Knee X-rays and MRI scans: what to expect

X-ray or MRI: why one and not the other

The two tests answer different questions. An X-ray shows bone: fractures, the gap between the bones, which gives an indirect idea of cartilage thickness, bone spurs from arthritis, the position of the kneecap and loose fragments. An MRI shows soft tissue: the cruciate and collateral ligaments, the meniscus, cartilage surfaces, tendons, bone bruising and fluid.

Not every knee needs a scan. Dr. Pablo Gelber examines the knee first and usually requests imaging only when the result is likely to change the plan. For a younger patient with a twisting injury, that is often an MRI. For knee pain from middle age onwards, standing X-rays usually come first, because arthritis is judged more accurately with the joint carrying your weight. If imaging is needed, the team at Aman Hospital will explain how and where it will be arranged.

Having a knee X-ray

A knee X-ray is quick, usually a few minutes in the room. You may be asked to stand for some views, bend the knee for others, and sometimes to have both knees taken together for comparison. Standing views matter: a knee can look normal lying down and show clear narrowing when you stand.

The radiation dose from a knee X-ray is low. If you are or might be pregnant, tell the radiographer before the images are taken.

Having a knee MRI

For a knee MRI you lie on your back with the knee inside a padded coil, and the table slides into the scanner. Most knee scans are done feet first with the knee in the centre of the machine, so your head and upper body are often near or outside the opening, which many patients find easier than they expected. The scan usually takes around 20 to 40 minutes, depending on the scanner and the images needed, and keeping completely still gives the clearest images.

The machine is loud, with knocking and buzzing sounds, so you will be given ear protection. You can talk to the radiographer through an intercom and use a call button at any time. You do not usually need to fast, and a contrast injection is rarely needed for a routine knee MRI. Wear comfortable clothes without metal, or change into a gown.

Metal and safety questions

An MRI uses a strong magnet, so safety screening is essential. You will fill in a questionnaire, and it matters that you answer it carefully. Tell the team before the scan if you have:

• A pacemaker, defibrillator or other implanted heart device.
• A cochlear implant, nerve stimulator, insulin pump or other electronic implant.
• Clips on blood vessels in the brain from previous surgery.
• Metal fragments in the eye, including from welding, grinding or metalwork, a particular concern if you have worked in industrial jobs.
• Shrapnel or bullet fragments.
• Pregnancy or possible pregnancy.

Most modern orthopaedic implants, such as knee replacements, screws and plates, can usually be scanned safely, but mention them anyway; the radiology team checks each implant, and metal near the knee can blur the images. Remove jewellery, watches, hair clips, hijab pins, hearing aids and anything with metal fastenings, mention any medicine patches on your skin, and leave cards and phones outside the room.

If you feel claustrophobic

Say so when the scan is booked, not on the day. Simple steps help many people: knowing that most knee scans go in feet first, keeping your eyes closed, slow breathing, and having the radiographer talk you through each sequence. Some patients bring someone to wait just outside. If anxiety is severe, discuss options with your doctor in advance rather than taking anything on your own.

Bringing scans from another hospital

If you had an MRI or X-ray elsewhere in Qatar or abroad, bring it. A recent, good-quality MRI may avoid a repeat scan. What is useful:

• The full images on a disc or USB drive, or a download link, not only photos of a screen.
• The written radiology report.
• The date of the scan, which matters because injuries change over weeks and months.

Dr. Gelber looks at the images himself and relates them to your examination. Sometimes an older scan no longer reflects the knee, or the images are not detailed enough, and a new one is suggested.