Causes of bone protrusion at the middle finger joints are more reasons, need to be analyzed in specific cases: First, physiological reasons, due to the existence of physiological differences, the size of different people’s joints are different, so it can cause the bone protrusion at the joints of the middle finger of some people, which is a physiological difference, and can be left unprocessed. Second, pathological causes, mainly because of certain joint diseases caused by bone lesions, causing bone surface protrusion, such as rheumatoid arthritis, osteoarthritis, psoriatic arthritis, etc., at this time need to be in the physician’s guidance, to complete the joint X-rays, ultrasound joints, nuclear magnetic and the necessary hematology examination, to look for the possible causes, if you determine to be caused by a certain disease, for the treatment of the disease can be.