Abstract
Objective
Kinematically aligned total knee arthroplasty (TKA) is of increasing interest because this method may improve patient satisfaction. However, the biomechanics of kinematically aligned TKA remain largely unknown. Therefore, we analyzed whether the kinematic alignment method cause to increase the contact force on patellofemoral and tibiofemoral joints.
Methods
A musculoskeletal computer simulation was used to determine the effects of kinematically or mechanically aligned TKA. Patellofemoral and tibiofemoral contact forces were examined for a mechanically aligned model and a kinematically aligned model using finite element analysis.
Results
The peak contact stress on the patellofemoral joint in the kinematically aligned model was greater than that in the mechanically aligned model at 30° and 60°. Maximum peak contact stress was found at 30° flexion in the kinematically aligned model (73 MPa) and this was 221% higher than the stress in the mechanically aligned model (33 MPa). Similarly, peak contact stress of 33.0 MPa at 60° flexion occurred in the kinematically aligned model and this was 114% higher than that in the mechanically aligned model (29 MPa). The peak contact stress on the tibiofemoral joint in the kinematically aligned model was greater than that in the mechanically aligned model at 30°, 60° and 90° flexion. Maximum peak contact stress was found at 30° flexion in the kinematically aligned model (22 MPa) and this was 200% higher than the stress in the mechanically aligned model (11 MPa).
Conclusions
Kinematically aligned TKA may have increased risks for implant longevity. Therefore, a strict surgical indication, including age and implant design, is needed to achieve excellent longevity after kinematically aligned TKA.
