The purpose of this retrospective study was to determine long-term functional outcomes and device tolerance achieved in adult patients who chose to undergo an extraosseous talotarsal stabilization procedure HyProCure®® for the treatment of flexible talotarsal joint deformity. Eighty-three adult patients participated in this study. Postoperative subjective assessment of device performance was evaluated using Maryland Foot Scores, which were collected at a mean follow-up period of 51 months. The mean postoperative Maryland Foot Score was 88 out of 100; postoperatively, 52% of cases reported complete alleviation of foot pain, 69% of cases had no limitations on their foot functional abilities, and 80% of cases reported complete satisfaction with the appearance of their feet. The implant was removed in 7 out of 117 cases (removal rate: 6%) due to prolonged pain of the anterior talofibular ligament (4 cases), psychogenic reaction (2 cases), and postoperative infection (1 case). The long-term positive subjective outcomes and excellent patient satisfaction obtained in this study may imply that extraosseous talotarsal stabilization was effective in stabilizing the talotarsal joint complex and eliminating excessive abnormal pronation, thus reducing pain and improving quality of life of the patients; it represents a possible treatment option for partial talotarsal dislocation in cases with flexible and reducible deformity.