[The Study of a Relaxed Patient Position in Whole Lower Limb Radiography]

In whole lower limb radiography, a position of the patella is the center of the knee with a leg slight internal rotation (a knee frontal position). However, we revised the positioning to stand naturally so that we can evaluate the lower limb alignment while standing more naturally (a relaxed patient position). In this study, we compared a lower limb alignment of a relaxed patient position and a knee frontal position.

The images of 84 patients who underwent artificial joint replacement surgery were analyzed, separately for the group with artificial joint and without it. The Mikulicz line (the functional axis of the lower limb connecting the center of the femoral bone and the ankle joint) is drawn on the image of the whole lower limb radiography. The intersection between the proximal tibia joint surface and the Mikulicz line defines the percentage of mechanical axis (%MA). Furthermore, we compared the %MA between a relaxed patient position and a knee frontal position and assessed them by the Bland-Altman analysis.

The correlation coefficient (R) was 0.792 in the group with artificial joint and 0.856 in the group without artificial joint. There was a fixed error between the relaxed patient position and the knee frontal position.

The %MA tends to be smaller in a relaxed patient position than in a knee frontal position. Besides, it is found that there is a correlation between them.