Ultrasonographic evaluation of medial meniscus extrusion. *Osteophyte, **Medial meniscus, ***Medial femoral epicondyle. Line A was drawn to connect the cortex of both the femur and tibia, thereby tracing the femoral cortex at the bottom of the medial femoral epicondyle. Line B was drawn perpendicularly from the bottom of Line A to the most medially extruded part of the medial meniscus. Line A was drawn through the osteophyte bases to avoid the bony interference of osteophytes throughout the length of Line B. Finally, the length of Line B (mm) was measured as the medial meniscus extrusion.