It has been reported that patellar position becomes lower after the high tibial osteotomy. However, the most commonly used methods for determining patellar height, namely, the Insall-Salvati and Blackburne-Peel methods, use a reference point on the tibia. Therefore, when a surgery is performed on the proximal tibia, the point of reference itself shifts, which may generate spurious values indicating a change when nothing has occurred. We developed a new method for measuring the change in patellar height in relation to the femur under the condition that the patella articulates with the femur, and not with the tibia. Contrary to published reports, we found that the patella height is unchanged or moves slightly proximal in relation to the femur following high tibial osteotomy.