Background: While gravity-assisted ankle stress AP (GAASA) images have proven effective in evaluating deep deltoid ligament injuries, their efficacy in assessing syndesmosis injuries remains unclear. We aimed to investigate the diagnostic performance of GAASA images in detecting syndesmosis injuries. Methods: This study reviewed records of patients aged 16+ with unilateral ankle fractures in a single-center ER from 2022 to 2023. Three orthopedic surgeons evaluated standard AP and lateral X-rays, ankle mortise, and GAASA and bilateral ankle CT images in blinded sessions for syndesmosis injuries. Evaluations were repeated to assess the inter- and intra-rater reliability. Results: A total of 121 patients with suspected syndesmosis injuries were included in this study. The average age of the patients was 49.9 ± 16.6 years. Syndesmosis injuries were present in 32.2% of cases. The inter-observer reliability was the highest for GAASA images (κ = 0.701) and mortise radiographs (κ = 0.735), and lowest for CT images (κ = 0.426). GAASA images had a sensitivity of 82% and specificity of 68%. Mortise images had 55% sensitivity and 81% specificity. GAASA images showed better discriminatory power for syndesmosis injuries compared to mortise and CT images. Conclusions: GAASA images demonstrated superior sensitivity and better negative predictive values in detecting syndesmosis injuries compared to mortise radiographs and CT images. While GAASA may serve as a useful adjunct for evaluating syndesmosis injuries, its interpretation requires careful clinical correlation, and it should not be considered a replacement for standard imaging in all cases. GAASA may be of particular value in emergency or resource-limited settings where CT is not readily available, offering a practical option for ruling out injury in many patients.