Aim and background: Ligamentous Lisfranc injuries are challenging to detect, with 20–40% of them remaining undiagnosed or misdiagnosed at initial presentation. While direct visualization in the operation room is the gold standard for detecting Lisfranc instability, it is also the most invasive. Other techniques currently available for assessment are unstandardized and nonreproducible. We aimed to introduce a novel reproducible intraoperative mechanical testing method (Listract test) for isolated Lisfranc instability assessment. Technique: The Lisfranc ligament between the first cuneiform (C1) and second metatarsus (M2) in eight lower leg cadaveric specimens was dissected to replicate C1-M2 Lisfranc instability. Intraoperative radiographs were used for measuring C1-M2 diastasis and area in two states, “stable” and “unstable.” A 50N distraction force was applied in the direction of the C1-M2 ligament through two K-wires for “unstable” conditions. Three methods of fixation—flexible fixation, metal screw, and bio-integrative screw were alternatively used to stabilize the joint, and the Listract test was applied again in a “stable” condition. Receiver operating characteristic (ROC) analysis for the Listract test was performed using Statistical Package for the Social Sciences (SPSS). The sensitivity and specificity of the Listract test for detection of ruptured ligament instability using C1-M2 diastasis (cutoff taken as 3 mm) were 100 and 77.8%. Similarly, the instability of ruptured ligament measured using C1-M2 area (cutoff taken as 26.1 mm) was 85 and 100%. The intraclass correlation coefficient (ICC) for C1-M2 diastasis and area measurements was 0.84 and 0.92, respectively. Conclusion and clinical significance: The Listract test is a simple, standardizable, and replicable intraoperative method for evaluating the Lisfranc joint for instability. Developing a device with this mechanism can be clinically significant to accurately assess the severity of instability intraoperatively and provide appropriate treatment.