Hi everyone, my name is Rohan Bhimani and I'm going to talk about arthroscopic assessment of syndesmotic instability. Are we pulling correctly in coronal plane? So disclosure, this study was supported by a grant from Anna. Our other disclosures can be found on the Academy website. So syndesmotic instability is a three-dimensional problem with resulting instability manifesting in coronal, sagittal, and translational plane. Currently arthroscopic evaluation of the syndesmotic joint is considered as a gold standard with coronal plane assessment using the lateral hook test has been shown to be an effective technique. Previous study by Stoffel and his colleague assessed syndesmotic instability using fluoroscopy and they concluded that 100 newton of laterally directed force was required to assess syndesmotic instability. However, there are a couple of questions that still remain unclear. One, what is the impact of angulation of POE on the coronal plane measurements while assessing syndesmotic joint? And two, what is the minimum amount of force required to assess such instability when looked at arthroscopically? So the aims of our study was one, to determine the amount of displacement variation that occurs when lateral force is angled anteriorly or posteriorly, two, to determine the optimal amount of force needed to assess syndesmotic instability using a lateral hook test when looked at arthroscopically. Our hypothesis was different directions of force application would generate different degrees of diastasis and syndesmosis. So moving on to the methods, it was a cadaveric study in which we included 10 fresh frozen above knee cadavers. We measured the anterior and posterior coronal space measurements at anterior one-third and the posterior one-third of the tibial incisora arthroscopically. So we first performed a measurement in an intact state, and then after transsectioning of the anterior inferior tibiofibular ligament and the interosseous ligament. In all scenarios, lateral hook test was performed under increasing force from zero to 120 newtons with increasing force of 20 newtons. Lateral hook test was first performed in neutral position, that is zero degree of angulation, then anterior inclination of 15 degrees, and followed by posterior inclination of 15 degrees. So these are our experimental set of images where you can see an image A, where the lateral hook test is performed in zero degrees of angulation, B, anterior inclination of 15 degrees, C, where we have performed a test in 15 degrees of posterior angulation. Image D shows we've used a calibrated ball-tip probes to measure the coronal space where the ball probe size increases by 0.1 millimeters. So moving on to our results, we found that anterior third coronal space measurement increases with increase in laterally directed force in an intact state. However, after transsectioning of the AITFL and IOL, there was an increase in lateral diastasis with increase in laterally directed force up to 60 newtons, followed by a plateau. Moreover, we also found that the posterior directed force afforded a larger diastasis compared to neutral or anterior directed pull. Similar results were also seen for the posterior third coronal space measurements, with increasing force resulting in increasing diastasis for intact state, and 60 newton being the threshold to differentiate stable from an unstable syndesmosis. So these are the graphical representation of our measurements, where you can see on the left are the measurements from the anterior third incisor coronal space measurements and the posterior third on your right. The lines on the bottom are the measurements obtained from intact state, and the lines on the top are from the measurements obtained after transsectioning of the AITFL and IOL. And you can see the highest line is for the measurement performed when the hook was directed posteriorly. So moving on to our discussion and conclusion, so accurate diagnosis of syndesmotic instability is essential for good clinical outcome and preventing long-term morbidity. A study found a force of 60 newton was the threshold to distinguish between stable and unstable syndesmotic joint. Moreover, posterior directed pull afforded the larger absolute coronal space measurements, with anterior coronal space measurement increasing by 0.3 millimeters and posterior space increasing by 0.2 millimeters when subjected to posterior directed force. These numbers become increasingly important as instability becomes more and more subtle. However, further studies are recommended to determine the applicability of these findings in diagnosis and management of syndesmotic instability. Thank you.

arthroscopic assessment

syndesmotic instability

coronal plane measurements

lateral hook test

cadaveric study