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Table 2 The modified O’Driscoll histologic score

From: Full-thickness cartilage defects are repaired via a microfracture technique and intraarticular injection of the small-molecule compound kartogenin

Characteristic Grading
I. % Hyaline cartilage 80–100 Score
  60–80 8
  40–60 6
  20–40 4
  0–20 2
II. Structural characteristics   0
A. Surface irregularity Smooth and intact  
  Fissures 2
  Severe disruption, fibrillation 1
B. Structural integrity Normal 0
  Slight disruption, including cysts 2
  Severe lack of integration 1
C. Thickness 100% of normal adjacent cartilage 0
  50% to 100% or thicker than normal 2
  0–50% 1
D. Bonding to adjacent cartilage Bonded at both ends of graft 0
  Bonded at one end/partially both ends 2
  Not bonded 1
III. Freedom from cellular changes of degeneration Normal cellularity, no clusters 0
  Slight hypocellularity, <25% chondrocyte clusters 2
  Moderate hypocellularity, >25% clusters 1
IV. Freedom from degenerate changes in adjacent cartilage Normal cellularity, no clusters, normal staining 0
  Normal cellularity, mild clusters, moderate staining 3
  Mild or mod hypocellularity, slight staining 2
  Severe hypocellularity, slight staining 1
V. Reconstitution of subchondral bone Complete reconstitution 0
  Greater than 50% recon 2
  50% or less recon 1
VI. Bonding of repair cartilage to de novo subchondral bone Complete and uninterrupted 0
  <100% but >50% recon 2
  <50% complete 1
VII. Safrinin O staining >80% homogeneous positive stain 0
  40%–80% homogeneous positive stain 2
  <40% homogeneous positive stain 1
  Total score 0
   Max27