Table 2.

Histological scoring system for (A) overall tissue evaluation, (B) subchondral bone evaluation, and (C) cartilage evaluation in rabbit osteochondral defects [17].

	Score
(a) Overall defect evaluation (throughout the entire defect depth)
1. Percent filling with newly formed tissue
100%	3
>50%	2
<50%	1
0%	0
2. Percent degradation of the implant
100%	3
>50%	2
<50%	1
0%	0
(b) Subchondral bone evaluation (within the bottom 2 mm of defect)
3. Percent filling with newly formed tissue
100%	3
>50%	2
<50%	1
0%	0
4. Subchondral bone morphology
Normal, trabecular bone	4
Trabecular bone, with some compact bone	3
Compact bone	2
Compact bone and fibrous tissue	1
Only fibrous tissue or no tissue	0
5. Extent of new tissue bonding with adjacent bone
Complete on both edges	3
Complete on one edge	2
Partial on both edges	1
Without continuity on either edge	0
(C) Cartilage evaluation (within the upper 1 mm of defect)
6. Morphology of newly formed surface tissue
Exclusively articular cartilage	4
Mainly hyaline cartilage	3
Fibrocartilage (spherical morphology observed with ≥ 75% of cells)	2
Only fibrous cartilage (spherical morphology observed with < 75% of cells)	1
No tissue	0
7.Thickness of newly formed cartilage
Similar to the surrounding cartilage	3
Greater than the surrounding cartilage	2
Less than the surrounding cartilage	1
No cartilage	0
8. Joint surface regularity
Smooth, intact surface	3
Surface fissures (<25% of new surface thickness)	2
Deep fissures (≥25% of new surface thickness)	1
Complete disruption of the new surface	0