Objective:To compare the mid-to long-term clinical outcomes between suture anchor and simple suture for acute injury to lateral ankle ligament (cauda equina tear near the insertion).Methods:This retrospective study included 146 patients (professional and semi-professional athletes) who had been treated for acute injury to lateral ankle ligament (cauda equina tear near the insertion) at Department of Sports Medicine, The Third Hospital Affiliated to Peking University from June 2007 to May 2017.They were 101 males and 45 females, with an age of (27.1±10.3) years (from 12 to 62 years). Depending on ligament repair techniques, the patients were divided into a suture anchor group of 81 cases subjected to reconstruction of the torn ligament with a 1.8 mm suture anchor, and a simple suture group of 65 cases subjected to direct suture of the torn ligament with a braided thread. The 2 groups were compared in terms of visual analog scale (VAS) pain scores, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scores and Tegner scores at preoperation and the last follow-up, time and level of postoperative motion recovery, proportion of limited joint motion, incidence of re-sprain and patient satisfaction.Results:There was no significant difference in the preoperative general data between the 2 groups, showing they were comparable ( P>0.05). The mean follow-up duration was (46.1±14.1) months (from 36 to 132 months). The VAS pain score, AOFAS ankle-hindfoot score and Tegner score at the last follow-up were significantly improved than those before operation in all the patients ( P<0.05). Postoperatively, there was no significant difference between the 2 groups in VAS pain score, AOFAS ankle-hindfoot score, Tegner score, incidence of re-sprain or proportion of limited joint motion ( P> 0.05). The suture anchor group was significantly better than the simple suture group in the level of postoperative motion recovery (92%±13% versus 89%±13%) and time of postoperative motion recovery [(4.2±1.1) months versus (4.6±1.0) months] ( P<0.05). Conclusions:Ligament repair, either by suture anchor or by simple suture, is a reliable procedure for patients with high sports demands after severe acute injury to the lateral ankle ligament. Compared with simple suture, suture anchor may accelerate postoperative motion recovery to the pre-injury level.