BACKGROUND: Assessment of intraoperative syndemsotic instability remains a controversial topic. To date, no study has directly compared 5 available methods. MATERIALS AND METHODS: The purpose of the present study was to assess the reliability of five stress assessment methods (Cotton Hook, External Rotation, Arthroscopic, Direct Palpation, and Direct Visualization) across various syndesmotic injury conditions (ventral disruption, 2-ligament injury, and 3-ligament injury) in an in-vitro model. It was hypothesized that the Cotton Hook (CHT) and External Rotation (ER) methods would be the least reliable. A cadaveric model of syndesmotic injury was employed in eight through the knee specimens and assessments were performed. RESULTS: Overall, direct visualization was most reliable for discerning syndesmotic disruption, irrespective of the injury condition (p = 0.01). Arthroscopic assessment was reliable in 2 and 3-ligament injury conditions (p <
0.05)
while Cotton Hook and External Rotation were reliable in 3-ligament injuries (p = 0.01, p = 0.04). Arthoscopic, Cotton Hook, and External Rotation assessment(s) were unreliable for discerning isolated ventral disruption (anterior inferior tibiofibular ligament). CONCLUSIONS: In the present cadaveric model, direct visualization of the anterolateral articular surface of the ankle was the most reliable method for discerning syndesmotic injury. Discontinuity of the articular surface between the anterolateral tibia and anteromedial fibula was readily identified in all injury conditions. Surgeons should be cognizant of the inherent subjectivity, and limited reliability of historically popularized syndesmotic stress assessment methods. LEVEL OF EVIDENCE: Level V, cadaveric.