DECREASED POSTERIOR TIBIAL SLOPE INCREASES STRAIN IN THE POSTERIOR CRUCIATE LIGAMENT FOLLOWING TOTAL KNEE ARTHROPLASTY

The purpose of this study was to measure the strain in the posterior c ruciate ligament as a function of knee flexion angle and posterior tib ial slope following total knee arthroplasty with a posterior cruciate ligament-retaining design. Posterior cruciate ligament strain was meas ured in seven fresh-frozen cadavers for posterior tibial slopes of 10 degrees, 8 degrees, and 5 degrees. For all three levels of tibial slop e tested, strain in the posterior cruciate ligament increased with inc reasing flexion angle to approximately 100 degrees and then decreased with increasing flexion. The strain measured at 8 degrees posterior ti bial slope was greater than that measured at 10 degrees, but the diffe rence was not significant. The strain measured at 5 degrees posterior slope was significantly greater than strain measured at both 8 degrees and 10 degrees. This increased strain may result in altered knee kine matics and reduced range of motion at higher flexion angles.