## Medial vs Lateral Meniscus Mobility **Key Point:** The medial meniscus has firm, broad attachments to the joint capsule and the medial collateral ligament, which restricts its mobility during knee rotation. This fixed position makes it susceptible to being trapped and torn during combined flexion-rotation movements. **High-Yield:** Anatomical differences between medial and lateral menisci: | Feature | Medial Meniscus | Lateral Meniscus | | --- | --- | --- | | Capsular attachment | Firm, broad, extensive | Loose, minimal | | MCL/LCL attachment | Firmly attached to MCL | Loosely attached to LCL | | Mobility | Restricted | Greater freedom of movement | | Injury pattern | Trapped during rotation → tear | Can escape from load → less injury | | Shape | C-shaped (semicircular) | O-shaped (more circular) | **Clinical Pearl:** The "unhappy triad" or "terrible triad" involves ACL, MCL, and medial meniscus injury because the medial structures are tethered together. The medial meniscus cannot escape the compressive load during flexion-rotation, leading to entrapment and longitudinal ("bucket-handle") tears. **Mnemonic:** **FIRM MEDIAL** — Fixed Attachments, Internal Rotation Mechanism, Restricted Mobility, Medial Meniscus Entrapment During Axial Loading, Ligament Coupling ## Mechanism of Injury During flexion-rotation: 1. Knee flexes while tibia rotates internally 2. Medial meniscus attempts to move but is held back by capsular and MCL attachments 3. Femoral condyle continues to move, trapping the meniscus 4. Longitudinal tear results (bucket-handle tear) 
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