This study was undertaken to determine the relationship between physical factors and vertical axial rotation through the tibial shaft caused by passive knee and subtalar joint rotation in healthy subjects. The data collected were analyzed in detail to determine the relationship between various physical parameters, such as age, body mass, height, and sex, and tibial rotation. A total of 484 healthy subjects were examined with the measuring the vertical axial rotation through tibial shaft (WARTS) system. Evaluators passively measured internal and external tibial rotation. The effects of any 2 simultaneous variables and outcomes with a single variable were analyzed; the results were documented graphically. Data were also examined through multiple regression analysis (stepwise regression). Agreement between right and left internal tibial rotations was observed to be strong, as was agreement between right and left external rotations. Female patients exhibited a greater amount of internal/external rotation than did male patients. Differences between female and male patients were noted to be significant. A highly significant and inverse relationship between physical parameters and tibial rotations was noted. Findings suggest that as age, body mass, and height increase, tibia] motion is reduced.