Brief Reports

Development of a method to assess alignment of the foot and lower leg

Shinya Ito, RPT, MS of Health Science, Yutaka Tomita, Prof., Dr. Eng., Dr. Med. Sci, Shigeo Tanabe, Ass. Prof., Dr. Eng
Jpn J Compr Rehabil Sci 4: 80-83, 2013

Purpose: Three-dimensional analyses of the foot and lower leg have been restricted to large-scale research facilities, since such analyses require a large experimental area and expensive measurement systems. Therefore, we developed a new threedimensional method of analyzing still pictures using commercially available digital cameras, and applied it to clinical use.
Methods: We used three digital cameras. One was set 6 m behind the subject, while the other two were placed at 45 degrees to the right and left sides of the first camera, each the same distance from the subject. We used a plaster model of a lower leg and foot, on which several markers were mounted. The positions of the three-dimensional coordinates of the markers were computed by triangulation from the pictures taken with the three cameras, and the accuracy was verified.
Results: The average reading error was 0.6 mm, and the average and maximum repetition errors were 1.3 mm and 1.6 mm, respectively. Comparison with direct evaluation was found to be 2.3% at maximum. These results showed that the method is highly reliable.
Conclusion: Although a three-dimensional analysis using this method has the limitation of still picture analysis, it may be useful in many clinical applications because it requires only inexpensive apparatus and a small experimental area.

Key words: foot-lower leg alignment, three-dimensional analysis, digital camera, accuracy

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