 Hi, I'm Dr. Sunil Kini working as a concert and orthopedic surgeon at Manipal Hospital's Bangalore. The cause of pain in arthritis mainly depends on the condition or the pathology we are dealing with. For example, if you're talking about osteoarthritis, which is age-related, it is mainly related to the wear of the cartilage, which causes pain. We classify it as grade 1 to 4, grade 1 wherein starts from diminishing of joint space to grade 4, what we call bone-on-bone, where the pain becomes severe and it can often be continuous. In other conditions such as rheumatoid arthritis or inflammatory conditions, the pain actually is because of the inflammation of the layers of the joint, which we call as synovium. In other conditions such as gouty arthritis, the pain is often due to deposition of crystals in the joint, which we also call to as gouty arthritis.