Table 1.

Modified Mankin score used for histological analysis

I. Structure	Grade
Normal	0
Superficial layer disrupted	1
Superficial layer absent	2
Irregular surface	3
Fissures into the middle zone	4
Slight disorganization	5
Fissure into the deep zone	6
Chaotic disorganization	7
II. Cellular abnormalities
Normal	0
Hypocellularity	1
Large clones	2
III. Matrix staining
Normal	0
Staining reduced in middle layer	1
Staining reduced in territorial matrix of middle and deep layer	2
Staining present in interterritorial matrix and reduced in the territorial matrix	3
Staining reduced in both territorial and interterritorial matrices	4
Maximum score	13