Knee MRI — Meniscus, Ligaments & Cartilage

Knee MRI

The workhorse joint study — MRI reads the meniscus, ligaments and cartilage, and the same rule applies: a signal change only matters if it reaches a surface or fits the story.

Menisci

A meniscal tear is diagnosed when abnormal signal reaches the articular surface. Intrasubstance high signal that doesn’t reach a surface is usually degeneration, not a surgical tear — a common source of over-calling.

Watch for the bucket-handle tear (displaced fragment; “double PCL” sign) and root tears — both change management.

Ligaments

ACL: discontinuity, abnormal angle/signal; look for the classic pivot-shift bone bruises (lateral femoral condyle + posterolateral tibia) and associated Segond fracture.
PCL & collaterals: assessed for sprain vs complete tear; MCL/LCL and posterolateral corner.

Cartilage & bone

MRI grades chondral defects and detects bone-marrow oedema — seen in acute injury (bone bruise), stress reaction, and subchondral disease. Quantitative cartilage mapping (T2/T1rho) can flag early degeneration before defects appear.

Reference: Nikken JJ, Oei EH. Magnetic resonance imaging of the knee — clinical reviews on meniscal and ligament assessment.

Educational summary for clinicians; correlate with symptoms and examination. Not medical advice.