Objective:To investigate the early outcome of endoscopy-assisted percutaneous non-fusion fixation of unilateral C 1 lateral mass screw and C 2 pedicle screw in treatment of type II odontoid fracture in elderly patients. Methods:A retrospective case series study was conducted to analyze clinical data of 12 elderly patients with type II odontoid fracture admitted to Second Affiliated Hospital of Chongqing Medical University from July 2016 to September 2018. There were 5 males and 7 females, aged 66-89 years [(75.2±6.7)years]. American Society of Anesthesiologists (ASA) scores for all patients were greater than 2 points. Ten patients were classified to Grade E and the other two were classified to Grade D by American Spinal Injury Association (ASIA) scale scores. All patients underwent endoscopy-assisted percutaneous non-fusion fixation of unilateral C 1 lateral mass screw and C 2 pedicle screw. The operation time, intraoperative blood loss, hospital stays, intraoperative and postoperative complications were collected. The Neck Disability Index (NDI) scores and ASIA scale scores were compared preoperatively and 6 weeks postoperatively. The visual analogue scales (VAS) were recorded preoperatively, 6 weeks, 3, 6, 9 and 12 months postoperatively. Fracture healing was followed up postoperatively. Results:Operation time was 98-169 minutes [(123.2±17.7)minutes]. Intraoperative blood loss was 20-40 ml [(30.0±7.1)ml]. Hospital stays were 6-9 days [(7.3±0.7)days]. No neurovascular injury was observed intraoperatively and postoperatively. The NDI were 8%-30%[(19.3±6.3)%] 6 weeks postoperatively, significantly lower than 19%-45%[(33.1±9.9)%] preoperatively( P<0.05). All patients' ASIA scale scores reached grade E postoperatively. The VAS constantly decreased from 6-9 points [(7.8±0.9)points] preoperatively to 1-3 points [(1.8±0.6)points] 12 months postoperatively ( P<0.05). All the patients achieved bone healing after 4-11 months [(7.3±2.1)months]. Conclusion:For type II odontoid fracture in elderly patients, endoscopy-assisted percutaneous unilateral atlantoaxial screw non-fusion fixation can relieve pain and achieve rapid recovery of neck function and bone healing.