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

Introduction. Most surgeons that have performed kinematically aligned TKA have noticed an overall better clinical outcome, better motion, better patient satisfaction, and a quicker recovery than their patients treated with mechanically aligned TKA. Materials and Methods. We prospectively followed all 128 knees who underwent primary total knee arthroplasty. The Lysholm knee score and VAS scale was recorded initially and 12months after the surgery. Independent T-test was used for statistical analysis at probability level of 95%. SPSS for Windows (Version 12, Chicago, Illinois) was used. Results. VAS score and passive ROM; Not significant difference statistically. But improved compared the preoperative and postoperative data. WOMAC score and HSS score; Significantly improved statistically. Discussion. Our data suggest that kinematic alignment may lessen the surgical stress experienced by the patient, reduce the pain, and increase function of knee. There is a need for more studies to clarify benefits of kinematic alignment technique. Kinematically aligned TKA restores function by aligning the femoral and tibial components to the normal or prearthritic joint lines of the knee. We prospectively followed all 128 knees who underwent total knee arthroplasty. We assessed postoperative function using the VAS, WOMAC, HSS score and passive ROM. HSS score and WOMAC score were significantly improved statistically