1. 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

2. Outline Introduction Materials and methods Result Discussion 2

3. 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

4. Outline Introduction Materials and methods Result Discussion 4

5. 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

6. Materials and methods 6

7. 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

8. Materials and methods In addition to quantifying variances ◦ closest approximation of the true cartilage thickness  utilized a cylindrical object with two specific radii  25.52-mm on one side  27.46-mm on the other 8

9. Materials and methods 9

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

11. Outline Introduction Materials and methods Result Discussion 11

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

13. Result 13

14. Result 14

15. Outline Introduction Materials and methods Result Discussion 15

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

17. End 17