Joint pain in one digit can be caused by tenosynovitis, rheumatoid arthritis, carpal tunnel syndrome, and other causes such as trauma. 1. Tendovaginitis: Tendovaginitis may be related to chronic strain and is a sterile inflammatory disease. Patients will have symptoms such as elastic fingers, pressure pain, limited joint movement, joint swelling, and joint pain if the patient develops tenosynovitis in one finger. 2. Rheumatoid arthritis: Rheumatoid arthritis may be caused by heredity, autoimmune function abnormality and so on. Patients will have pain in the proximal interphalangeal joints of the fingers and metacarpophalangeal joints, accompanied by morning stiffness, fever, weight loss and other manifestations, and some of the patients will have pain in the joints of one finger. 3. Carpal tunnel syndrome: Carpal tunnel syndrome may be caused by exogenous compression and small lumen of carpal tunnel. The patient will manifest as pain or numbness in the demonstrative finger, middle finger and thumb, thus the patient will manifest as pain in one digit joint. 4. Other: patients with one finger joint pain may also be due to finger trauma, osteoarthritis and other diseases. It is recommended that patients with one finger joint pain need to consult a doctor in a timely manner, you can choose the appropriate measures for treatment under the guidance of the doctor.