Meniscus tears are one of the most common knee injuries, affecting athletes and older adults alike. Each knee has two menisci — C-shaped wedges of fibrocartilage that cushion the joint, distribute load, absorb shock, and help stabilise the knee. MRI is the best non-invasive way to confirm a meniscal tear, classify its type, and guide treatment decisions — whether that is physiotherapy, arthroscopic surgery, or conservative management.
Around 60-70 per 100,000 people in the UK suffer a meniscal tear each year. In younger patients, tears are usually acute and sports-related. In people over 40, degenerative tears are extremely common — MRI studies show meniscal tears in 35% of asymptomatic people over 50.
Anatomy of the Menisci
Each meniscus is a crescent-shaped piece of cartilage sitting on top of the tibia (shin bone):
- Medial meniscus — on the inner side of the knee. Larger, more C-shaped, and less mobile. Attached firmly to the MCL (medial collateral ligament) and joint capsule. More commonly torn because of its reduced mobility.
- Lateral meniscus — on the outer side. More circular, smaller, and more mobile. Less commonly torn in isolation, but frequently damaged alongside ACL injuries.
The menisci have different blood supply zones, which directly affect healing potential:
- Red zone (outer third) — good blood supply. Tears here can heal with repair.
- Red-white zone (middle third) — reduced blood supply. Healing is possible but less reliable.
- White zone (inner third) — no blood supply. Tears here do not heal. Repair is not usually possible; trimming (partial meniscectomy) is the surgical option.
Types of Meniscal Tears on MRI
The radiologist classifies your tear by pattern and location. This matters because different tear types require different treatments:
- Horizontal tear — runs parallel to the tibial surface, splitting the meniscus into upper and lower layers. Common in degenerative tears. Usually trimmed rather than repaired.
- Vertical longitudinal tear — runs along the length of the meniscus. If in the red zone, these can be repaired (stitched).
- Bucket-handle tear — a vertical longitudinal tear where the inner fragment flips into the centre of the joint like a bucket handle. Causes mechanical locking (the knee gets stuck and cannot straighten). Usually needs urgent surgery to reveal the knee and repair or trim the torn fragment.
- Radial tear — runs from the inner edge outwards, perpendicular to the meniscal surface. Disrupts the meniscus's hoop stress function. Difficult to repair.
- Root tear — a tear at the meniscal root attachment to the bone. Functionally equivalent to a total meniscectomy (the meniscus loses its ability to distribute load). Associated with rapid progression of arthritis if untreated. Root repair is possible at specialist centres.
- Complex/degenerative tear — a combination of tear patterns, usually in an older, degenerate meniscus. Most common type in people over 40.
- Meniscal flap tear — a displaced fragment that can catch and cause clicking.
MRI Grading of Meniscal Signal
Radiologists use a grading system for meniscal signal changes:
- Grade 1 — focal increased signal within the meniscus that does not reach the surface. Represents early degeneration, not a tear. No treatment needed.
- Grade 2 — linear increased signal that does not reach the surface. More advanced degeneration but still not a true tear.
- Grade 3 — increased signal that reaches the articular surface on at least two images. This is a true tear.
What MRI Cannot Tell You
- Whether the tear is causing your pain — degenerative meniscal tears are found in 35% of pain-free people over 50. A tear on MRI in an older patient may be an incidental finding, not the pain source.
- Tissue quality — MRI can show a tear but cannot fully assess how healthy the remaining meniscal tissue is. This is better assessed arthroscopically.
- Exact reparability — the decision to repair vs trim is often made during arthroscopic surgery based on the tear pattern, tissue quality, and blood supply as seen directly.
What to Expect During the Scan
A knee MRI takes 25-35 minutes. Your knee is placed in a coil with your leg slightly bent. Only the lower body enters the scanner. The main sequences used are proton-density fat-saturated (PD FS) in sagittal, coronal, and axial planes. Meniscal tears are assessed primarily on sagittal and coronal images.
Treatment Pathways
Conservative Management
Many meniscal tears — particularly degenerative tears in patients over 40 — respond well to physiotherapy. A landmark trial (FIDELITY, published in the BMJ) showed that for degenerative meniscal tears, physiotherapy was as effective as arthroscopic surgery at 2 years. This has shifted practice significantly.
Conservative management includes:
- Physiotherapy — strengthening quadriceps and hamstrings, improving proprioception
- Activity modification — avoiding deep squatting, twisting movements
- Anti-inflammatory medication (NSAIDs) for pain and swelling
- Corticosteroid injection — can reduce inflammation and provide temporary relief
Arthroscopic Surgery
Surgery is recommended for:
- Bucket-handle tears causing locking
- Tears with persistent mechanical symptoms (catching, clicking, giving way) not responding to physiotherapy
- Acute tears in young patients, particularly if combined with ACL injury
- Root tears in younger patients (to prevent accelerated arthritis)
Surgical options:
- Partial meniscectomy — trimming the torn fragment. Day case surgery, return to normal activities in 2-4 weeks. Effective for symptom relief but removes meniscal tissue, which may increase long-term arthritis risk.
- Meniscal repair — stitching the tear. Preserves the meniscus. Longer recovery (3-6 months, with protected weight-bearing and restricted bending). Better long-term joint health. Only possible for tears in the red zone (outer third) with good tissue quality.
- Meniscal transplant — replacing a removed meniscus with donor tissue. Available at specialist centres for young patients who have had a total meniscectomy and are developing early arthritis.
UK Statistics
- Approximately 60-70 meniscal tears per 100,000 people per year
- Medial meniscus tears are roughly twice as common as lateral tears
- 35% of asymptomatic adults over 50 have meniscal tears on MRI
- Around 50,000 arthroscopic meniscal procedures are performed annually in the UK
- MRI sensitivity for meniscal tears is approximately 90-95%
Frequently Asked Questions
Can a meniscal tear heal on its own?
Small tears in the outer (red) zone with good blood supply can heal. Tears in the inner (white) zone cannot heal because there is no blood supply. Degenerative tears generally do not heal but many become asymptomatic with time and physiotherapy.
How accurate is MRI for meniscal tears?
MRI has a sensitivity of around 90-95% for meniscal tears. False positives can occur, particularly in older patients where degenerative signal changes (grade 2) are misread as tears. False negatives are uncommon but can happen with small radial tears or tears at the meniscal root.
Do all meniscal tears need surgery?
No. Many tears — particularly degenerative tears in older patients — do well with physiotherapy alone. Surgery is reserved for tears causing mechanical locking, persistent symptoms despite conservative treatment, or specific tear types (bucket-handle, root tears) in younger patients.
How much does a knee MRI cost?
Through Lola Health, a knee MRI starts from £275.
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