Hip impingement

What is hip impingement?

Hip impingement happens when the ball at the top of your thigh bone and the socket in your pelvis don't move smoothly together because extra bone on one or both sides causes them to catch and rub. Over time, this can damage the ring of cartilage lining the socket, called the labrum, and the smooth cartilage covering the joint surfaces.

Symptoms of hip impingement

Some people have these bone changes that cause hip impingement for years without any pain. When symptoms do appear, the most common is a deep, on-and-off ache in the groin, felt during or after activity.

You might also notice:

• catching or pinching in the groin
• pain down the front of your thigh, or occasionally at the outer hip, buttock or lower back
• a feeling that your hip might give way
• pain when running, changing direction quickly, twisting or making a sudden explosive movement
• pain when bringing your knee towards your chest or squatting deeply, such as when tying your shoelaces
• discomfort after sprinting, kicking sports, hill walking, or sitting for a long time in a low chair.

Causes of hip impingement and who is at risk

Hip impingement develops when the ball or socket of the hip is a slightly different shape to normal, so the two surfaces catch against each other during movement. It is not fully understood whether people are born with this shape or develop it later, and it is likely that genetics and physical activity both play a part.

You may be more likely to develop hip impingement if you:

• are young and play a lot of sport, particularly football, rugby, gymnastics or other activities involving repeated twisting or kicking
• did intense, rotational sport during your teenage years, while your bones were still developing
• have weaker or less coordinated muscles around the hip, which increases stress on the joint
• carry excess weight

Hip impingement is common. 10–15% of adults have the bony changes that can cause it, rising to over half of athletes who have hip symptoms.

Are there different types of hip impingement?

There are three types of hip impingement, depending on where the extra bone is:

• Cam impingement, where the ball of the joint isn't perfectly round, so its edge catches on the socket
• Pincer impingement, where the socket is deeper than normal, or has extra bone over its edge, so it catches on the neck of the thigh bone
• Mixed, or combined, impingement, where both the ball and socket are affected.

Cam impingement is the most common cause of hip impingement, and many people have a mix of both types.

How hip impingement is diagnosed

Your doctor or physiotherapist will ask about your symptoms and examine how your hip moves. They will check your walking pattern, hip strength and range of movement, and may, with your consent, bend, rotate or bring your knee towards your chest to see if this brings on or aggravates your pain.

You may need an Xray of your hip to check the shape of the bones or you may be recommended to have a CT scan or an MRI scan for more detailed images of the joint and surrounding soft tissues.

How hip impingement is treated

Most people try non-surgical treatment first, and surgery is only considered if this doesn't help enough.

Non-surgical treatment

Options to manage hip impingement without surgery include:

• changing or reducing activities that bring on your pain, such as deep squats, heavy lifting, or fast running on hard ground
• losing weight if you're carrying excess weight, since this can significantly ease symptoms
• physiotherapy exercises to strengthen the muscles around your hip and improve core stability, which can take 3–6 months to show improvement
• regular moderate exercise, such as brisk walking, cycling, swimming, pilates or yoga, adapted to avoid painful movements
• painkillers such as paracetamol, or anti-inflammatories like ibuprofen; if you are able to take them. Speak to your GP if you need to take these for more than 10 days
• a steroid injection into the hip joint, which can ease pain and help you get more from physiotherapy.

Surgical treatment

If non-surgical treatment doesn't help enough and your symptoms are affecting your daily life, your surgeon may suggest hip arthroscopy, a type of keyhole surgery. During this procedure, your surgeon may need to:

1. shave down the excess bone causing the impingement, on the ball, the socket, or both
2. repair or trim any tears in the labrum, the ring of cartilage around the socket
3. treat any damage to the smooth cartilage lining the joint, if needed.

Research shows surgery is only slightly more effective than physiotherapy alone. After a year, people who've had surgery report being around 60% better on average, compared with around 50% for those who have physiotherapy, so a good period of rehabilitation is usually recommended first, since surgery carries more risk.

After surgery, you'll usually need to limit how much weight you put on your leg for 2–6 weeks. Gentle movement exercises start early, and you'll gradually build up to strengthening, balance and, eventually, running or jumping over the following weeks.

If you already have arthritis in your hip, this surgery is unlikely to help, and a hip replacement may be a better option.

When to see a doctor

See your GP or physiotherapist if:

• your hip pain doesn't improve with rest and simple self-care
• pain is affecting your daily activities, sport or sleep
• your hip catches, locks, or gives way
• you need to take ibuprofen for more than 10 days or simple painkillers do not control your pain.

If ongoing pain is affecting your mood, it's worth talking to your physiotherapist or GP about this too.