The left hand slight fracture 40 days will be painful to consider local adhesion, fracture displacement, soft tissue injury has not yet recovered, poor fracture healing, too much activity and so on. 1. Local adhesion: left hand slight fracture 40 days will be painful pain may be a long time after the fracture of the brake, resulting in local muscle, tendon and soft tissue adhesion, there will be finger flexion and extension activities are limited, if the fracture healing can be manipulated to release, joint pain can gradually disappear, joint mobility to improve. 2. Fracture displacement: finger fracture 40 days will be painful may also be due to the fracture has been displaced to stimulate the surrounding tissues, need to go to the hospital to take a look at the film, if there is a significant displacement needs to be manipulated to reset, finger splints fixed. 3. Soft tissue injury: soft tissue injury if there is no good recovery, there is still local swelling and pain. 4. Poor fracture healing: generally 40 days fracture has not grown well, there will be local pain. 5. Too much activity: if too much activity, it will cause local muscle fatigue or fracture stimulation of the surrounding tissue causing pain. So finger fracture 40 days will be painful need to go to the hospital for further examination, to clarify the specific causes of pain and treatment.