Table 1.

Modified Outerbridge Classification

Grade	Magnetic Resonance Imaging Characteristics
0	Normal articular cartilage
1	Focal areas of hyperintensity within the normal contour
2	Fissure or blister-like swelling of articular cartilage extending to the surface
3	Focal ulcerations of the articular cartilage
4	Full-thickness cartilage loss with underlying bone reactive changes