Hip Impingement

Hip impingement, also known as femoroacetabular impingement (FAI), occurs when the bones of the hip joint abnormally rub against each other. This happens because the hip bones have an irregular shape, which can damage the joint's cartilage and soft tissues over time. It often causes pain and stiffness, especially during movement.

What is Hip Impingement?

Hip impingement (femoroacetabular impingement or FAI) is a condition where the ball (femoral head) and socket (acetabulum) of the hip joint do not fit together perfectly. This abnormal contact causes the bones to rub against each other, leading to damage of the joint's smooth cartilage and surrounding soft tissues.

The hip is a ball-and-socket joint. In hip impingement, extra bone grows on either the ball (femoral head) or the socket (acetabulum), or sometimes both. This extra bone causes the hip bones to collide when you move your leg, particularly during bending or rotating movements. There are three main types of hip impingement. Cam impingement occurs when the femoral head is not perfectly round, causing it to grind against the cartilage inside the socket. Pincer impingement happens when the socket has too much bone covering the femoral head, leading to the labrum (a ring of cartilage around the socket) being pinched. Mixed impingement, the most common type, involves features of both cam and pincer impingement. Over time, this repeated rubbing can lead to pain, stiffness, and potentially damage to the joint cartilage and the labrum, increasing the risk of developing hip osteoarthritis.

Symptoms

The main symptom of hip impingement is pain in the groin area, especially during or after activities that involve bending the hip. You might also feel stiffness in the hip joint or a limited range of motion. These symptoms often develop gradually and can worsen over time.

Pain from hip impingement is typically felt in the front of the hip or groin, but it can sometimes spread to the outside of the hip or even the buttocks. This pain often flares up with activities like sitting for long periods, walking uphill, running, squatting, or turning the hip. Besides pain, you may notice a feeling of stiffness in your hip, which can make it harder to move your leg freely. Some people also experience a clicking, locking, or catching sensation within the hip joint. Initially, symptoms might be mild and intermittent, but they can become more constant and severe as the condition progresses and more damage occurs to the joint structures.

Causes & risk factors

Hip impingement is primarily caused by the abnormal shape of the hip bones, which is often present from birth or develops during childhood growth. While the exact reason for these bone shapes isn't always clear, certain activities and genetics can increase the risk of developing symptoms.

The irregular bone shapes that cause hip impingement usually develop during the growth years of childhood and adolescence. For example, if the top of the thigh bone (femur) grows with an extra bump, or if the hip socket (acetabulum) has an overgrowth of bone, these can lead to impingement. While the bone structure is the primary cause, certain activities can act as risk factors for developing symptoms or worsening the condition. Athletes, especially those involved in sports requiring extreme hip motion like hockey, soccer, football, golf, and dance, may be more prone to experiencing symptoms due to repetitive stress on the hip joint. However, hip impingement can affect anyone, not just athletes. The long-term effects of untreated hip impingement can include damage to the labrum and cartilage, potentially leading to hip osteoarthritis.

How it's diagnosed

Diagnosing hip impingement typically involves a physical exam, where your doctor will assess your hip's range of motion and check for pain with specific movements. Imaging tests, such as X-rays, MRI scans, or CT scans, are then used to confirm the diagnosis and visualize the abnormal bone shapes.

During the physical exam, your doctor will ask about your symptoms and medical history. They will move your leg in various directions to see if certain positions cause pain or if your hip's range of motion is limited. A common test involves bending your hip to 90 degrees and rotating it inward, which often reproduces impingement pain. Imaging tests are crucial for confirming hip impingement. X-rays can show the abnormal bone shapes on the femoral head or acetabulum. Magnetic resonance imaging (MRI) provides detailed images of the soft tissues, such as the labrum and cartilage, to check for damage. Sometimes, a CT scan may be used to get a more precise 3D view of the bone structure. These tests help your doctor understand the extent of the impingement and plan the most appropriate treatment.

Treatment options

Treatment for hip impingement usually begins with conservative methods to manage pain and improve hip function. These include rest, activity modification, physical therapy, and pain relievers. If conservative treatments are not effective, surgery may be recommended to reshape the hip bones.

