Thumb tenosynovitis with hard nodules that hurt when pressed may be caused by excessive flexion and extension of the thumb, etc., which inflames the tendon sheath of the thumb, hence the pain when pressed. It is recommended to consult a doctor in time to identify the cause of the disease. If the thumb is kept in one position for a long time, such as excessive flexion and extension, then the bunion extensor and bunion extensor muscles repeatedly rub inside the tendon sheath, resulting in inflammation of the tendon sheath area. Inflammatory reactions such as redness, swelling, and warmth appear on the local skin, and a hard knot can be felt at the radial tuberosity, which will show pain when pressed. It is common in people who use their fingers for a long time, such as knitting and keyboarding. It is recommended that patients with thumb tenosynovitis with symptoms of hard knots that hurt when pressed, go to a regular hospital in time to see a doctor to clarify the cause of the disease, and then give targeted treatment.