About a hip MR arthrogram
The hip is a ball-and-socket joint. The socket (acetabulum) is lined by a rim of cartilage called the labrum, which deepens the socket and helps keep the joint stable. Tears of the labrum can cause pain in the groin, buttock or thigh, along with clicking, locking, catching or a feeling of the hip giving way.
Labral tears are often linked to femoroacetabular impingement (FAI), where the shape of the ball (cam type) or the socket (pincer type) causes them to rub together abnormally when the hip bends and twists. Cam impingement is more common in young, active men, and pincer impingement in middle-aged active women.
In an MR arthrogram, contrast dye is injected into the hip joint before the MRI scan. The dye fills the joint and outlines the labrum and cartilage, which can show tears more clearly than a standard MRI. It is usually requested by an orthopaedic surgeon or sports medicine specialist to help decide whether treatment such as hip arthroscopy (keyhole surgery) may help. Left and right hips are separate scans.
What happens during the scan
An MR arthrogram is done in two parts. First, a small amount of contrast dye (gadolinium) is injected directly into the hip joint. The skin is cleaned and numbed with local anaesthetic, and the needle is guided into the joint using X-ray (fluoroscopy) or ultrasound. You may feel a sharp scratch, some pressure and a feeling of fullness in the joint, but it should not be painful. You will then be asked to move the joint gently to spread the dye.
Shortly afterwards you have the MRI scan. You lie still on the scanner bed with the hip in a coil while the pictures are taken; the scan itself usually takes about 20–40 minutes. The scanner is loud, so you will wear ear plugs or headphones, and the radiographer can talk to you throughout. Allow up to 1½ hours for the whole appointment.
Referral needed: this scan requires a referral from a specialist, such as an orthopaedic surgeon, sports medicine doctor or specialist physiotherapist. You can upload the referral when you book.
Some centres also inject local anaesthetic into the hip at the same time. If your pain improves for a few hours afterwards, it suggests the pain is coming from inside the joint, so keep a note of how your hip feels and tell your specialist.
What the scan can show
A hip MR arthrogram can help to look at:
- tears and fraying of the labrum
- signs of femoroacetabular impingement (cam or pincer shape)
- damage to the joint cartilage, although small cartilage changes can be harder to see than labral tears
- persistent, unexplained hip or groin pain
- the joint before or after hip arthroscopy
Your specialist will look at the scan together with your symptoms and examination, as no scan picks up every tear.
Preparing for your scan
No special preparation is usually needed, and you can eat and drink normally. Because the injection goes into a joint, tell us when booking if you take blood-thinning medicines, have a skin infection near the joint, have kidney problems or have had a reaction to contrast dye. Arrange for someone else to drive you home, as you should not drive for 24 hours afterwards.
You can usually eat, drink and take your normal medicines unless the scanning centre tells you otherwise. Wear loose, comfortable clothing without metal zips or buttons, and leave jewellery at home. You will be asked to remove metal items such as hair clips, hearing aids, coins and keys, and you may be asked to change into a gown.
Before the scan you will complete a safety questionnaire. Tell the team if you have a pacemaker, any metal implant, surgical clips or other device, if you have kidney problems or allergies, or if you are, or might be, pregnant or breastfeeding. If you feel anxious in enclosed spaces, let us know when you book. Some centres can offer a relaxant, and if you take one you will need someone to take you home and must not drive for 24 hours.
After the arthrogram
The joint may feel stiff, swollen or full, and you may hear it creak or gurgle as you move it. This usually settles within 48 hours. Keep the joint moving gently, but avoid vigorous exercise for at least 24 hours. An ice pack and a simple painkiller can help. Do not drive for 24 hours after the injection. Contact your GP or NHS 111 if the joint becomes increasingly painful, red, hot or swollen, or if you develop a fever, as infection, although rare, needs prompt treatment.
Frequently asked questions
Do I need a referral for an MR arthrogram of the hip?
Yes. This scan requires a referral from a specialist. Please upload your referral when you book so the scanning centre can check that an arthrogram is the right test for you.
What is the difference between an MRI and an MR arthrogram?
A standard MRI is taken without anything being injected into the joint. In an MR arthrogram, contrast dye is injected into the joint first. The dye fills the joint and outlines the cartilage, ligaments and other structures, which can show small tears that a standard MRI may not.
Is the injection painful?
The skin is numbed with local anaesthetic first, so most people feel only a sharp scratch and some pressure. The joint may feel full or stiff for a day or two afterwards.
Can I drive home afterwards?
No. You should not drive for 24 hours after the injection, so please arrange for someone to take you home.
What is a hip labral tear?
The labrum is a ring of cartilage around the rim of the hip socket. A tear can cause groin, buttock or thigh pain, clicking, locking or catching. Tears are often linked to hip impingement, where the ball and socket rub together abnormally.
Sources
- RadiologyInfo.org – Arthrography
- United Lincolnshire Hospitals NHS – MRI Arthrogram
- Brigham and Women’s Hospital – Hip labral tear (patient information)
- Dorset County Hospital NHS – MR arthrogram information
- NHS – MRI scan
The information on this page has been gathered from various sources and is provided for general information only. It is not medical advice. TOP MRI is not liable for the accuracy or completeness of this information. Please speak to your doctor or the scanning centre about your own situation.