Does Proximal-Distal Tibial Tunnel Placement for PCL Reconstruction Matter?

Abstract

The purpose of this study was to investigate the biomechanical effects of proximal-distal tibial tunnel placement on posterior laxity in PCL reconstruction. Eighteen human cadaveric knees were studied, consisting of nine matched pairs. Transtibial PCL reconstruction was performed using a simulated arthroscopic technique. The native PCL was resected, and Achilles tendon autografts were used for PCL reconstruction. The specimens were divided into two groups based on tibial tunnel placement: 1) anatomic tunnel and 2) non-anatomic tunnel. The anatomic tibial tunnel was placed at the footprint of the PCL, 1 cm distal to the joint line, while the non-anatomic tibial tunnel was placed more proximal to this, at the joint line. A 150-N cyclic posterior tibial load was applied using a Materials Testing System (MTS) machine at 0⁰, 30⁰, 60⁰, and 90⁰ of knee flexion. In 10 specimens, a static 250-N posterior tibial load was applied at 90⁰ of knee flexion. Posterior tibial translation in the sagittal plane was recorded. A Mann-Whitney U test was used to compare posterior tibial translation between the two groups. Statistical significance was set defined as p <0.05. With application of a 150-N posteriorly directed cyclic force, the anatomic tunnel group demonstrated significantly less posterior tibial translation than the non-anatomic tunnel group at 0⁰, 30⁰, 60⁰, and 90⁰ of knee flexion (p <0.05). The anatomic tunnel group also demonstrated significantly less posterior tibial translation than the non-anatomic tunnel group at 90⁰ with a static 250-N posteriorly directed force applied (p <0.05). Anatomic distal tibial tunnel placement recreating the tibial origin of the PCL provided significantly greater restraint to posterior tibial translation than proximal non-anatomic tunnel placement. We recommend careful placement of an anatomic distal tibial tunnel during PCL reconstruction for avoidance of posterior laxity.