Table 2 OA cartilage histopathology grade assessment; grading methodology
From: Jellyfish mucin may have potential disease-modifying effects on osteoarthritis
Grade (key feature) | Associated criteria (tissue reaction |
|---|---|
Grade 1: surface intact | Matrix: superficial zone intact, oedema and/or superficial fibrillation (abrasion), focal superficial matrix condensation Cells: death, proliferation (clusters), hypertrophy, superficial zone Reaction must be more than superficial fibrillation only |
Grade 2: surface discontinuity | As above + Matrix discontinuity at superficial zone (deep fibrillation) ± Cationic stain matrix depletion (Safranin O or Toluidine Blue) upper 1/3 of cartilage ± Focal perichondronal increased stain (mid zone) ± Disorientation of chondron columns Cells: death, proliferation (clusters), hypertrophy |
Grade 3: vertical fissures (clefts) | As above Matrix vertical fissures into mid zone, branched fissures ± Cationic stain depletion (Safranin O or Toluidine Blue) into lower 2/3 of cartilage (deep zone) ± New collagen formation (polarized light microscopy, Picro Sirius Red stain) Cells: death, regeneration (clusters), hypertrophy, cartilage domains adjacent to fissures |
Grade 4: erosion | Cartilage matrix loss: delamination of superficial layer, mid layer cyst formation Excavation: matrix loss superficial layer and mid zone |
Grade 5: denudation | Surface: sclerotic bone or reparative tissue including fibrocartilage within denuded surface. Microfracture with repair limited to bone surface |
Grade 6: deformation | Bone remodelling (more than osteophyte formation only). Includes: microfracturewith fibrocartilaginous and osseous repair extending above the previous surface |