Objective: To investigate the mid-to-long-term efficacy of patients with chronic ankle instability combined with posterior impingement syndrome after 3-9 years of follow-up, and to analyze the influencing factors.Methods: From February 2010 to December 2015, 46 patients underwent concurrent lateral ankle ligament repair with posterior ankle arthroscopic surgery at the Institute of Sports Medicine, Peking University Third Hospital. The patient was first placed in a prone position and underwent arthroscopic debridement for the posterior impingement. After finishing the posterior arthroscopy, the surgeon and assistants first translated the patient to the affected side, then turned to the healthy side, and changed the position to the supine position. During the turning over, another assistant held the arthroscope and the instrument to ensure that it was sterile and could be used without replacement. The anterior ankle arthroscopy was operated if necessary and the lateral ankle ligament repair was anatomic repaired with anchors. The 42 patients were followed up, including 26 males and 16 females. The average age was (28.9±10.0) years. The patient’s clinical symptoms, joint stability, mobility and motor function were compared by questionnaire and physical examination. The preoperative and postoperative visual analogue scale (VAS) scores, American Orthopaedic Foot and Ankle Society (AOFAS) scores, Tegner scores were compared, and the clinical scores and the patient age, gender, height and weight were compared. The correlations between body mass index (BMI), preoperative duration, surgery duration, and cartilage injury were analyzed. Results: The mean follow-up time was (71.8±22.8) months. The postoperative VAS scores (1.0 vs. 5.0, P<0.001), AOFAS scores (92 vs. 80, P<0.001), and Tegner scores (6.5 vs. 2, P<0.001) were significantly superior to the preoperative levels. The excellent and good rate was 97.6%. The postoperative VAS score (t=2.719, P=0.10), AOFAS score (t=-2.853, P=0.10), Tegner score (t=-3.443, P=0.001) and time to return exercise (t=2.814, P=0.008) were negatively correlated with the patient age, and the postoperative VAS score was negatively correlated with cartilage injury (Z=-2.195, P=0.028).Conclusion: The mid-to-long-term clinical outcomes of the chronic ankle ligament instability combined with the posterior impingement were good. The age of the patients was negatively correlated with the clinical outcome. The combined cartilage injury could aggravate the postoperative pain.