Predisposing factors for chronic syndesmotic instability following syndesmotic fixation in ankle fracture: Minimum 5-year follow-up outcomes

•The chronic syndesmotic instability rate was 20.5% after syndesmotic fixation at least five years of midterm follow up.•Obesity and concomitant posterior malleolar fracture were significant risk factors for postoperative syndesmotic instability at minimum five years of follow up.•The mean clinical scores in the syndesmotic instability group were significantly lower than those in the no syndesmotic instability group.•Surgeons should be aware that patients with obesity and posterior malleolus fractures are more likely to develop chronic syndesmosis instability, and that accurate reduction and more stable fixation should be considered.