There are a number of causes of finger joint coarctation. It may be caused by trauma, rheumatoid arthritis, bone tumor, and other factors such as degenerative joint changes. 1. Trauma: trauma is the main factor leading to large finger joints, when the finger is injured by external force resulting in joint fracture or dislocation, the finger will be deformed and swollen, and if the healing after trauma is not good, it will also lead to joint deformation. 2. Rheumatoid arthritis: rheumatoid arthritis can also cause deformation and enlargement of finger joints, often accompanied by obvious morning stiffness, usually manifested as stiffness of the fingers after waking up in the morning, with limited activities, lasting more than one hour. 3. Bone tumors: Bone tumors occurring in the finger joints may lead to bone destruction, resulting in joint deformation, pain and swelling. It needs to be identified by imaging (e.g. X-ray, CT, MRI, etc.) and other tests. 4. Others: In addition, for people who have been using hand labor for a long time or middle-aged and old people, due to degenerative joints, joint strain, osteophytes in fingers, etc., it can lead to deformation and coarseness of finger joints, which can also be accompanied by clinical symptoms such as pain and limitation of activities, and can be clearly diagnosed through X-ray examination. There are many reasons for the enlargement of finger joints, and it is recommended that patients actively seek medical treatment to avoid delaying their condition.