Fig. 3.

Measurement of bar size from the shoulder width. The shoe is placed approximately 70° abduction to the rod. The metal plate measures 2” and is placed ½” proximal from the tip of heel. The metal rod is welded halfway of the metal plate. Applying simple trigonometry principles, the right angled triangle at heel has one angle 20° and other 70° (abduction). Using the cosine 70° (=0.34) values with the hypotenuse measuring 1 ½″ (half of metal plate + distance from tip of heel to plate), the base comes out to be .51″. For two shoes, this distance totals (.51″ × 2) (2.5 cm). This portion of metal rod was assumed to compensating for the distal placement of rod from the tip of heel, width of heel, flare of heel cup and the shoe angulations with respect to rod. The predicted bar length was derived by adding 2.5 cm to the measured shoulder width.