Background: The aim of this study was to determine the functional and radiological outcomes of arthroscopic treatment of anterior ankle impingement (AAI) in patients with chronic lateral ankle instability (CAI). Methods: All patients with CAI between June 2012 and May 2015 were invited to participate in this investigation. All of them accepted open modified Brostrom repair of lateral ankle ligaments and were divided into two groups: AAI group (with anterior ankle impingement) and pure CAI group (without anterior ankle impingement). All of them were followed up using American Orthopaedic Foot and Ankle Society Score (AOFAS), Karlsson Ankle Functional Score and Tegner activity score. Ankle dorsiflexion was also examined. X-ray examination was applied to investigate anterior tibiotalar osteophytes. Results: Finally, a total of 60 patients were followed up at a mean of 37 +/- 10 months, including 22 patients in the AAI group and 38 patients in the pure CAI group. Preoperatively, the AAI group had significant lower AOFAS score (62.9 +/- 11.7 vs 72.9 +/- 11.1; p = 0.002) and Tegner activity score (1.5 +/- 0.8 vs 2.1 +/- 1.0; p = 0.04) respectively when compared with the pure CAI group. The ankle dorsiflexion of the AAI group (13 +/- 2.1) was also significantly lower than that of the pure CAI group (26.2 +/- 2.1) (p = 0.001). However, there was no significant difference in the AOFAS score or the Karlsson score or the Tegner score or the Ankle dorsiflexion between the two groups postoperatively. The postoperative X-ray images demonstrated complete osteophyte resection in all patients, and no recurrence of osteophyte. Conclusion: The functional outcome scores and dorsiflexion had significantly improved postoperatively. Combined treatment of chronic ankle instability and anterior ankle impingement produced satisfactory surgical outcomes in patients with CAI accompanied by anterior ankle impingement symptom.