Table 2.

O'Driscoll histological cartilage repair score.

Characteristics	Score
Nature of predominant tissue
Cellular morphology
Hyaline articular cartilage	4
Incompletely differentiated mesenchyme	2
Fibrous tissue or bone	0
Safranin-O staining of the matrix
Normal or nearly normal	3
Moderate	2
Slight	1
None	0
Structural characteristics
Surface regularity
Smooth and intact	3
Superficial horizontal lamination	2
Fissures 25–100% of the thickness	1
Severe disruption including fibrillation	0
Structural integrity
Normal	2
Slight disruption including cysts	1
Severe disintegration	0
Thickness
100% of normal adjacent cartilage	2
50–100% of normal cartilage	1
0–50% of normal cartilage	0
Bonding to the adjacent cartilage
Bonded at both ends of graft	2
Bonded at one end or partially at both ends	1
Not bonded	0
Freedom from cellular changes of degeneration
Hypocellularity
Normal cellularity	3
Slight hypocellularity	2
Moderate hypocellularity	1
Severe hypocellularity	0
Chondrocyte clustering
No clusters	2
<25% of the cells	1
25–100% of the cells	0
Freedom from degenerative changes in adjacent cartilage
Normal cellularity, no clusters, and normal staining	3
Normal cellularity, mild clusters, and slight staining	2
Mild or moderate hypocellularity, slight staining	1
Severe hypocellularity, poor or no staining	0
Total	24