Biomechanical evaluation of double bundle augmentation of posterior cruciate ligament using finite element analysis

Posterior cruciate ligament injuries commonly occur during sports activities or motor vehicle accidents. However, there is no previous comparison study of single bundle reconstruction, double bundle reconstruction, and double bundle augmentation with respect to biomechanical characteristics such as stability and ligament stress.

A three-dimensional finite element model of a lower extremity including femur, tibia, cartilage, meniscus, collagen fibers, and four major ligaments was developed and validated. In addition to the intact, posterior cruciate ligament injured, single bundle reconstruction, double bundle reconstruction, and double bundle augmentation models were developed. Then, the posterior and rotational tibial translations as well as the ligament stresses were predicted for 89 N posterior force and 3 Nm internal torque, respectively, in the normal (no secondary deficiency) and the secondary deficiency cases using finite element analysis.

The posterior stability and ligament stresses following double bundle augmentation were superior to those of single and double bundle reconstructions, especially after secondary deficiency in the reconstructed grafts, despite little difference in posterior stability between double bundle reconstruction and augmentation in the normal case. Similarly, the double bundle augmentation had the greatest rotational stability while there was little advantage in ligament stress compared to those of the other reconstruction method.

Double bundle augmentation has advantages with regard to posterior and rotational stabilities as well as ligament stress in comparison with other reconstruction methods, especially following secondary deficiencies in the reconstructed grafts.