Finite element analysis of the influence of the posterior tibial slope on mobile-bearing unicompartmental knee arthroplasty.
BACKGROUND
The most common modes of failure reported in unicompartmental knee arthroplasty (UKA) in its first two decades were wear on the polyethylene (PE) insert, component loosening, and progressive osteoarthritis in the other compartment. The rates of implant failure due to poor component positioning in patients who have undergone UKA have been reported. However, the effect of the posterior tibial slope on the biomechanical behavior of mobile-bearing Oxford medial UKA remains unknown.


METHODS
We applied finite element (FE) analysis to evaluate the effects of the posterior tibial slope in mobile-bearing UKA on the contact stresses in the superior and inferior surfaces of PE inserts and articular cartilage as well as the forces exerted on the anterior cruciate ligament (ACL). Seven FE models for posterior tibial slopes of -1°, 1°, 3°, 5°, 7°, 9°, and 11° were developed and analyzed under normal-level walking conditions based on this approach.


RESULTS
The maximum contact stresses on both the superior and inferior surfaces of the PE insert decreased as the posterior tibial slope increased. However, the maximum contact stress on the lateral articular cartilage and the force exerted on the ACL increased as the posterior tibial slope increased.


CONCLUSIONS
Increasing the tibial slope led to a reduction in the contact stress on the PE insert. However, a high contact stress on the other compartment and increased ACL force can cause progressive osteoarthritis in the other compartment and failure of the ACL.
['Koh|Yong-Gon|YG|', 'Park|Kyoung-Mi|KM|', 'Kang|KiWon|K|', 'Kim|Paul Shinil|PS|', 'Lee|Young Han|YH|', 'Park|Kwan Kyu|KK|', 'Kang|Kyoung-Tak|KT|']
D019645:Arthroplasty, Replacement, Knee D001696:Biomechanical Phenomena D003198:Computer Simulation D020342:Finite Element Analysis D000077107:Gait Analysis D006801:Humans D007719:Knee Joint D007720:Knee Prosthesis D008954:Models, Biological D017755:Prosthesis Fitting D013314:Stress, Mechanical
Finite element analysis Posterior tibial slope Mobile-type unicompartmental knee arthroplasty