Table 2.
The modified O'Driscoll histology score.
| Category | Score |
|---|---|
| Nature of predominant tissue | |
| Cell morphology | |
| Hyaline 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 |
| Fissure 25–100% of the thickness | 1 |
| Severe disruption | 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 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 | 3 |
| Slight | 2 |
| Moderate | 1 |
| Severe | 0 |
| Chondrocyte clustering | |
| No clusters | 2 |
| <25% of the cells | 1 |
| 25–100% of the cells | 0 |
| Freedom from degeneration changes in adjacent cartilage | |
| Normal cellularity, no clusters, normal staining | 3 |
| Normal cellularity, mild clusters, moderate staining | 2 |
| Mild or moderate hypocellularity, slight staining | 1 |
| Severe hypocellularity, poor or no staining | 0 |