Table III.

O'Driscoll's microscopic histological evaluation of articular cartilage.

Variable	Score
Tissue morphology
Mostly hyaline cartilage	4
Mostly fibrocartilage	3
Mostly non-cartilage	2
Exclusively non-cartilage	1
Matrix staining
None	1
Slight	2
Moderate	3
Strong	4
Structural integrity
Severe disintegration	1
Cysts or disruption	2
No organization of chondrocytes	3
Beginning of columnar organization of chondrocytes	4
Normal, similar to healthy mature cartilage	5
Chondrocyte clustering in implant
25–100% of cells clustered	1
<25% of cells clustered	2
No clusters	3
Intactness of calcified layer; tidemark formation
<25% of calcified layer intact	1
25–49% of calcified layer intact	2
50–75% of calcified layer intact	3
76–90% of calcified layer intact	4
Complete intactness of calcified cartilage layer	5
Subchondral bone formation
No formation	1
Slight	2
Strong	3
Histological assessment of surface architecture
Severe fibrillation of disruption	1
Moderate fibrillation or irregularity	2
Slight fibrillation or irregularity	3
Normal	4
Histological assessment of defect filling
<25%	1
26–50%	2
51–75%	3
76–90%	4
91–110%	5
Lateral integration of implanted material
Not bonded	1
Bonded at one hand/partially at both ends	2
Bonded at both sides	3
Basal integration of implanted material
<50%	1
50–70%	2
70–90%	3
91–100%	4
Inflammation:
No inflammation	1
Slight inflammation	3
Strong inflammation	5
Maximum total score	45