Bending of the middle finger in the morning may be caused by soft tissue contusion, osteoarthritis, stenosing tenosynovitis, rheumatoid arthritis and so on. 1. Soft tissue contusion: If the middle finger is subjected to direct or indirect violence, it is easy to cause soft tissue contusion, local swelling and pain, causing the middle finger to bend and not straight in the morning. 2. Osteoarthritis: the bones of the human body will undergo degenerative changes with age, which may lead to soreness and pain in the joints of the middle finger during the onset of the disease, resulting in the phenomenon of the middle finger not being able to bend and stretch straight in the morning. 3. Stenosing tenosynovitis: when the middle finger is overactive for a long time and suffers from strain, stenosing tenosynovitis will be triggered, which will cause the symptom that the middle finger can’t bend and stretch straight in the morning. 4. Rheumatoid arthritis: If the condition of rheumatoid arthritis continues to progress, obvious finger joint deformities are likely to occur, causing serious restrictions on joint activities, resulting in the middle finger bending and extension in the morning. Patients who have morning middle finger bending not straight, should immediately go to the hospital, after a clear diagnosis, under the guidance of the doctor for treatment, so as not to delay the condition.