Medically reviewed by Prof. Dr. Aamer Nadeem Chaudhary, M.B.B.S., D.M.R.D., F.C.P.S. (Diagnostic Radiology), Consultant, Al-Nasar Lab & Diagnostic Centre. Updated September 2026.
Quick answer: A knee MRI is the best test for soft tissue inside the knee. It shows the ACL, PCL, meniscus, collateral ligaments, cartilage and tendons, none of which appear on an X-ray. It takes roughly 20 to 40 minutes, uses no radiation, and most knee MRI scans need no injection at all.
Book a knee MRI: call 0300 0341944. MRI is performed at our main Johar Town campus.
Why is an X-ray not enough for a knee injury?
This is the most common question, and the answer is simple. An X-ray is excellent at showing bone. It will reveal a fracture, joint space narrowing from arthritis, or a bony fragment.
But the structures that actually tear in a sporting knee injury, the ligaments and the meniscus, are soft tissue. They are effectively invisible on X-ray. A completely normal knee X-ray is entirely compatible with a fully torn ACL.
MRI uses a magnetic field rather than radiation, and it distinguishes between different soft tissues with great clarity. That is why it is the standard test for internal knee derangement.
What can a knee MRI detect?
| Structure | Common problem found | How the injury usually happens |
|---|---|---|
| ACL (anterior cruciate ligament) | Partial or complete tear | Twisting on a planted foot, often with a popping sound |
| Meniscus | Tear, bucket handle tear, degenerative fraying | Twisting injury in the young, gradual wear in older adults |
| PCL | Tear | Direct blow to the front of a bent knee, common in road accidents |
| Collateral ligaments (MCL, LCL) | Sprain or tear | Force applied to the side of the knee |
| Articular cartilage | Thinning, defects, early arthritis | Wear over time, or after injury |
| Patellar and quadriceps tendon | Tendonitis, partial tear | Overuse, jumping sports |
| Bone | Bone bruise, stress fracture, marrow oedema | Often invisible on X-ray but clearly seen on MRI |
| Joint lining | Effusion, Baker cyst, synovitis, infection | Injury, inflammation or arthritis |
When should you have a knee MRI?
- The knee gave way or felt unstable during or after an injury
- You heard or felt a pop at the moment of injury, which is characteristic of an ACL tear
- The knee locks, catches or will not straighten fully, which suggests a meniscal tear
- Significant swelling within a few hours of injury, indicating bleeding into the joint
- Pain persisting beyond a few weeks despite rest and physiotherapy
- A normal X-ray but continuing symptoms
- Before knee surgery, to plan the procedure precisely
- Suspected infection, tumour or unexplained bone pain
What actually happens during the scan?
You lie on a padded table, feet first, and only your legs and lower body enter the scanner. Your head usually stays outside, which reassures most people who are anxious about enclosed spaces.
A padded coil is placed around the knee. This is a receiver, not a restraint, and it is what produces the image detail. The technologist positions the knee carefully, because even small movements blur the images and can force a repeat sequence.
The scanner is loud, producing repeated knocking and buzzing sounds as the sequences run. Ear protection is provided. Each sequence lasts a few minutes and you are asked to stay still throughout, though you can talk to the technologist between sequences and you have a call button at all times.
Total time is usually 20 to 40 minutes. There is no pain and no radiation.
Do you need contrast for a knee MRI?
Usually not. The great majority of knee MRI scans, including those for suspected ACL and meniscal tears, are done without any injection.
Contrast is added in specific situations: when infection or a tumour is suspected, when inflammatory arthritis is being assessed, or in an MR arthrogram, where dilute contrast is injected directly into the joint. That last one is mainly used when a previous meniscal repair makes it hard to tell old surgery from a fresh tear.
Who should not have an MRI?
MRI uses a strong magnet, so certain implants matter. Tell the radiology team before your appointment if you have:
- A pacemaker or implanted defibrillator, unless it is a documented MRI conditional device
- A cochlear implant or certain neurostimulators
- Older aneurysm clips in the brain
- Any metal fragment in the eye, which is important for anyone with a history of metal grinding work
- Recently placed surgical implants, which need checking rather than automatically excluding you
Most modern orthopaedic implants, including knee replacements, plates and screws, are MRI safe, though metal near the knee can cause local image distortion. Bring the implant card if you have one.
How to prepare
- No fasting is needed for a routine knee MRI, and you can take your usual medicines
- Wear comfortable clothing without metal. You may be given a gown
- Leave jewellery, watches and hairpins at home or with an attendant
- Bring previous X-rays, MRI reports and your referral letter, since comparison improves accuracy
- If you struggle with enclosed spaces, mention it when booking. Feet first positioning helps considerably
- Arrive a little early to complete the safety questionnaire
Knee MRI at Al-Nasar Lab
Al-Nasar Lab & Diagnostic Centre has served Lahore since 1996 and holds ISO 15189:2022 accreditation from the Pakistan National Accreditation Council. MRI at our Johar Town campus is reported by consultant radiologists, with reports delivered digitally and images available for your orthopaedic surgeon.
If you are unsure which scan you need, our team can guide you based on your referral. Related reading: MRI or CT, which do you need, is MRI safe and what to expect, and MRI for back pain and slipped disc.
Contact us to book or find your nearest location.
Frequently Asked Questions
How long does a knee MRI take?
Usually 20 to 40 minutes, depending on how many sequences are needed and whether contrast is used.
Does a knee MRI hurt?
No. The scan itself is painless. The main challenge is staying still on a firm table while the scanner makes loud knocking sounds, and ear protection is provided.
Will my head go inside the scanner?
Generally no. For a knee scan you go in feet first and your head usually remains outside the bore, which makes it much easier for anyone uneasy in enclosed spaces.
Can an MRI show an ACL tear?
Yes. MRI is the standard test for diagnosing ACL tears and distinguishing partial from complete tears, which is information an X-ray cannot provide.
Can I have a knee MRI with a knee replacement?
Usually yes, most modern implants are MRI safe, though metal can distort nearby images. Tell the radiology team what you have and bring your implant card if available.
This article is for general information and is not a substitute for medical advice. Please discuss your results with a qualified doctor.
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