Effect of anterior and posterior horn suture stiffness on the biomechanical performance of a medial meniscal prosthesis: a finite element analysis

Background Meniscal injury is a common musculoskeletal disease. An artificial meniscal prosthesis is an effective choice for replacing allograft transplantation of the meniscus; however, the best method of fixation is still controversial. This finite element study aims to investigate the biomechanical effect of various anterior and posterior horn suture stiffnesses on a medial meniscal prosthesis under different knee flexion angles. Methods A validated three-dimensional finite element model of a human knee joint was used. A medial meniscal prosthesis of polycarbonate urethane (PCU) material was implanted, and spring elements were used to simulate the anterior and posterior horn fixation sutures and four levels of stiffness (13, 25, 62, and 200 N/mm) to represent available suture materials in the clinic. Knee flexion angles of 0°, 30°, and 60° were applied with combined anterior tibial load (134 N), compressive load (1150 N), and internal rotation moment (4 Nm). Tensile force in the sutures, meniscus translation (medial–lateral and anterior–posterior), and meniscus tibial contact stresses were extracted and analyzed. Results Increasing the suture stiffness resulted in increased force in the anterior horn sutures and the force in posterior horn sutures being mainly influenced by joint loading and not by suture stiffness. At 60° flexion, posterior horn tensile forces (50.11–52.35 N) were about 3.4–4.1 times greater than anterior horn tensile forces, which indicated the posterior horn as the major load-bearing structure. Increasing suture stiffness progressively decreased the medial–lateral and anterior–posterior displacements of the medial meniscus, and the 200 N/mm group of suture stiffnesses most closely approximated native meniscal kinematics. Medial tibial cartilage contact stress decreased with the increase of suture stiffness. It was found that 200 N/mm of suture stiffness most closely simulated the contact stress of the native knee for most loading conditions. The lateral compartment was not influenced by medial suture stiffness changes. Conclusion Suture stiffness is key to the overall biomechanical performance of artificial menisci. Stiffer fixation (200 N/mm) reduces the translation of the medial meniscal and tibial cartilage contact stress and restores the load distribution.