How to Read Knee MRI

You received a knee MRI report: «chondromalacia grade II», «horizontal tear of the posterior horn of the medial meniscus», «synovitis»… It sounds frightening. But what really requires treatment? We break down each term.

Basics: what knee MRI shows

MRI (magnetic resonance imaging) is the best method for visualizing joint soft tissues. MRI shows:

• Menisci — cartilage «cushions» between the femur and tibia
• Ligaments — anterior and posterior cruciate (ACL, PCL), collateral
• Articular cartilage — covering of joint surfaces
• Synovial membrane — inner joint lining
• Bones — bone marrow edema, cysts, osteophytes
• Muscles and tendons — quadriceps, hamstrings

Menisci: interpretation

Meniscus injury classification (Stoller)

• Grade I — punctate signal inside the meniscus. This is degenerative change, NOT a tear. Treatment usually not required.
• Grade II — linear signal not reaching the meniscus surface. Also not a tear. Norm for people over 40.
• Grade III — signal reaches the meniscus surface. This is a tear. Requires clinical symptom assessment.

Important: Grade I and II are norm after 35–40 years. Do not panic if you see these terms in the report.

Meniscus tear types (Grade III)

• Horizontal — often degenerative. Can be stable and not require treatment.
• Vertical (longitudinal) — often traumatic. If unstable — treatment indicated.
• «Bucket handle» — displaced fragment. Blocks the joint. Requires intervention.
• Radial — disrupts meniscus biomechanics. Frequent indication for regenerative treatment.
• Complex — multiple tear types. Evaluated individually.

Not every meniscus tear requires arthroscopy. Degenerative tears with knee osteoarthritis are often better treated conservatively or regeneratively (details).

Ligaments: ACL and PCL

• "ACL integrity preserved" — normal
• "Heterogeneous ACL signal" — mucoid degeneration or partial injury
• "ACL not visualized" / "complete rupture" — indication for ACL reconstruction if instability present

Partial ligament injuries may heal with regenerative therapy (CGF + MFAT).

Cartilage: Chondromalacia

Chondromalacia — softening and damage to articular cartilage:

• Grade I — cartilage softening (edema). On MRI — signal change, thickness preserved.
• Grade II — superficial fissures (<50% thickness). Early degeneration.
• Grade III — deep fissures (>50% thickness). Significant damage.
• Grade IV — full-thickness defect to bone. "Bone-on-bone".

Grade I–II — respond well to regenerative methods. Grade III — regeneration still possible. Grade IV — effectiveness limited.

Synovitis and Effusion

• "Moderate synovitis" — inflammation of synovial membrane. Common companion of osteoarthritis.
• "Joint effusion" — fluid in the joint. Sign of inflammation.
• "Baker's cyst" — fluid collection in popliteal fossa. Usually a consequence, not the cause of the problem.

Synovitis and effusion are consequences, not the cause. Treat the underlying disease.

Bones: What Findings Mean

• "Bone marrow edema" — bone reaction to overload or trauma. Painful but reversible.
• "Subchondral sclerosis" — bone densification under cartilage. Sign of chronic overload (osteoarthritis).
• "Osteophytes" — bony outgrowths at joint margins. Sign of osteoarthritis.
• "Subchondral cysts" — cavities in bone. Appear in progressive osteoarthritis.

Red Flags: When Urgent Consultation Is Needed

• ?? "Complete ACL rupture" + knee instability
• ?? "Bucket-handle meniscus tear" with locking
• ?? Chondromalacia IV with bone-on-bone
• ?? Avascular necrosis of condyle
• ?? Suspicion of neoplasm

What to Do with Your MRI Report

1. Don't panic — many findings (Grade I–II meniscus, moderate synovitis) are age-related norms
2. Show to orthopedist — MRI without clinical evaluation is meaningless
3. Correlate — symptoms must match MRI findings
4. Get second opinion — if surgery is recommended, request evaluation from another specialist

Related Articles

How to read spine MRI Knee Osteoarthritis: 4 Stages Recovery after Arthroscopy