Two-bundle posterior cruciate ligament reconstruction - An in vitro analysis of graft placement and tension

This study had two purposes: first, to determine how femoral attachment loc ation affects the load sharing between the two bundles of a Y-type posterio r cruciate ligament reconstruction, and second, to determine how the bundle s, separately and in combination, control posterior tibial translation thro ughout the full range of knee flexion, One and two-bundle reconstructions w ere performed in 12 cadaveric knees. The one-bundle reconstructions were at tached within the femoral posterior cruciate ligament footprint at one of t hree locations, high and shallow (S-1), mid and shallow (S-2) or mid and de ep (D). The two-bundle reconstructions comprised an S-1 bundle with either an S-2 or a D bundle. Posterior translation and bundle tension were measure d as the knee was flexed from full extension to 120 degrees of flexion whil e a posterior force of either 50 or 100 N was applied to the proximal tibia . The shallow one-bundle reconstruction restored posterior translation to w ithin 2 mm of that of the intact knee over the entire range of knee flexion . The deep reconstruction did not control abnormal posterior translation ab ove 45 degrees, The tension in the shallow bundles increased with knee flex ion, and the deep bundle tension remained nearly constant throughout knee f lexion. Both two-bundle reconstructions controlled posterior translation, b ut with different load-sharing characteristics. The S-1-S-2 configuration r esisted posterior tibial translation as both bundles became taut in flexion . in contrast, the S-1-D configuration resisted posterior translation in a reciprocal fashion with the D bundle tension being the greatest in extensio n and the S-1 bundle tension being the greatest tension in flexion.