A malalignment of the tibial component is a possible source of pain after a total knee arthroplasty. Currently, an internal rotation of the tibial component of 18 degrees is considered as a golden standard. The value was obtained as an average rotation in the osteoarthritic knees scheduled for a total knee arthroplasty.~It is known that the femur internally rotates with the increasing valgus alignment. It would seem logical that also tibial rotation correlates with the coronal limb alignment (varus-valgus). The plan is to measure the native tibial rotation (angle between the transposed epicondylar line and the posterior cruciate-tibial tuberosity line). In order to get the necessary accuracy a CT of lower legs will be obtained in patients waiting for the knee replacement. If there is a correlation between the angles the adjustment of the tibial component rotation more to the patient's anatomy could be proposed.~A secondary outcome measure is the possible correlation between the proximal femoral anteversion and the tibial tuberosity rotation. The hypothesis is that the extensor mechanism follows the proximal femoral orientation. With increasing femoral anteversion (increases with valgus angle) the femoral part of the knee rotates internally. In order to keep the extensor mechanism in the direction of walking, a more lateralized position of the tibial tuberosity is expected.
The primary aim of this study is to find a possible correlation between tibial tuberosity rotation and coronal leg alignment. If correlation exists, a more individual tibial component rotation might be proposed during a total knee arthroplasty.