arthritis grades

what is grade 3 arthritis?
grade 0, no visible abnormality, grade 1 redness, mild swelling of wrist or up to three inflamed digits, grade 2, more than three digits swollen or redness and mild swelling of the ankle or wrist; grade 3, severe ankle and wrist inflammation; grade 4, extensive ankle and wrist inflammation including all digits, or the formation of new bone with reduced movement
