I am grateful for the invitation to share this academic podium with you. In the next few minutes, I will present a biomechanical approach to the different options for ACL reconstruction. In the recent years, orthopedics worldwide have focused on modifying our ACL reconstruction technique with the objective of positioning ourselves the ACL femoral anatomic point according to the studies conducted by Dr. Freddie Foon. To this end, we have corrected the angle of inclination of our graft with respect to the tibial surface platoon. However, a consensus has not yet been reached on the exact position point of our femoral tunnel as seen in this study from 2021. Additionally, importance has also been given to the tibial footprint and the position of the tunnel reconstruction. The school of Dr. Freddie Foon designed the anti-remedial technique, also called the anatomic technique, which allows the better femoral access but gives an ample freedom for the location of the tunnel tibial. This leads to non-linear tunnel design as opposite to the classic trans-tibial technique which is general linear designs. Given the difference, we tested the hypothesis that reconstruction the ACL with non-linear tunnel morphology affects the biomechanical characteristics of the tendon graft. There are some studies that support our hypothesis and show that non-linear tunnel designs present higher stress in the extreme bending and extension. To test this hypothesis, we designed a comparative study between some biomechanical characteristics of the anti-remedial technique and modified trans-tibial technique with an inclination of 55 degrees, which allows reaching the femoral point as described by Dr. Yasuda in 2010. The variables we analyzed were, first, the resulting force vector, which acts in every moment and is determined using the Kosyma of angle by distance of the graft. The second, the maximum resistance prior to the fall, which functions under extreme demand situation and was calculated using the mechanical work formula, multiplying the force vector by the pre-stabilized values of resistance of each tissue of the graft. For this experiment, we formed two groups with 25 patients each, group one with anti-remedial technique and group two with modified trans-tibial technique, who underwent uncomplicated ACL reconstruction surgery under the same conditions in the hospital where we work. First, we determined our ideal value to reach with respect to the native ligament, which in the result force was almost 44 points. In the anti-remedial technique, we found three functional vectors, tibial, articular, and femoral, which gave us a resulting vector of 37 points, while in the modified trans-tibial technique, it was a single vector with a value of 40 points. This showed that the linear vector generating modified trans-tibial technique has value closer than native ligament. When we evaluate the maximum resistance prior to the fall, we found that our native ACL parameters value was 9,515. When we evaluate in both study groups, we found that values varied according to the graft used. In anti-remedial technique, the hamstring surpassed 157%. The patellar tendon graft by 114%, and the quads tendon graft only reached 83%. In modified trans-tibial technique, the hamstring surpassed 208%, patellar tendon 151%, and quads tendon graft only reached 99%. After the result of this experiment, we can consider that there are biomechanical alteration in non-linear design of graft tunnels in ACL, and non-linear tunnel design increased the risk of graft failure. Here are some results for our clinical experience. We performed ACL reconstruction with the technique on 78 patients, football players, and followed them up for three years. We found functional scalp volumes similar to the traditional techniques, had no complication, and had a 91% return to the sport rate. We know that our study design has a theoretical framework of physical analysis, where there may be more variables that influence the behavior of graft in ACL reconstruction, such as implant type, patient age, bone density, among others. We consider that these variables could complement this study in biomechanical cadaveric laboratory. With this work, we only want to provide a biomechanical analytical contribution of two surgical techniques and their possible limitation. Thank you for your attention.

biomechanical approach

ACL reconstruction

anti-remedial technique

non-linear tunnel design

graft failure