Two-Bundle Posterior Cruciate Ligament Reconstruction

Abstract

This study had two purposes: first, to determine how femoral attachment location affects the load sharing between the two bundles of a Y-type posterior cruciate ligament reconstruction, and second, to determine how the bundles, separately and in combination, control posterior tibial translation throughout the full range of knee flexion. One and two-bundle reconstructions were performed in 12 cadaveric knees. The one-bundle reconstructions were attached within the femoral posterior cruciate ligament footprint at one of three locations, high and shallow (S1), mid and shallow (S2), or mid and deep (D). The two-bundle reconstructions comprised an S1 bundle with either an S2 or a D bundle. Posterior translation and bundle tension were measured as the knee was flexed from full extension to 1,200 of flexion while a posterior force of either 50 or 100 N was applied to the proximal tibia. The shallow one-bundle reconstruction restored posterior translation to within 2 mm of that of the intact knee over the entire range of knee flexion. The deep reconstruction did not control abnormal posterior translation above 45 degrees. The tension in the shallow bundles increased with knee flexion, and the deep bundle tension remained nearly constant throughout knee flexion. Both two-bundle reconstructions controlled posterior translation, but with different load-sharing characteristics. The S1-S2 configuration resisted posterior tibial translation as both bundles became taut in flexion. In contrast, the S1-D configuration resisted posterior translation in a reciprocal fashion with the D bundle tension being the greatest in extension and the S1 bundle tension being the greatest tension in flexion.

Posterior Cruciate Ligament: Focus on Conflicting Issues

“…The influence of the femoral attachment site, as well as the number of bundles, was further evaluated 1,2,7). In a study using variable femoral attachment sites, Mannor et al7) reported that a shallow femoral insertion allows for better control of posterior translation.…”

“…In a study using variable femoral attachment sites, Mannor et al7) reported that a shallow femoral insertion allows for better control of posterior translation. However, they could not prove the possibility of graft elongation resulting from high graft tension.…”

Medial Femoral Condyle Strength After Tunnel Placement for Single- and Double-Bundle Posterior Cruciate Ligament Reconstruction

“…17,18 Posterior cruciate ligament reconstruction is thus being studied in greater detail, and biomechanical evaluations of various techniques are being reported. 6,9,11,13 Biomechanical studies have demonstrated that single-bundle reconstructions of the anterolateral bundle can restore normal posterior lax-ity at low level knee fl exion angles, 2,5,12 but double-bundle reconstructions are needed to more closely mimic normal knee kinematics. 6,9,11,13 Unlike anterior cruciate ligament (ACL) reconstruction, PCL reconstruction requires drilling through the medial femoral condyle, which may be a problem with double-bundle reconstruction.…”

Anatomy of the Femoral Footprint of the Posterior Cruciate Ligament: A Systematic Review

“…4,7 Recent biomechanical studies suggest that the 2 bundles of the PCL may have a co-dominant relation, functioning in a synergistic fashion throughout the range of motion. 8 Injuries to the PCL are far less common than injuries to other knee structures, such as the anterior cruciate ligament (ACL) or the menisci. The incidence of PCL injuries has varied dramatically in the literature, ranging from 3% in the general population 9 to as high as 38% in the trauma setting in patients with acute knee hemarthrosis.…”

“…23,24 One possible explanation for the persistent posterior tibial laxity is femoral tunnel positioning. 5,8,25 Anatomic reconstruction on the femoral side requires an accurate and reproducible method to guide tunnel placement. The "clock-face" method has been frequently reported as a guide for femoral tunnel placement; however, poor reproducibility has been noted among surgeons who use this method.…”