Outline 1. Grading systems for osteochondral damage
Outerbridge System

Grade I: 	Softening and swelling of cartilage

Grade II: 	Fragmentation and fissuring, less than
                0.5-in diameter

Grade III:	Fragmentation and fissuring, greater
                than 0.5-in diameter

Grade IV:	Erosion of cartilage down to exposed
                subchondral bone

Noyes System

Grade 1:	Cartilage surface intact (1A = some
                remaining resilience; 1B = deformation)

Grade 2A: 	Cartilage surface damaged (cracks,
                fibrillation, fissuring, or fragmentation); with
                less than half of cartilage thickness involved

Grade 2B: 	Depth of involvement greater than half of
                cartilage thickness but without exposed bone

Grade 3: 	Bone exposed (3A = surface intact;
                3B = surface cavitation)
Beaty, JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL. American Academy of Orthopaedic Surgeons. 1999 Ch. 42, pp. 533-557.