Objective:To compare the efficacy of arthroscopic all-inside ligament repair with suture augmentation and ligament reconstruction with tendons in the treatment of chronic ankle instability with poor remnant quality of the anterior talofibular ligament (ATFL) tissue.Methods:A retrospective cohort study was conducted to analyze the clinical data of 37 patients with chronic ankle instability treated at Huashan Hospital Affiliated to Fudan University from January 2018 to August 2020, including 34 males (34 ankles) and 3 females (3 ankles); aged 18-57 years [(32.2±7.2)years]. The time from injury to operation ranged from 3-360 months [48(12, 120)months]. All patients underwent arthroscopic all-inside ankle stabilization surgery, of which 19 underwent ligament repair with suture augmentation (augmented repair group) and 18 underwent traditional ligament reconstruction with allograft/autograft tendons (tendon reconstruction group). The degree of ATFL injury and intra-articular lesions (osteophytes, loose bodies and cartilage damage) were recorded during the operation. The Karlsson scale and Tegner scale were evaluated before operation and at the last follow-up. The number of patients who were able to complete partial weight-bearing/return to normal walking/return to sports postoperatively and the time required were compared between the two groups. Postoperative complications were observed.Results:All patients were followed up for 12-32 months [21(16, 28)months]. There were no significant differences in the degree of ATFL injury and intra-articular lesions (osteophytes, loose bodies and cartilage damage) seen during the operation between the two groups (all P>0.05). At the last follow-up, the Karlsson score in augmented repair group and tendon reconstruction group [95.0(90.0, 98.5)points and 95.0(87.8, 99.3)points] was significantly higher than the preoperative level [65.0(51.0, 75.0)points and 65.0(53.3, 78.0)points] (all P<0.01). At the last follow-up, the Tegner score in augmented repair group and tendon reconstruction group [5.0(3.5, 6.0)points and 5.0(3.3, 6.0)points] were significantly higher than the preoperative level [3.0(2.0, 4.0)points and 2.5(1.3, 4.0)points] (all P<0.01). There were no significant differences in Karlsson score and Tegner score between the two groups (all P>0.05). All patients completed partial weight-bearing after 3.0(2.0, 4.0)weeks in augmented repair group and 4.0(3.5, 6.0)weeks in tendon reconstruction group. All patients returned to normal walking after 8.0(6.0, 9.0)weeks in augmented repair group and 8.0(5.5, 12.0)weeks in tendon reconstruction group. A total of 13 patients (63%) in augmented repair group and 13 patients (72%) in tendon reconstruction group successfully returned to sports postoperatively and the time required was 6.0(3.5, 8.0) months and 6.0(4.5, 12.0)months, respectively. There were no significant differences in the above indicators between the two groups (all P>0.05), but augmented repair group had a trend of faster completion of partial weight-bearing than tendon reconstruction group. There was 1 patient [5%(1/19)] in augmented repair group and 1 patient [6%(1/18)] in tendon reconstruction group who reported feelings of instability during exercise postoperatively ( P>0.05). None of the patients in augmented repair group had limited ankle range-of-motion, not different from 1 patient [6%(1/18)] in tendon reconstruction group ( P>0.05). Conclusion:In the treatment of chronic ankle instability with poor remnant quality of the anterior talofibular ligament (ATFL) tissue, both arthroscopic all-inside ligament repair with suture augmentation and ligament reconstruction with tendons can improve the short-term postoperative ankle function and activity level of the patients, and the former one has advantages such as simple operative procedures and none use of grafts.