Grade IV arthritis is arthritic destruction of the joint cartilage to the point of exposure of the underlying bone.

Outerbridge Grade IV - patellar cartilage fibrillated with exposure of underlying bone in the tibia

Grade IV damage


Grading versus pain

Although it looks as if it should always be painful, and it generally is, there are nonetheless many patients with Grade IV cartilage damage who do not experience pain.



Non-operative management of osteoarthritis of the knee joint Vaishya R, Pariyo GB, Agarwal AK and Vijay V. J Clin Orthop Trauma. 2016 Jul-Sep; 7(3): 170–176.

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