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Micro-CT based analysis of Subchondral Vessel Density in a Model of Osteoarthritis

Micro-CT based analysis of Subchondral Vessel Density in a Model of Osteoarthritis. Kasun Attanapola. Supervisor: Dr. Holdsworth Technical Support: David D. McErlain. Acknowledgements. Background: Osteoarthritis (OA). Osteoarthritis (OA) is the most common form of arthritis

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Micro-CT based analysis of Subchondral Vessel Density in a Model of Osteoarthritis

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  1. Micro-CT based analysis of Subchondral Vessel Density in a Model of Osteoarthritis KasunAttanapola

  2. Supervisor: Dr. Holdsworth Technical Support: David D. McErlain Acknowledgements

  3. Background: Osteoarthritis (OA) • Osteoarthritis (OA) is the most common form of arthritis • Degenerative disease causing erosion of articular cartilage, and subchondral bone • 4 million Canadians affected, between 16-64 years • No current therapy, only surgical intervention once disease has reached end-stage

  4. Methods • Investigating effects of OA on a Rat model • Anterior Cruciate ligament severed to increase shear and induce OA. • Rats injected with a contrast agent “microfil” (MV-122) prior to imaging, enhance contrast of blood vessels. • Ex vivo micro-CT imaging used to image rat knees at set time points (0.028mm).

  5. Methods • Center of the joint in the Sagittal plane is first located. • Center of the Medial Joint Compartment in the Coronal plane is located. • Least joint space is then located from the sagittal plane. This is the center slice. • 1mm to anterior, posterior of the central slice lies the other measurement planes.

  6. Methods • Lay a 5 X 10 grid on the medial joint compartment and point count Bone, Tissue & Vessel Volume fractions. • For each joint, point counts are performed at slices named before. • Average volume fractions are then calculated for the knee joint. • Bone and vessels show high contrast while tissue has lower contrast. Vessels are continuous as you pan through slices and this is how we differentiated between vessel and bone.

  7. Methods • Grid laid on medial joint compartment before a point count.

  8. Results Rats with OA show a lower vessel volume fraction(VVF) than healthy rats

  9. Results • Table AnalyzedUnpaired, two-tailed t-test • Column AControl • vsvs • Column B OA • Unpaired t test • P value =0.0008 • P value summary*** • Are means significantly. different? - (P < 0.05)Yes • One- or two-tailed P value? - Two-tailed • t,df - t=5.27 df=8 How big is the difference? Mean ± SEM of column A-4.62 ± 0.510 N=5 Mean ± SEM of column B-1.72 ± 0.210 N=5 Difference between means-2.90 ± 0.551 95% confidence interval-1.63 to 4.18 R squared0.776 F test to compare variances F,DFn, Dfd-5.86, 4, 4 P value-0.1150 P value summary-ns Are variances significantly different? –No.

  10. Results P value of 0.008 suggests that joints with OA have low vessel density. Bone degradation is also seen in joints with OA 20 weeks control 20 weeks OA

  11. Discussion Findlay DM. “Vascular pathology and osteoarthritis”, Rheumatology. 46(12):1763-8, 2007.

  12. Discussion and Future Work • OA affects bone perfusion and degrades bones at joints. • Can investigate changes in VVF at other time points. • See if increasing blood perfusion will reverse affects of OA.

  13. Conclusion • From the data obtained it seems that OA reduces blood perfusion in Subchondral bone.

  14. ThankYou

  15. Questions?

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