Table 2 Modified O’Driscoll histological and histochemical grading scale
| Â | Score |
|---|---|
Nature of the predominant tissue | Â |
Cellular morphology | Â |
  Hyaline articular cartilage | 4 |
  Incompletely differentiated mesenchyme | 2 |
  Fibrous tissue or bone | 0 |
Safranin-O staining of the matrix | Â |
  Normal or nearly normal | 3 |
  Moderate | 2 |
  Slight | 1 |
  None | 0 |
Structural characteristics | Â |
Surface regularity | Â |
  Smooth and intact | 3 |
  Superficial horizontal lamination | 2 |
  Fissures - 25 to 100% of the thickness | 1 |
  Severe disruption, including fibrillation | 0 |
Structural integrity | Â |
  Normal | 2 |
  Slight disruption, including cysts | 1 |
  Severe disintegration | 0 |
Thickness | Â |
  100% of normal adjacent cartilage | 2 |
  50 to 100% of normal cartilage | 1 |
  0 to 50% of normal cartilage | 0 |
Bonding to the adjacent cartilage | Â |
  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 | Â |
Hypocellularity | Â |
  Normal cellularity | 3 |
  Slightly hypocellularity | 2 |
  Moderate hypocellularity | 1 |
  Severe hypocellularity | 0 |
Chondrocyte clustering | Â |
  No clusters | 2 |
  <25% of the cells | 1 |
  25 to 100% of the cells | 0 |
Freedom from degenerative changes in adjacent cartilage | Â |
 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 |