Objective To investigate the clinical efficacy of posterior screw-rod single vertebra internal fixation for anterior atlas arch displaced fracture.Methods A retrospective case series study was conducted to analyze the clinical data of 13 patients with anterior atlas arch displaced fracture admitted to Henan Provincial People's Hospital from January 2010 to March 2016.There were eight males and five females,aged 28-62 years[(40,0±9.2)years].According to Frankel grading,there was one patient with grade C and 12 patients with grade D.All patients were treated with posterior cohesive reduction with screw-rod system.Operation time,blood loss,intraoperative and postoperative complications were recorded.The operation time,intraoperative blood loss,internal fixation position,fracture healing and bone graft fusion were recorded.The Japanese orthopedic- association(JOA)score,visual analogue scale(VAS),Frankel grade,and cervical motion range were compared before and at the last follow-up.The intraoperative and postoperative complications were recorded.Results All patients were followed up for 29～68 months[(48.2±14.5)months].The operation time was 50-75 minutes[(59.5±6.5)minutes],and blood loss was 55-80 ml[(62.5±8.3)ml].After operation,fracture lines were well reset,nerve compression was relieved,pillow neck pain was alleviated,and limb function was significantly improved.CT scans confirmed bony union in al 1 patients 6 months after operation.The JOA score at the last follow-up[(15.4±0.7)points]was significantly higher than that before operation[(7.9±1.3)points](P< 0.05).The preoperative VAS was significantly decreased from(6.2±0.9)points to(1.9±1.0)points at the last follow-up(P< 0.05).The range of motion of cervical spine was close to the normal level with 70°-91°[(80.7±7.0)°]of anteflexion and extension,131°-157°[(142.9±9.1)°]of horizontal rotation,and 78°-89°[(83.8±3.2)°]of lateral flexion.One patient with incision infection and five neck stiffness as well as limited neck movement were reported,but all were cured or improved significantly after symptomatic treatment.No internal fixation lossening or breakage was found.Conclusions Posterior screw-rod single vertebra internal fixation for anterior atlas arch displaced fracture has the advantages of shortened operation time,less bleeding,less complication,good reduction as well as restored motor function of atlantoaxial joint.