Typical results for normal and moderately damaged osteoarthritic cartilage (Mankin’s grade 4–6). col: collagen; signal intensity: +++: very strong; ++: strong; +: weak; −: none; matrix integrity (histological): n: normal; f: fibrillated; e: eroded). The different zones (surface, upper/lower middle, deep) are distinguished by criteria such as cell shape, matrix appearance, and distance to the subchondral bone and the tide mark
| Cartilage layer | Normal cartilage (Mankin’s grade 0–2) | Osteoarthritic cartilage (Mankin’s grade 4–6) | |||||||
| Matrix integrity | PG content | Aggrecan expression | Phenotypic markers | Matrix integrity | PG content | Aggrecan expression | Phenotypic markers | ||
| Superficial | n | −/+ | −/+ | − | e | ||||
| Middle | |||||||||
| Upper | n | ++ | ++ | − | f | − | − | − | |
| Lower | n | ++ | ++ | − | (f) | ++ | +++ | −/col-III | |
| Deep | |||||||||
| Upper | n | ++ | ++ | − | n | ++ | +++ | − | |
| Lower | n | ++ | ++ | − | n | ++ | +++ | col-X | |
| Calcified | n | + | −/+ | col-X | n | + | −/+ | col-X | |