Background and objective: The knee joint is a complex structure which is vulnerable to injury due to various types of loadings as a consequence of walking, running, stair climbing, etc. Total knee arthroplasty (TKA) is a widely used and successful orthopedic procedure which during that the posterior cruciate ligament (PCL) can either be retained or substituted. Different surgical techniques suggest retention or sacrifice of the PCL in TKA for the treatment of osteoarthritis which may alter the post-op outcomes. The objective of this study was to evaluate the biomechanical role of PCL after TKA surgery using finite element (FE) modeling.
Methods: A three-dimensional (3D) FE model of the prosthetic knee was developed and its validity was compared to available studies in literature. Further, the effect of the retention or removing of the PCL as well as its degradation (i.e. variation in mechanical properties) and angle on knee biomechanics were evaluated during a weight-bearing squatting movement.
Results: The validity of the intact model were confirmed. The results revealed higher stresses in the PCL and tibial insert at higher femoral flexion angles. In addition, the effect of variations in the stiffness of the PCL was found to be negligible at lower while considerable at higher femoral flexion angles. The variations in the elevation angle of the PCL from 89° to 83° at the critical femoral angles of 60° and 120° showed the highest von Mises stresses in the tibial insert.
Conclusions: The results have implications not only for understanding the stresses in the prosthetic knee model under squat movement but also for providing comprehensive information about the effects of variations in the PCL stiffness and balancing on the induced stresses of the PCL and tibial insert.
Keywords: Femoral prosthesis; Finite element analysis; Posterior cruciate ligament; Total knee arthroplasty; Von Mises stress.
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