Skip to main content

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
  1. Grade = depth progression into cartilage.