or cartilage.

As the condition develops and the pain worsens, you may require surgery. Most cases of femoroacetabular impingement can be treated arthroscopically, which means using keyhole surgery. A small incision is made over the hip joint and the surgeon inserts a tiny camera called an arthroscope, which provides a detailed view inside the hip. Using ultra fine surgical instruments, the surgeon can repair any damage to the labrum and articular cartilage and shave down any bumps or bony spurs. In some more advanced cases, you may need open surgery to repair the damage.