The inability to bend the thumb may be due to the following reasons: first, contracture of the palmar tendon membrane. If the contracture of the palmar tendon membrane is serious, it will affect the movement of the fingers, resulting in the inability to flex and straighten the finger joints, which should be investigated and treated with early release surgery after diagnosis. Second, stenosing tenosynovitis of the thumb, when there is a serious stenosing tenosynovitis of the thumb, the thumb can appear the symptoms of the card, serious cases can not be flexed, often in the straight position, then to carry out early consultation, diagnosis, if necessary, surgery. Third, tendon injury, when the flexor tendon is damaged, it can also make the thumb can not be flexed, then the relevant examination should be carried out for diagnosis.