DETERMINATION OF THE IN-SITU FORCES IN THE HUMAN POSTERIOR CRUCIATE LIGAMENT USING ROBOTIC TECHNOLOGY - A CADAVERIC STUDY

We examined the in situ forces in the posterior cruciate ligament as w ell as the force distribution between its anterolateral and posteromed ial bundles. Using a robotic manipulator in conjunction with a univers al force-moment sensor system, we applied posterior tibial loads from 22 to 110 N to the joint at 0 degrees to 90 degrees of knee flexion. T he magnitude of the in situ force in the posterior cruciate ligament a nd its bundles was significantly affected by knee flexion angle and po sterior tibial loading, In situ forces in the posterior cruciate ligam ent ranged from 6.1 +/- 6.0 N under a 22-N posterior tibial load at 0 degrees of knee flexion to 112.3 +/- 28.5 N under a 110-N load at 90 d egrees The force in the posteromedial bundle reached a maximum of 67.9 +/- 31.5 N at 90 degrees of knee flexion, and the force in the antero lateral bundle reached a maximum of 47.8 +/- 23.0 N at 60 degrees of k nee flexion under a 110-N load. No significant differences existed bet ween the in situ forces in the two bundles at any knee flexion angle. This study provides insight into the knee flexion angle at which each bundle of the posterior cruciate ligament experiences the highest in s itu forces under posterior tibial loading. This information can help g uide us in more accurate graft placement, fixation, and tensioning, an d serve as an assessment of graft performance.