ESTIMATION OF CARTILAGE THICKNESS FROM JOINT SURFACE SCANS: COMPARATIVE ANALYSIS OF COMPUTATIONAL METHODS Author :Frank Heuer, Mark Sommers, John B. Reid III, Michael Bottlang Source :BED-Vol. 50, 2001 Bioengineering Conference ASME 2001 Speaker : Ren-LI Shen Advisor : Ku-Yaw Chang 1

Outline Introduction Materials and methods Result Discussion 2

Introduction Cartilage thickness and volume ◦ characterize normal joints ◦ delineate joint degenerative disease Compute cartilage thickness and volume from high-resolution joint geometry scans ◦ three distinct algorithms 3

Outline Introduction Materials and methods Result Discussion 4

Materials and methods Joint of a human cadaveric talus ◦ obtained a laser displacement sensor ◦ scanning of a 31-mm x 34-mm region of interest ◦ over 40,000 digitized surface points Talar joint surface ◦ intact articular cartilage (Atc) ◦ subchondral bone surface (Atb) 5

Materials and methods 6

Use PV-Wave to compute cartilage thickness from Atc and Atb in three distinct approaches ◦ a) vertical distance ◦ b) proximity method ◦ c) normal distance 7

Materials and methods In addition to quantifying variances ◦ closest approximation of the true cartilage thickness  utilized a cylindrical object with two specific radii  mm on one side  mm on the other 8

Materials and methods 9

Defined thickness T=1.94-mm ◦ idealized constant cartilage thickness distribution 10

Outline Introduction Materials and methods Result Discussion 11

Result 12 Cartilage thickness variances ◦ depicted as a grey-scale image

Result 13

Result 14

Outline Introduction Materials and methods Result Discussion 15

Discussion The other two methods ◦ based on magnetic resonance imaging ◦ based on stereophotogrammetry 16

End 17