There are three main reasons for pain in the middle finger of the left hand: the first is due to trauma to the position of the middle finger of the left hand, or lifting and carrying heavy objects, resulting in soft tissue injuries and localized bruising, as well as inflammatory edema, which irritates the surrounding peripheral nerves and causes pain. Especially when continuing finger joint activities, it will stimulate the injured tissues, resulting in more pronounced pain. The second situation is due to frequent flexion and extension activities in the finger area, resulting in continuous soft tissue fatigue, and gradually form strain injury, especially when accompanied by cold, will lead to increased local inflammation buildup, irritation aggravation and lead to more obvious pain. The third situation is often due to tenosynovitis, which is due to frequent finger flexion and extension activities, resulting in increased friction between the tendon and the tendon sheath, and the gradual formation of inflammatory hyperplasia, which will lead to obvious pain in the finger when performing flexion and extension activities.