Three dimensional finite element analysis of the influence of posterior tibial slope on the anterior cruciate ligament and knee joint forward stability.

OBJECTIVE: To explore the biomechanical influence of posterior tibial angle on the anterior cruciate ligament and knee joint forward stability. METHODS: The left knee joint of a healthy volunteer was scanned by CT and MRI. The data were imported into Mimics software to obtain 3D models of bone, cartilage, meniscus and ligament structures, and then Geomagic software was used to modify of the image. The relative displacement between tibia and femur and the stress of ACL were recorded. RESULTS: ACL tension was 12.195 N in model with 2 degrees PTS, 12.639 N in model with 7 degrees PTS, 18.658 N in model with 12 degrees PTS. the relative displacement of the tibia and femur was 2.735 mm in model with 2 degrees PTS, 3.086 mm in model with 7 degrees PTS, 3.881 mm in model with 12 degrees PTS. In the model with 30 degrees flexion, the maximum tension of ACL was 24.585 N in model with 2 degrees PTS, 25.612 N in model with 7 degrees PTS, 31.481 N in model with 12 degrees PTS. The relative displacement of the tibia and femur was 5.590 mm in model with 2 degrees PTS, 6.721 mm in model with 7 degrees PTS, 6.952 mm in model with 12 degrees PTS. In the 90 degrees flexion models, ACL tension was 5.119 N in model with 2 degrees PTS, 8.674 N in model with 7 degrees PTS, 9.314 N in model with 12 degrees PTS. The relative displacement of the tibia and femur was 0.276 mm in model with 2 degrees PTS, 0.577 mm in model with 7 degrees PTS, 0.602 mm in model with 12 degrees PTS. CONCLUSION: The steeper PTS may be a risk factor in ACL injury.