Thank you, Dr. Lee and Dr. Mateva, it's an honor to be here. A big shout out to my co-authors, I could not have done the work without their help. These are our disclosures, here we go. Increased posterior tibial slope we have found leads to increased forces on our ACL grafts, which ultimately leads to increased graft failure rates. Treatment options for patients with an unfavorable posterior tibial slope and an ACL deficient knee include slope correcting osteotomy and soft tissue procedures such as lateral extra articular tenodesis. Our purpose was to determine if a tibial slope threshold exists where LAT no longer affects ACL graft forces, tibial translation, and internal rotation of the tibia. We also wanted to better understand the clinical setting for LAT adding to an ACL reconstruction. We hypothesize that LAT in addition to ACL reconstruction will decrease ACL graft forces, decrease tibial motion as the tibial slope increases to unfavorable posterior tibial slopes throughout knee range of motion compared to ACL reconstruction alone. We took 12 fresh frozen cadaveric knees without arthritis or meniscal damage and performed an ACL reconstruction with a soft tissue bovine xenograft for improvement of standardization. Our LAT was performed via the modify the mare technique, as you can see here, and redirected under the FCL. All specimens were tested on an Instrom simulating a slow land. Graft force, anterior tibial translation, internal rotation were all measured via graft transducer, laser, and Instrom itself, respectively, at three flexion angles and at four posterior slopes. What did we see? We saw that an increase in posterior tibial slope leads to increase in graft force in a linear fashion through all flexion angles for both ACL reconstruction and with the addition of LAT. This is consistent with what we know in the literature as increased posterior tibial slope increases graft force, but we saw that in the setting of ACL reconstruction with and without an LAT. For anterior tibial translation, we also saw an increase with increased posterior tibial slope in a linear fashion at all flexion angles and in all states. This is also consistent with what we know in the literature, but this is, once again, in the setting of these procedures. So what about when we compare ACL reconstruction with and without an LAT? Well, we know from the AJSM article in 2020 that an LAT addition leads to decreased graft force and decreased anterior tibial translation, but this did not take into consideration posterior tibial slopes, whether favorable or unfavorable. Well, a lot of information came out of our study. The most notable finding was that at 30 degrees of flexion, adding an LAT decreased graft force by about 8.3%, and this was the case for favorable and unfavorable posterior tibial slopes. While 30 degrees is not all flexion angles, 30 degrees is a very important position of the knee, as it is the athletic stance for most athletic events, as you can see here. And yet when we look at slope reduction or the effect of a bony correction on graft force, we see even higher decreases in graft force, upwards of two times that seen with the soft tissue procedure. And when we look at common clinical osteotomies, we see that this number encroaches 30 to 50%. In terms of anterior tibial translation, we saw that the LAT restrained anterior tibial motion more than the intact state by about two and a half millimeters. While this rose concern for over-constraint, we only saw this at zero degrees in extension and not throughout all flexion angles. No other statistical significant difference was seen between ACLR with and without an LAT. So in conclusion, this is the first study to show the interaction of both LAT and posterior tibial slope in regards to ACL reconstruction and graft forces and tibial motion. So when we look back at our original purpose, we did not find a posterior tibial slope threshold to limit the effects of LAT, but in fact saw these protective effects throughout all posterior tibial slopes. But we did learn more about the clinical indication for ACL reconstruction with LAT, however, we're still seeing that a bony correction is still outweighing the soft tissue procedures. So the take-home point, an LAT does provide a greater than 8% reduction in graft force, but this is not as strong of a reduction compared to posterior tibial slope correction. And so these findings weigh into the risk and benefit discussion for our patients. And while we still have a lot to learn about the knee biomechanics and the associated procedures, there may be a role for a less risky soft tissue procedure to correct and offset a bony correction. Thank you for your time and opportunity to be here.

posterior tibial slope

ACL graft forces

lateral extra-articular tenodesis

ACL reconstruction

cadaveric knees