·From June 2018 to November 2018, 43 patients with anterior disc displacement without reduction were selected from the Department of Oral Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. TMJ disc reposition and fixation was performed to them all. For unilateral patients, a Chinese embedded nail was used to reduce the articular disc. For bilateral patients, a Chinese embedded anchoring nail was used on the right side and a traditional anchoring nail was used on the left side. Clinical and magnetic resonance imaging (MRI) examination were performed before surgery, 1 month after surgery, 6 months after surgery and 1 year after surgery. Clinical evaluation indexes included maximum interincisal opening (MIO) and TMJ pain score. The disc position, disc length and condylar height were measured by MRI, by using three-circle method. Repetitive measnre analysis of variance was used for statistical analysis of preoperative and postoperative MIO, visual analog scale (VAS) score for TMJ pain, disc length and condyle height.

·Thirty-one patients with fifty-three joints finished all follow-up periods. The success rates of Chinese embedded anchoring nail and traditional anchoring nail were 90.3% and 90.9%, respectively. One year after surgery, the patients' jaw motion improved significantly. The MIO increased from (34.65±8.63) mm before surgery to (42.84±7.46) mm 1 year after surgery (P=0.000). The pain was significantly alleviated, and the VAS score for TMJ pain decreased from (2.94±1.13) before surgery to (0.39±0.55) 1 year after surgery (P=0.000). Postoperative MRI examination result showed increased disc length. The condyle height did not change significantly 6 months after surgery (P>0.05), but it increased by an average of 1.54 mm 1 year after surgery (P=0.002). None of the 31 joints with the Chinese embeded anchorage nail had foreign body sensation, while of the 22 joints with the traditional anchorage nail, 7 patients could feel the protrusion in front of the tragus, and 2 of them had obvious foreign body sensation.

·Improved Chinese embedded TMJ anchoring nail has similar success rate and less foreign body sensation than traditional anchoring nail. TMJ disc repositioning and fixation is beneficial to improve joint function and relieve pain. New bone can be detected 1 year after surgery.