Table 1. Histological grading scale for defects in articular cartilage.

Category		Score (Points)
1.	Filling of defect relative to surface of
	normal adjacent cartilage	0
	>90%	1
	75-90%	2
	50-74%	3
	25-49%	4
	<25%
2.	Cellular morphology (percentage of
	chondrocytes)	0
	>90%	1
	75-90%	2
	50-74%	3
	25-49%	4
	Mostly fibroblast-like cells
3.	Surface architecture
	Normal	0
	Slightly irregular	1
	Fibrillation	2
	Distrupted	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
5.	Integration of repair tissue with adjacent
	articular cartilage	0
	Normal	1
	Decreased cellularity	2
	Small gap	3
	Discontinuity
7.	Percentage of new subchondral bone
	>90%	0
	75-90%	1
	50-74%	2
	25-49%	3
	<25%	4