Effect of posterior cruciate ligament rupture on biomechanical features of the medial femoral condyle

Objective: To investigate the biomechanical impact of rupture of the posterior cruciate ligament (PCL) and its various bundles on the medial femoral condyle. Methods: Twelve fresh human cadaveric knee specimens were divided into four groups: PCL intact, anterolateral band (ALB) rupture, posteromedial band (PMB) rupture and PCL complete rupture groups according to the purpose and order of testing. Strain in the middle of the medial femoral condyle was measured under different loads (200–800 N) at 0°, 30°, 60°, and 90° of knee flexion. Results: At 0° of knee flexion, compared with the PCL intact and ALB rupture groups, strain on the medial femoral condyle increased in the PMB rupture and PCL complete rupture groups under all loading conditions. There was no statistical difference between the PMB rupture and PCL complete rupture groups. At 30°, 60° and 90° of knee flexion, compared with the PCL intact group, increase in strain on the medial femoral condyle was noted in the ALB rupture group under higher loading conditions (600 N and 800 N) and PCL complete rupture group under all loading conditions. The PCL complete rupture group had higher strain on the medial femoral condyle than did the ALB rupture group under most loading conditions. Conclusion: At 0° of knee flexion, PMB rupture or PCL complete rupture can cause increase in strain on the medial femoral condyle. However, at 30°, 60° and 90° of knee flexion, ALB rupture or PCL complete rupture can cause increase in strain on the medial femoral condyle.