Observations of the proximal tibia in total knee arthroplasty.

Relatively little has been written concerning the proximal tibia in total knee arthroplasty. Few authors have looked at landmarks and guidelines for tibial tray preparation and tibial tray orientation. The current study showed that a line drawn 1 mm medial to the medial border of the tibial tubercle and going through the midsulcus of the tibial spines (the midsulcus line) provided a reproducible landmark for the tibia, and when a perpendicular cut was made relative to this line, 46 of 50 knees were cut in appropriate alignment. In addition, it has been said that the tibial tray should be rotated externally to approximately the medial 1/3 of the tubercle to maximize function. The current study showed that when the tibia is allowed to float in a functional position relative to the femoral implant, the tibial external rotation was only 2 mm lateral from the medial age of the tibial tubercle; this is far less than the medial 1/3 of the tubercle and close to the starting point of the midsulcus line.