The literature indicates that the tibial component in total knee arthroplasty (TKA) should be placed in internal rotation not exceeding 18 to the line connecting the geometrical center of the proximal tibia and the middle of the tibial tuberosity. These landmarks may not be easily identifiable intraoperatively. Moreover, an angle of 18 is difficult to measure with the naked eye. The angle at the intersection of lines from the middle of the tibial tuberosity and from its medial border to the tibial geometric center was measured in 50 patients with normal tibia. The geometric center was determined on an axial CT slice at 10mm below the lateral tibial plateau and transposed to a slice at the level of the most prominent part of the tibial tuberosity. Similar measurements were performed in 25 patients after TKA in order to simulate the intra operative appearance of the tibia after making its proximal resection.Purpose
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