To evaluate the efficacy of a modified procedure for internal fixation of closed hammer fingers with a kerfing needle. Methods In this group, 22 cases, including 5 cases of the index finger, 4 cases of the middle finger, 5 cases of the ring finger, and 8 cases of the little finger, were fixed with a modified internal fixation of the keratoplasty needle. The results of all the patients were taken X-ray after surgery. 22 cases of hammer finger were well reset and fixed, with reference to the evaluation standard of total flexion of each finger joint (TAM), excellent: TAM is the same as the healthy side; good: TAM>75% of the healthy side; acceptable: TAM>50% of the healthy side; poor: TAM<50% of the healthy side. Among the 22 cases in this group: excellent: 15 cases, good: 5 cases, acceptable: 2 cases, poor: 0 cases, with an excellent rate of 91%. Conclusion: Internal fixation of hammer finger with a modified surgical technique using a kerf pin is a simple and effective surgical procedure. Key words: closed hammer finger, Clinique needle, modified procedure Our department has treated 22 cases of closed hammer finger with modified procedure of Clinique needle internal fixation from February 2007 to May 2010, and achieved satisfactory results. 1. Clinical data 1.1 General data: There were 22 cases in this group, 14 males and 8 females, aged 13-53 years old, with an average of 28 years old. Among them, 10 cases were playing ball impact injuries, 7 cases were living injuries, and 5 cases were machine injuries. Among them, there were 5 cases of index finger, 4 cases of middle finger, 5 cases of ring finger and 8 cases of little finger, and the patients had distal interphalangeal joint flexion deformity after the injury. The time from injury to surgery ranged from 1 h to 10 d, with an average of 1.8 days, and the operative time was 5-15 min, with an average of 10 min. Preoperative routine radiographs were taken, and two of the cases had small end-joint avulsion fractures (not exceeding 1/3 of the articular surface) 1.2 Surgical method: Under nerve block anesthesia at the root of the finger, the distal interphalangeal joint was straightened, and a 1-mm diameter Kirschner needle was used to drill from the tip of the finger to the base of the middle phalanx, with C arm fluoroscopy, the Kirschner needle was well positioned, the tail of the Kirschner needle was cut, the distal phalanx was broken into an over-extended position with both hands, the over-extension angle was 15-30° C-arm fluoroscopy of the lateral position of the finger, the Kirschner needle was slightly bent toward the palmar side, and the tail of the needle was bent and hooked and left outside the skin. 1.3 Results: Postoperative radiographs were taken in all patients. 22 hammer fingers were well repositioned and fixed with 10-15° of distal interphalangeal joint hyperextension. The kerf pins were removed six weeks after surgery, and none of the cases had kerf pin breakage, slippage, or pinhole infection. At postoperative follow-up from 3 months to 2 years, with an average of 6 months, the fingers were normal in appearance, without joint pain or stiffness. Referring to the evaluation standard of total flexion of each finger joint (TAM) [1], excellent: TAM was the same as the healthy side; good: TAM > 75% of the healthy side; acceptable: TAM > 50% of the healthy side; poor: TAM < 50% of the healthy side. Among the 22 cases in this group: excellent: 15 cases, good: 5 cases, acceptable: 2 cases, poor: 0 cases, the excellent rate reached 91%. 2, Discussion: Hammer finger is due to the rupture of the extensor tendon between the base of the terminal phalanx dorsal to the central tendon bundle stop (i.e., tendon hammer finger or soft tissue hammer finger) and the avulsion of part of the phalanx tendon (i.e., bony hammer finger). The conservative treatment method used for hammer finger, plaster or splint fixation, is too loose to play a fixed role, and too tight will affect the blood supply, compress the skin, and cause breakage and infection. In our group, we used a modified procedure of hammer finger fixation with kerf pins to achieve satisfactory results. Compared with the traditional procedure, the advantages are as follows: (1) In the traditional procedure, the needle is inserted in the distal interphalangeal joint in the hyperextension position, and it is not easy to pass the needle through the joint to the base of the proximal middle phalanx, but in the modified procedure, the needle is inserted in the distal interphalangeal joint in the extension position, so that it is easier for the needle to reach the base of the middle phalanx, and then it is made to hyperextend by external force. (2) Letting the penetrating Kirschner needle bend dorsally creates enough tension so that the angle of dorsal extension of the distal interphalangeal joint is not easily lost. Internal fixation of the hammer finger with a modified surgical procedure using a Kirschner pin is a simple and effective surgical procedure that is worth promoting in primary hospitals.