The pain when bending the middle finger may be caused by trauma, degenerative arthritis and stenosing tenosynovitis. 1. Trauma: If the middle finger suffers from trauma, resulting in damage to ligaments, tendons and joints, causing damage to the local nerves, it is easy to have limited finger extension, usually accompanied by pain symptoms. 2. Degenerative arthritis: Degenerative arthritis is usually associated with significant degenerative damage to the cartilage of the joints of the middle finger or reactive hyperplasia of the subchondral bone, due to the hyperplasia of the bone pressure on the ligaments around the joints and the joints, resulting in pain in the flexion of the finger. 3. Stenosing tenosynovitis: stenosing tenosynovitis is usually associated with more activities of the wrist and fingers, and the main symptom is localized pain and activity restriction, so there will be the symptom that the middle finger can not be flexed and it hurts when it is bent. The middle finger can not bend a bend pain may also be caused by other reasons, specific need to go to the regular hospital, a clear diagnosis, follow the doctor’s instructions for treatment.