Assessment of Femoral Component Rotation after Total Knee Arthroplasty in Cases with Severe Varus deformity: Comparing Transepicondylar Axis reference points with Posterior Condylar Line

Perfect rotational positioning of femoral component in total knee arthroplasty is mandatory for good outcome، particularly in knees with severe varus. Posterior condylar line (PCL) and transepicondylar axis TEA are the two current methods used to determine the appropriate rotational positioning of femoral component. The aim of this study was to compare the accuracy of femoral component rotation after TKA، using either PCL or TEA reference points. In a retrospective study، 42 consecutive TKA candidates with severe varus knees were divided into two groups: In group I posterior condylar line، and in group II transepicondylar axis was considered as the primary landmark for rotational positioning. Erosion of medical femoral condylar was recorded in millimeters. One year after operation all the patients underwent CT scan and the angles between TEA and PCL of the prosthesis was meausured. The degree of knee flexion and also WOMAC scores were recorded. The female gender was prominent in both groups (81% in group 1، 85. 7% in group II). There was no significant femoral condylar erosion in either group. The mean Womac score in group 1 was 71. 4±17. 51 and 72. 07±15. 48 in group II (p=. 9). The degree of external rotation according to condylar twisting angle was 3. 35±1. 74 in group 1 and 1. 9±1. 7 in group 2 (p=. 009). In severe Knee-varus deformity، TEA landmark gives more external rotation position for femoral component، despite of lack of significant erosion in femoral condyle.