Bending stiffness of the middle finger of the left hand may be related to physiological factors such as exposure to cold and fatigue, and may be caused by tenosynovitis, rheumatoid arthritis, osteoarthritis, trauma and other diseases, which should be treated and dealt with according to different etiological factors. 1. Cold and fatigue: after cold and fatigue, the ligaments and muscles of the middle finger joints will be overly stretched, and there will be stiffness when bending, which can be improved and relieved by resting and keeping warm. 2. Tenosynovitis: the main thing is to take sufficient rest, avoid excessive manual labor, can be hot compresses, massage, baking lamp irradiation, if there is obvious pain, you can take oral ibuprofen extended-release capsules, celecoxib tablets and other non-steroidal pain relievers, serious can take local closure or tenosynovial release surgical treatment. 3. Rheumatoid arthritis: pay more attention to keep warm, free from cold, so that the finger full rest, can choose methotrexate, leflunomide and other anti-rheumatic drugs, but also can choose acupuncture, ultrashort wave irradiation lamp for adjuvant therapy. 4. Osteoarthritis: to reduce finger activities, such as joint stiffness and swelling is obvious, you can wear a brace, oral glucosamine capsules, ibuprofen extended-release capsules and other drugs for treatment. 5. Trauma: you can carry out local physiotherapy and hot compresses (cold compresses in the acute stage), appropriate joint function exercise of the fingers to avoid joint dysfunction. To sum up, when the left middle finger joint bends and stiffens, if it is difficult to relieve, you should consult a doctor in time, according to the cause of the disease by a professional doctor, to formulate an individualized treatment plan, do not blindly use drugs.