The tibial tunnel location would be lateral easiler by placing the tunnel under-the-ACL During transtibial Posterior Cruciate Ligament Reconstruction with remnant preservation

Abstract

Abstract Background：An accurate method for precise tibial tunnel preparation and preserving remnant are believed as the key technologies of transtibial PCL reconstruction. However, there are technically difficult when creating an accurate tibial tunnel under good visualization without removing the remnant PCL fibers. We found tibial guide could through the path under-the-ACL(between the ACL and lateral femoral condyle) to posterolateral compartment at 45° Knee flexion and varus stress, while tibial guide tip can locate the insertion from the lateral of PCL and get around the PCL remnant and ACL fibers; placing tunnel inferolaterally and preserving remnant intactly will be easily at the same time . Purpose : (1) report a modified technique for tibial tunnel preparation to place the tunnel at inferolateral position easily without remnant’s block in PCL reconstruction with remnant preservation. (2) compare tibial tunnel placement of two guide path by in vivo 3-dimensional computed tomography（3D-CT）:the path under-the-ACL（the guide insertion we recommend）and the path over-the-ACL（the guide insertion we used to）. Methods： Tibial tunnel aperture location was analyzed by postoperative in vivo CT in 50 patients who underwent single-bundle remnant-preserving PCL reconstruction ,22 by over-the-ACL and 28 by under-the-ACL tibial guide insertion techniques by a retrospective study from 2016 to 2020 to our center. Tibial tunnel positions were measured in the medial to lateral and proximal to distal directions of the posterior proximal tibia. Stress radiography of pre- and post-operation were used to evaluate the knee stability. Results：All patients were follow-up above 24 months. In the medial to lateral direction, the center of tibial tunnel aperture was located more laterally in the under-the-ACL group of (0.51±0.01)% than over-the-ACL group of (0.46±0.04)%（P＜0.05）. The tibial tunnel position in the proximal to distal direction, determined by absolute value and relative percentage, were similar in the 2 groups. Two groups were significantly improved the posterior laxity control compared with preoperation by stress radiography at 24 months postoperatively, and posterior tibial translation (4.00±1.03)mm in A group compared with (5.43±1.09)mm in B group（P＜0.05）. Conclusions: Tibial tunnel apertures would be located more laterally after under-the-ACL tibial guide insertion than after over-the-ACL tibial guide insertion. There was, however, no significant difference between these techniques in distance from the joint line to the tibial tunnel aperture. Insertion under-the-ACL to the PCL stump may result in better placement of the PCL in Fanelli area.