A method for measuring shapes of anatomical surfaces.
Armstrong-TJ; Chaffin-DB; Foulke-JA
J Biomech 1979 May; 12(5):397-399
A three dimensional point encoder was built to record surface geometries of hand/wrist structures during the course of study of biomechanical aspects of carpal tunnel syndrome. The encoder consists of a pointer that slides axially and rotates in perpendicular planes. It is instrumented with a linear voltage differential transformer and with two potentiometers such that voltages proportional to the axial and two angular positions of the pointer are produced. These voltages correspond to the spherical coordinates of the pointer. Encoder voltages were measured via an analogue/digital (A-D) converter and an HP 2100 computer. Each dimension of the system was calibrated by measuring the voltage differences between known positions of the pointer. The computer was then programmed to calculate spherical coordinates from A-D converter voltages of each point and then to convert the results to Cartesian coordinates. The data points were stored in a file in disc memory for later plotting and analysis. Sample point locations along the flexor digitorum profundus tendon of the second digit in three positions of a partially dissected wrist were presented. Such a data encoder should be of help to those interested in recording shapes and positions of anatomical structures.
NIOSH-Publication; NIOSH-Grant; Musculoskeletal-system-disorders; Diagnostic-techniques; Measurement-equipment; Anatomy
Industrial & Operations Engr University of Michigan 2260 G G Brown Laboratory Ann Arbor, Mich 48109
Journal of Biomechanics
University of Michigan at Ann Arbor, Ann Arbor, Michigan