Evaluation of in situ graft forces of a 2-bundle tibial inlay posterior cruciate ligament reconstruction at various flexion angles.

ABSTRACT

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 degrees to 105 degrees with measurement obtained at 15 degrees increments. Testing conditions included 3 different tension parameters of the AL and PM bundles (1) AL and PM bundles both at 90 degrees, (2) AL and PM bundles both at 45 degrees, and (3) differential tensioning the AL bundle at 90 degrees and the PM bundle at 0 degrees. RESULTS: The results revealed that tensioning of the AL bundle at 90 degrees and PM bundle at 0 degrees 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 degrees and the PM bundle at 0 degrees 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 degrees of flexion and the PM bundle at 0 degrees flexion reproduced anatomic in situ graft forces in a reciprocal pattern.