The optimal tibial tunnel placement to maximize the graft bending angle in the transtibial posterior cruciate ligament reconstruction: a quantitative assessment in three-dimensional computed tomography model

Abstract

Background The graft bending angle created by the graft and the tibial tunnel has inevitably occurred during the transtibial posterior cruciate ligament (PCL) reconstruction. However, few studies quantitively analyzed this angle. This study aimed to (I) explore the optimal tibial tunnel placement to maximize the graft bending angle in the PCL reconstruction; (II) reveal the effect of the tibial tunnel placement on the graft bending angle. Methods This was an in-vitro surgical simulation study based on the three-dimensional (3D) computed tomography (CT). A total of 55 patients who took CT scanning for knee injuries were selected (April 2020 to January 2022) from the local hospital database for review. The 3D knee models were established on the Mimics software based on the knees’ CT data. Using the Rhinoceros software to simulate the transtibial PCL reconstruction on the 3D CT knee model. The anteromedial and anterolateral tibial tunnel approaches were simulated with different tibial tunnel angle. The graft bending angle and tibial tunnel length (TTL) with different tibial tunnel angles were quantitively analyzed. Results The graft bending angle in anterolateral approach with a 50° tibial tunnel angle was significantly greater than it in anteromedial approach with a 60° tibial tunnel angle (P<0.001). There was no difference of the graft bending angle between the anterolateral approach with a 40° tibial tunnel angle and the anteromedial approach with a 60° tibial tunnel angle (P>0.05). The graft bending angle showed a strong correlation with the tibial tunnel angle (for anteromedial approach: r=0.759, P<0.001; for anterolateral approach: r=0.702, P<0.001). The best-fit equation to calculate the graft bending angle based on the tibial tunnel angle was Y = 0.89*X + 59.05 in anteromedial tibial tunnel approach (r 2 =0.576), and was Y = 0.78*X + 80.21 anterolateral tibial tunnel approach (r 2 =0.493). Conclusions The graft bending angle and TTL will significantly increase as the tibial tunnel angle becomes greater. Maximizing the tibial tunnel angle (50° tibial tunnel angle) in the anterolateral approach could provide the greatest graft bending angle in the PCL reconstruction. No matter how the tibial tunnel angle is changed in the anteromedial approach, using anterolateral approach might reduce the killer turn effect more effectively than using anteromedial approach.

An in-vitro three-dimensional surgical simulation technique to predict tibial tunnel length in transtibial posterior cruciate ligament reconstruction

“…Therefore, the outcomes need to be validated by future clinical or cadaveric studies. Previous studies have demonstrated that 3D knee joint models can be used for precise quantitative analysis and exhibit excellent measurement accuracy and reliability [ 22 ]. Therefore, the results of this study can facilitate surgeons in better preoperative planning and intraoperative estimation of TTL.…”

The tibial capsular reflection and septum in posterior compartment are safe and reliable soft‐tissue landmark for tibial tunnel drilling in posterior cruciate ligament reconstruction

“…Although the posterior cruciate ligament reconstruction (PCLR) technique has evolved considerably over recent decades [1,14,15], there is still no consensus regarding the optimal surgical approach for PCLR [6,11], including whether to perform single-bundle or doublebundle reconstruction [20], whether to perform transtibial or tibial inlays and the positioning of the tunnel. Currently, there are many possible reasons for the failure of PCLR surgery [21], one of which is incorrect bone tunnel placement [24], particularly positioning of the tibial bone tunnel, which is considered to be very important in PCLR [8,18].…”