Table 1 Key feature of different grades based on the Osteoarthritis Research Society International scoring system
Grade | Key feature | Associated criteria (tissue reaction) |
|---|---|---|
Zero | Surface intact, cartilage morphology intact | Matrix: normal architecture Cells: intact, appropriate orientation |
One | Surface intact | Matrix: superficial zone intact, edema and/or superficial fibrillation (abrasion) Cells: death, proliferation (clusters), hypertrophy |
Two | Surface discontinuity | Matrix: discontinuity at superficial zone Cells: death, proliferation (clusters), hypertrophy |
Three | Vertical fissures (clefts) | Matrix: vertical fissures into the mid zone Cells: death, regeneration (clusters), hypertrophy |
Four | Erosion | Matrix: matrix loss of superficial layer and mid zone |
Five | Denudation | Surface: sclerotic bone or reparative tissue including fibrocartilage within the denuded surface. Microfracture with repair limited to the bone surface |
Six | Deformation | Bone remodeling more than osteophyte formation only |