Good morning, everyone. Thank you for having me here. My name is Yantrasit Panich. I have nothing to disclose. For leaf fang injury, an annual incident rate of 9.2 per 100,000 people was recently reported. This rate is five-fold higher than previously estimated. More than two-thirds of these injuries are caused by low energy trauma, which tend to be distinctly characterized by a primarily ligamental leaf fang injury with poximal variant pattern of instability. Bilateral weight-bearing radial grafts are widely accepted as the standard to diagnose instability by contralateral comparison, but greater than 2 mm difference in widening indicates instability. However, CT imaging is not obfuscated by metatarsal overlapping and could provide better visualization of bony structure. This study aimed to model a purely ligamentous leaf fang injury to determine widening between the C1 and M2 after each ligament dissection under non-weight, partial weight, and full weight-bearing condition, evaluated by weight-bearing CT. For the method, 12 pairs of two-knee cadavers were inside dorsally to visualize the leaf fang ligamentous conflict between C1 and M2. An intact ligament condition was the control of group 1. Relay was sequentially dissected dorsal group 2, interosseous group 3, and plantar ligament for group 4. Then, in group 5, we equally randomized each pair into three groups, group 5A redissect the first TMT capsule, group 5B redissect the second TMT capsule, and group 5C redissect the interosseous Q9-formed ligament. Next, for group 6, the remaining intact ligaments were similarly randomized for transsection. Finally, in group 7, all ligaments were dissected. CT scans were taken for three weight-bearing conditions after that, and the distance between the lateral border of C1 and the medial border of M2 at the center of the interosseous leaf fang ligament was measured to evaluate the diagnosis for both coronal and axial wounds. We used ANOVA to determine the significant difference between out-group and dependent T-test for weight-bearing variables. For the result, in group 1, with intact ligaments, at area C1, M2, distance was 4 mm for axial and 3.9 mm for coronal imaging. There is no statistically significant difference between pair feed or for any weight-bearing conditions. In group 4, after dissect, the interosseous and plantar ligament widening of 1.5 and 2 mm were observed for partial and full weight-bearing in axial view, and also 1.4 and 1.8 mm for partial and full weight-bearing in coronal view. I would like to draw your attention to the application of our standard radiographic criteria of 2 mm. For non-weight-bearing conditions, we could observe that widening in group 6 that include inter-Q9 form ligament and group 7 in both planes. For partial weight-bearing conditions, we start to see that widening in the majority of the specimen in group 5C only in the axial view, and for full weight-bearing conditions, we start to see that widening in group 5C in both views. For the effect of weight-bearing on the distance comparing to non-weight-bearing conditions, partial weight-bearing the distance increased on average about 16-19% and 22-26% for full weight-bearing. This graph shows the estimated mean of C1, M2 distance on axial view of each condition. The widest distance has been observed in group 7, and mostly the distance after full weight-bearing demonstrates the case head value within each group. We could see the similar trend in the coronal parameter. For the discussion, our findings suggest that the selection of the different ligamentous complex including dorsal inter-rotate and plantar ligament was insufficient to depict evidence of instability using the aforementioned criteria. In the most of specimens, justly 8% in partial weight-bearing and 29% in full weight-bearing reached that criteria. Moreover, our study identified an external rotation displacement of the M2 using a 3D model analysis after inter-rotation disjoint ligament dissection under various weight-bearing conditions. In example, external rotation displacement about 6.7 degrees was observed in group 3 under partial weight-bearing conditions as the picture on the right side. With an evolution in technology, 3D model analysis might gain more attention to achieve a true understanding of displacement after ligament injury actually in foot and ankle. We found consistent pattern of external rotation of M2, so widening between the superior portion of the joint between C1 and M2 might be the earliest sign of significant after significant ligament injury, but further study are still needed. We have several strengths of this study. The first, this study is a well-conducted catalytic study illustrating all required information for quality appraisal for cadaveric study. Second, with a large magnitude of variation in the anatomy of plantar ligament, we use a medial approach to confirm a complete dissection. The third, our CT parameters demonstrate a good reliance in trying to observe reliability. However, there are some limitations. Our results are based on a small number of specimen cadaveric model lack of normal physical resilience that might affect the distance. We use 40 and 80 kilograms from mean weight of the included cadaver. However, whether a patient could actually bear this much weight after an acute ligament injury is not known. Conclusion, we are bearing CT scan can improve the ability to detect purely ligamentous ligament injury by comparing C1 and M2 distance to the uninjured site. The widening exceeding one millimeter more than the normal contralateral site for partial weight-bearing condition could clinically indicate least frank ligamentous complex injury. Thank you for your attention.

leaf fang injuries

weight-bearing CT scans

ligament widening

cadaver knees

ligamentous complex injury