Initial treatment often focuses on reducing pain and preventing further damage. Your doctor may advise you to avoid activities that worsen your pain, such as deep squatting or prolonged sitting. Over-the-counter pain relievers, like ibuprofen or naproxen, can help manage discomfort. In some cases, corticosteroid injections may be used to reduce inflammation and pain temporarily. Physical therapy is a key part of conservative treatment. A physical therapist can teach you exercises to strengthen the muscles supporting your hip, improve your range of motion, and correct movement patterns that contribute to impingement. If conservative treatments do not provide enough relief, surgery, typically hip arthroscopy, may be considered. During this minimally invasive procedure, a surgeon uses small incisions and a camera to reshape the bones, repair the labrum, and remove any damaged cartilage, aiming to restore normal hip mechanics.

Recovery & outlook

Recovery from hip impingement, whether treated conservatively or surgically, involves a period of rehabilitation to regain strength and mobility. The outlook is generally positive, with many people experiencing significant pain relief and improved function, especially when the condition is diagnosed and treated early.

For those undergoing conservative treatment, consistent physical therapy and adherence to activity modifications are essential for a good recovery. It may take several weeks or months to notice significant improvement in pain and function. Following hip arthroscopy, recovery typically involves crutches for a few weeks and a structured physical therapy program that can last several months. The goal of rehabilitation is to gradually restore strength, flexibility, and normal movement patterns. While surgery can effectively relieve pain and improve hip function, it does not eliminate the risk of developing hip osteoarthritis later in life, especially if significant cartilage damage was already present. However, by correcting the impingement, surgery aims to reduce the progression of joint damage and improve long-term hip health.

When to see a doctor

You should see a doctor if you experience persistent hip or groin pain that does not improve with rest or over-the-counter pain relievers, especially if it limits your daily activities. Early diagnosis and treatment of hip impingement can help prevent further joint damage.

It's important to seek medical attention if your hip pain is severe, suddenly worsens, or is accompanied by a locking or catching sensation in the joint. If you find that you are consistently modifying your activities to avoid pain, or if your range of motion is noticeably limited, these are also signs to consult a healthcare professional. While hip impingement is not typically an emergency, ignoring persistent hip pain can lead to more extensive damage to the joint's cartilage and labrum, potentially increasing the risk of developing osteoarthritis. A doctor can properly diagnose the cause of your hip pain and recommend the most appropriate treatment plan to protect your hip joint.

Frequently asked questions

Can hip impingement heal on its own?

Hip impingement, caused by abnormal bone shapes, typically does not heal on its own. While symptoms might temporarily improve with rest or activity modification, the underlying bone structure remains. Without addressing the impingement, the rubbing can continue to cause pain and potentially lead to further joint damage over time.

What activities should I avoid with hip impingement?

If you have hip impingement, you should generally avoid activities that involve deep hip flexion (bending the hip past 90 degrees), internal rotation, or prolonged sitting, as these can increase impingement and pain. Examples include deep squats, lunges, certain yoga poses, and high-impact sports that require quick turns or extreme hip movements. Your doctor or physical therapist can provide specific guidance.

Is walking good or bad for hip impingement?

Walking is generally considered a low-impact activity and can be beneficial for maintaining hip mobility and muscle strength. However, if walking, especially uphill or for long distances, causes pain, it's best to modify your activity or discuss it with your doctor. The goal is to stay active without aggravating your symptoms.

How long does it take to recover from hip impingement surgery?

Recovery from hip impingement surgery (arthroscopy) typically involves several weeks on crutches, followed by a structured physical therapy program that can last from three to six months, or even longer. Full return to sports or strenuous activities may take six months to a year, depending on the individual and the extent of the surgery.

Can hip impingement lead to arthritis?

Yes, hip impingement can increase the risk of developing hip osteoarthritis (arthritis). The repeated rubbing of abnormally shaped bones can damage the smooth cartilage that covers the joint surfaces and tear the labrum. Over time, this damage can lead to the wear and tear characteristic of osteoarthritis.

Are there exercises I can do for hip impingement?

Yes, specific exercises can help manage hip impingement symptoms by strengthening the muscles around the hip, improving core stability, and enhancing hip mobility without causing impingement. A physical therapist can design a personalized exercise program for you, focusing on gentle stretches and strengthening exercises that avoid painful movements.

Sources

• MedlinePlus — Hip Impingement
• Mayo Clinic — Hip Impingement
• Cochrane Library — Hip Impingement