Sudden inability to straighten the right demonstrative finger may be related to tenosynovitis, injury to the flexor tendon of the finger, mallet finger deformity, and may be given non-surgical and surgical treatments. 1. Tenosynovitis: mainly refers to excessive finger or wrist activities, and the finger is bent and cannot be straightened. Non-surgical treatments such as reducing local activities, hot compresses, diclofenac sodium cream application, and closed treatment can be given. Repeated episodes and non-surgical treatment is ineffective can be given to surgical treatment. 2. Finger flexor tendon injury: from the finger to the metacarpophalangeal joint of the little finger, the interphalangeal joint is in the form of semi-flexion, and the angle of flexion is gradually increasing, and the tip of each finger is pointing to the navicular tuberosity of the wrist. Tendon suture can be given as treatment. 3. Mallet finger deformity: the little finger is the most common, and the end joints of the fingers may be drooping and flexed. It can be treated with splinting and surgery. Suddenly the right hand finger is not straight may also be other causes, it is recommended to go to the regular hospital to do a comprehensive and detailed examination, to clarify the cause of the disease, to give standardized treatment. Diclofenac sodium cream is a prescription drug, should be taken under the diagnostic guidance of a doctor, not self-medication.