Measurement of Ligament's Deformation by Arthroscopy

S. Hirokawa and S. Miyagano (Japan)


In-vivo Measurement, Arthroscopy, Endoscope, ACL, Shape from Shading


The object of this study is to establish in vivo measurement system of strain distribution on the human knee ligaments. To solve technical and ethical problems subject to living body, we planned to use less invasive arthroscopy for a measurement. We applied such theory to the arthroscopic images that reconstructs a 3D shape of an object from its gray scale image. In the experiment, an industrial endoscope was used for its less aberration instead of the conventional arthroscopy. All parametric data necessary for calculation were introduced from the calibration image. The accuracy of our method was checked from known subjects. After that, the anterior cruciate ligament (ACL) of swine hind leg was used for the measurement. Femur and tibia were set on the specially designed fixture. The pictures of the ACL were taken at various knee flexion angles. Three-dimensional coordinal data were obtained by the level set method from the brightness data on the processed image of the ACL. Then three-dimensional shape of the ACL surface was reconstructed.

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