Objective To explore the biomechanical function of PCL and its different bundles and examine the biomechanical impact of posterior cruciate ligament (PCL) integrity on the medial femoral condyle. Methods Twelve fresh human cadaveric knee specimens were subjected to different axial load (0-800 N) at 0°, 30°,60°, and 90°of knee flexion. Four surgical treatments were carried out for biomechanical testing: PCL intact, anterolateral bundle (ALB) rupture, posteromedial bundle (PMB) rupture and PCL rupure. During the test, strains of middle part of the medial femoral condyle were calculated. Results At O°knee flexion, increasing strain of the medial femoral condyle was detected in PMB rupture and PCL rupture under all loading conditions. No significant difference of strain of the medial femoral condyle was noted between PCL intact and ALB rupture under any loading conditions. Compared to PMB rupture, PCL rupture had not higher strain of the medial femoral condyle under all loading conditions. At 30°, 60° and 90° knee flexion, increasing strain of the medial femoral condyle was noted in ALB rupture under higher loading conditions and PCL rupture under all loading conditions. ALB rupture under lower loading conditions and PMB rupture under all loading conditions did not significantly increased strain of the medial femoral condyle. PCL rupture had higher strain of the medial femoral condyle than ALB rupture under most of loading conditions.Conclusion The data suggest that PMB is the major stabilizing bundle of PCL in full extension, ALB is the major stabilizing bundle of PCL in knee flexion, and both bundles function through the ROM in a codominant fashion. Partial and complete ruptures of PCL may have hazardous biomechanical impacts on the medial femoral condyle during normal movement.