Table 1 Scoring parameters for histological evaluations (modified O’Driscoll score)
Tissue | Parameters | Score | ||||
|---|---|---|---|---|---|---|
0 | 1 | 2 | 3 | 4 | ||
Cartilage (Min-Max: 0–31) | Tissue morphology | Fibrous tissue | Mostly fibrocartilage | Mix Hyaline cartilage and fibrocartilage | Mostly hyaline cartilage | Hyaline cartilage |
Matrix staining | None | Slight | Moderate | Normal | ||
Surface regularity | Disrupted surface | Fissuring | Horizontal lamination of surface | Smooth and intact | ||
Structure integrity | Severe disintegration | Slight break | Normal | |||
Neo-cartilage alignment with native cartilage | Depressed | Elevated | Leveled | |||
Thickness of neo-cartilage | No cartilage | 50-100 % of normal cartilage | Similar to normal | |||
Bonding to the native cartilage | Not bonded | Partially bonded at both ends or bonded at one end | Bonded at the both ends | |||
Chondrocyte clustering | 25-100 % of the cells | <25 % of cells is grouped in clusters | No clusters | |||
Hypocellularity | Severe | Moderate | Slight | Normal | ||
Cell distribution | Disorganized | Moderate disorganization | Slight disorganization | Columnar | ||
Degenerative changes in the adjacent native cartilage | Severe hypocellularity, poor or no staining | Mild or moderate hypocellularity, slight staining | Normal cellularity, mild clusters, moderate staining | Normal cellularity, no clusters, normal staining | ||
Tidemark continuity | Absent | Partial | Present | |||
Bone (Min-Max: 0–12) | Reconstruction of subchondral bone | No reconstruction | Minimal | Reduced | Normal | |
Bone infiltration into defect area | None | Partial | Complete | |||
Bonding with adjacent bone | Without continuity on either edge | Partial on both edges | Complete on one edge | Complete on both edges | ||
Subchondral bone morphology | Only fibrous tissue | Compact bone and fibrous tissue | Compact bone | Trabecular with some compact bone | Normal trabecular bone | |