Table 2 Modified Histological Grading Scale for Defects in Articular Cartilage 3

1. Filling of defect relative to surface of normal adjacent cartilage

   > 90%

0

   75-90%

1

   50-74%

2

   25-29%

3

   < 25%

4

2. Cellular morphology (percentage of chondrocytes)

   > 90%

0

   75-90%

1

   50-74%

2

   25-49%

3

   Mostly fibroblast-like cells

4

3. Surface architecture

   Normal

0

   Slightly irregular

1

   Fibrillation

2

   Disrupted

3

4. Matrix staining with Safranin O

   Normal

0

   Slightly reduced

1

   Moderately reduced

2

   Substantially reduced

3

   None

4

5. Tidemark formation

   > 90%

0

   75-90%

1

   50-74%

2

   25-49%

3

   < 25%

4

6. Integration of repair tissue with adjacent articular cartilage

   Normal

0

   Decreased cellularity

1

   Small gap

2

   Discontinuity

3

7. Percentage of new subchondral bone

   > 90%

0

   75-90%

1

   50-79%

2

   25-49%

3

   < 25%

4