Trans-syndesmotic fixation in supination external rotation type 4 injuries: Are intraoperative tests reliable?

Background: Ankle fractures occur due to a rotational mechanism. According to the Lauge-Hansen classification, supination-external rotation (SER) injuries are the most common type. Following osseous fixation, the evaluation and treatment of syndesmotic injuries in these injuries are controversial. This study aimed to evaluate the clinical, functional, and radiological results of trans-syndesmotic fixation using intraoperative tests in SER type 4 ankle injuries.

Methods: Ankle syndesmosis was intraoperatively evaluated using cotton/hook and manual external rotation stress tests in 64 patients with SER type 4 fracture dislocation injuries. These patients were divided into two groups: those treated with and without trans-syndesmotic fixation in addition to open reduction and internal fixation of the fractures. Ankle range of motion (ROM), American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score, and Olerud-Molander Ankle Score (OMAS), tibiofibular overlap, tibiofibular clear space, and joint arthritis based on the Kellgren-Lawrence (K-L) scale were evaluated.

Results: Median values of OMAS (Z=-3.92, p<0.001), AOFAS (Z=-4.31, p<0.001), and ROM (Z=-2.95, p=0.003) were higher in Group 1. There were no differences between the groups regarding tibiofibular overlap median values (Z=-0.59, p=0.0554), tibiofibular clear space (Z=-1.13, p=0.258), and Kellgren-Lawrence arthritis scale. Lack of posterior malleolus fixation was found to increase the risk of arthritis by 18.197 times, despite having trans-syndesmotic fixation, which was statistically significant (Confidence Interval, CI: 2.482-133.417, p=0.004) (Table 4).

Conclusion: Median values of OMAS, AOFAS, and ROM in patients without trans-syndesmotic fixation were lower. These results indicate that intraoperative tests may not provide entirely accurate results in SER type 4 injuries. Failure to detect a syndesmotic injury timely can result in instability. Therefore, we think that routine trans-syndesmotic fixation, as well as posterior malleolus fixation in SER type 4 ankle injuries, may improve outcomes.