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Radiographic hallmarks of osteoahritis: Joint space narrowing, Osteophytes, Subchondral cysts, Bony sclerosis (eburnation) Kellgren & Lawrence staging: Grade 0 Normal Grade 1 Minimal osteophyte Normal joint space Grade 2 Definite osteophyte Possible joint space narrowing Grade 3 Definite osteophyte Definite joint space narrowing Grade 4 Large osteophytes, Marked joint-space narrowing, Sclerosis, Deformity OA is common in first CMC of thumb, DIP, PIP, knee, hip joint and spine. Osteophytes that form at DIP joints are known as Heberden nodes. At PIP joint, such osteophytes are known as Bouchard nodes. Ref: Maheshwari 6e pg 295.