Table 1.

Histological damage grading system.

Category	Subcategory	Score
Macroscopic superficial damage (irregularities and clefts)	No irregularities	0
	Surface irregularities	1
	Surface damage	2
	Clefts to transitional zone	3
	Clefts to radial zone	4
	Clefts to calcified zone	5
Microscopic internal damage (visualized by col2-3/4m staining)	No staining	0
	¼ of the cartilage thickness	1
	½ of the cartilage thickness	2
	¾ of the cartilage thickness	3
	Full thickness cartilage	4
	No superficial zone staining	+ 0
	Superficial zone staining	+ 1
Total		0–10