BACKGROUND: Total knee arthroplasty serves as an effective intervention for the treatment of late-stage knee joint disorders. However, prosthetic liners are prone to wear and failure due to internal stress variations, resulting in limited lifespan and decreased postoperative patient activity. Addressing how to enhance prosthetic design to meet a broader range of patient needs constitutes a significant focus in prosthesis research.
OBJECTIVE: Based on the morphological design of the meniscus, we propose an asymmetric design prosthesis and compare it with a symmetric posterior stabilized prosthesis. The stress distribution patterns and variations in the contact area of the liners for both prostheses were analyzed to explore whether the asymmetric prosthesis design offers advantages over the symmetric design.
METHODS: Using the finite element method, we simulated the osteotomy and prosthesis assembly in a knee osteoarthritis patient. Two different prostheses (asymmetric design and posterior stabilized) were employed to establish post-total knee arthroplasty knee joint models. Under flexion conditions at 0°, 10°, 20°, and 30°, we investigated the Mises stress on the femoral and tibial components as well as the liner. Additionally, by comparing the contact area on the inner and outer sides of the liner, we aimed to explore the changes in biomechanics and alterations in motion behavior in the post-total knee arthroplasty knee joint.
RESULTS AND CONCLUSION: (1) Throughout the flexion range from 0 to 30 degrees, the Mises stress peak on the liner exhibited a trend of initial decrease followed by an increase, with the stress on the medial side consistently surpassing that on the lateral side. (2) In comparison to the posterior stabilized prosthesis, the asymmetrically designed prosthesis demonstrated smaller stress peaks. At a flexion angle of 30 degrees, the Mises stress peak values of the medial and lateral parts of the asymmetric prosthesis were 15.81 MPa and 11.95 MPa, and those of the posterior stabilization prosthesis were 16.70 MPa and 13.76 MPa. The difference of Mises stress on the medial part was 5.33%, and the difference of Mises stress on the lateral part was 13.15%. Comparing the peak Mises stress on the femoral and tibial components, the asymmetric component was always lower than the posterior stable component during knee flexion.
(3) In the upright position at 0 degrees, the medial contact area of the posterior stabilization prosthesis was 17.96 mm2, and the lateral contact area was
34.10 mm2. The contact area on the inner and outer sides of the asymmetric design prosthesis liner was 105.47 mm2 and 107.80 mm2, respectively, indicating a larger contact area with a smaller difference between the inner and outer sides. (4) These results suggest that the biomechanical performance of the asymmetric prosthesis is superior, contributing to the maintenance of knee joint stability and improved joint mobility. This design, to a certain extent, mimics the rotational motion mechanism of the knee joint about the medial condyle as an axis, making it a more effective choice for knee joint prosthesis selection.