Swelling of the patient’s right middle finger can be caused by several reasons: First, trauma: If there is old trauma to the middle finger, resulting in damage to the soft tissue ligaments around the middle finger joint, swelling around the middle finger joint can occur. This is diagnosed based on the history of trauma, as well as X-rays and MRIs. Second, tenosynovitis: can lead to swelling and painful symptoms in the metacarpophalangeal joint of the middle finger. Third, gout or rheumatism, rheumatoid: can be accompanied by pain in multiple joints, as well as wandering pain. Fourth, osteoarthritis: osteoarthritis is a degenerative manifestation that can lead to swelling, pain, and deformity of the finger, which should be diagnosed and treated with relevant x-ray examinations and physical examination.