Objective To summarize the short-term effectiveness of the surgical treatment for grade III pronation-external rotation ankle fractures. Methods Between October 2011 and May 2015, 36 patients with pronation-external rotation ankle fractures (grade III) were treated with internal fixation and repair of the anterior lower tibiofibular ligament, including 21 males and 15 females with an average age of 45.2 years (range, 21-72 years). Injury was caused by sprain in 19 cases, by traffic accident in 6 cases, and by falling from height in 11 cases. All patients had closed fractures, with no blood vessel and nerve injury. The locations were the left ankle in 13 cases and the right ankle in 23 cases. The time from injury to operation was 3 to 10 days (mean, 6.5 days). At last follow-up, ankle function was evaluated by American Orthopaedic Foot and Ankle Society (AOFAS) ankle-foot score, and the improvement of pain was evaluated by visual analogue scale (VAS). Results Primary healing of incision was obtained in all patients, no incision infection and skin necrosis occurred. Twenty-eight patients were followed up 12-36 months (mean, 17.5 months). X-ray films showed bone union was achieved within 2.6-5 months (mean, 3.2 months). No fracture of internal fixation and disruption of tibiofibular diastasis occurred. At last follow-up, according to AOFAS score for ankle function evaluation, the pain score was 36.3±2.9, the function score was 44.3±3.2, the ligament condition score was 9.2±0.5, and the total score was 89.8±6.6; the results were excellent in 11 cases, good in 15 cases, and fair in 2 cases. VAS score was 1.6±0.5. The range of motion of the ankle was (13±5)° in dorsiflexion and (38±9)° in planteroflexion. Conclusion Repair of anterior tibial ligament is an effective method to treat tibiofibular diastasis injury in the surgical treatment of grade III pronation-external rotation ankle fractures, with convenient operation, and satisfactory short-term effectiveness.