Evaluation of In Situ Graft Forces of a 2-Bundle Tibial Inlay Posterior Cruciate Ligament Reconstruction at Various Flexion Angles

Purpose: The purpose of this study is to evaluate a posterior cruciate ligament (PCL) reconstruction using a 2-bundle (anterolateral [AL] and posteromedial [PM]) posterior tibial inlay reconstructive technique fixed at various degrees of flexion. Methods: Eight human cadaveric knee specimens underwent a 2-bundle/posterior inlay PCL reconstruction. A testing apparatus was developed with force gauges placed on the AL and PM bundles, respectively. The PCL 2-bundle complex was pretensioned and placed through an arc of motion from 0° to 105° with measurement obtained at 15° increments. Testing conditions included 3 different tension parameters of the AL and PM bundles: (1) AL and PM bundles both at 90°, (2) AL and PM bundles both at 45°, and (3) differential tensioning the AL bundle at 90° and the PM bundle at 0°. Results: The results revealed that tensioning of the AL bundle at 90° and PM bundle at 0° produced reciprocal in situ forces similar to the native PCL. Through a complete knee arc of motion, at least 1 of the 2 bundles maintained tension in a reciprocal fashion. Data from the other reconstructive conditions revealed there was significant and excessive in situ loads above the pretensioned loads transmitted through the PM bundle with increased extension. Conclusions: This in vitro PCL reconstructive study using an anatomic tibal inlay and 2-bundle (AL and PM) approach with the AL bundle fixed at 90° and the PM bundle at 0° flexion produces a symmetrical reciprocal force pattern with 1 limb of the graft under continuous tension throughout a full arc of motion, whereas the other 2 testing conditions (AL/PM at 45/45 and 90/90) produce excessive force in the PM bundle with lower degrees of flexion. Clinical Relevance: This cadaver study showed the PCL technique using 2-bundle/tibial inlay technique and fixation of the AL bundle at 90° of flexion and the PM bundle at 0° flexion reproduced anatomic in situ graft forces in a reciprocal pattern.