Determination of the Optimal Syndesmosis Fixation Angle Using the Mortise View of the Ankle Joint

Background: Syndesmosis is an important soft-tissue component supporting ankle stability. It is commonly injured along with ankle fractures. Accurate reduction and fixation of syndesmosis is essential to obtain better functional results. Therefore, we aimed to find a practical method using the mortise view of the ankle to determine the optimal syndesmosis fixation angle intraoperatively. Methods: We randomly selected 200 adults (100 women and 100 men) aged 18 to 60 years. Three-dimensional anatomical models of the tibia and fibula were created. We created a best-fit plane on the articular surface of the medial malleolus and a 90° vertical plane to the medial malleolus plane. We determined two splines on the cortical borders of the tibia and fibula distant from the most superior point of the ankle joint in horizontal view. We created two spheres that fit to the predefined splines. The optimal syndesmosis fixation angle was determined measuring the angle between the line connecting the center points of the spheres and the 90° vertical plane to the medial malleolus plane. Results: We observed no statistically significant difference in optimal syndesmosis fixation angles between sex groups. The participant mean ± SD age was 47.1 ± 10.5 years. The optimal syndesmosis fixation angle in the mortise view was found to be 21° ± 4.3°. Conclusions: We determined the optimal syndesmosis fixation angle to be 21° ± 4.3° using the mortise view of the ankle. The surgeon could evaluate the whole articular surface of the ankle joint with the medial and lateral syndesmotic spaces in mortise view accurately, and at the same position syndesmosis fixation could be performed at a mean ± SD angle of 21° ± 4.3°. © 2023, American Podiatric Medical Association. All rights reserved.