There may be several reasons for a finger not being straight: first, rupture of the extensor tendon, especially when the extensor tendon of the finger is ruptured at the most distal end of the finger, the finger may not be straight, which should be diagnosed with medical history and related investigations, and early surgical suture treatment should be performed after diagnosis. Secondly, stenosing tenosynovitis, if stenosing tenosynovitis is serious, the flexor tendon can be stuck, which leads to finger extension, then the diagnosis and treatment should be carried out. Third, palmar tendon membrane contracture, palmar tendon membrane contracture can also appear finger extension phenomenon, this time to carry out the relevant investigation for diagnosis and treatment.