The symptoms of tenosynovitis of the left thumb are twofold, the first, limited function or even dysfunction of the left thumb. The second, significant pain in the left thumb, resulting in localized redness, swelling, heat, and pain. Tenosynovitis of the thumb occurs because of the frequent flexion and extension activities of the thumb, which leads to significant friction between the tendon and the tendon sheath, and eventually leads to aseptic edema of the tendon, which is followed by significant puffing and finally significant restriction or even dysfunction in the flexion and extension of the thumb. Another obvious symptom is the pain and swelling of the thumb.