1. The Effects of Freezing on the Properties of Bovine Meniscus Scott Morgan

2. What Is Meniscus? Semi-lunar fibrocartilage Semi-lunar fibrocartilage LateralLateral MedialMedial

3. Importance? Provide smooth, low friction articulating surfaces Provide smooth, low friction articulating surfaces Serve as shock absorbers and stabilizers Serve as shock absorbers and stabilizers When injured and/or removed When injured and/or removed Degeneration leading to osteoarthritisDegeneration leading to osteoarthritis Knee movement becomes more difficultKnee movement becomes more difficult

4. Why freezing? Literature review (Proctor et al, J of Ortho R, 1989) Literature review (Proctor et al, J of Ortho R, 1989) Experimental menisci described as freshExperimental menisci described as fresh Frozen to microtome twice during slicingFrozen to microtome twice during slicing Menisci are roughly 70% water Menisci are roughly 70% water No studies to determine effect of freezing on material propertiesNo studies to determine effect of freezing on material properties

5. Materials & Methods Bovine menisci Bovine menisci Obtained from local slaughterhouse Medial meniscus only  to reduce variability Medial Lateral

6. Methods Treatment Groups  5 Treatment Groups  5 Control (Fresh)Control (Fresh) 4 Freeze/Thaw Cycle (FTC) Group4 Freeze/Thaw Cycle (FTC) Group 1 FTC = 5 days frozen, 2 days thawed 1 FTC = 5 days frozen, 2 days thawed 2 FTC 2 FTC 3 FTC 3 FTC 4 FTC 4 FTC

7. Methods

8. Methods 12 Menisci per treatment 12 Menisci per treatment Minimum of 5 slicesMinimum of 5 slices Maximum of 15 slicesMaximum of 15 slices Thickness measured Thickness measured Dial caliperDial caliper Sandpaper glued to ends Sandpaper glued to ends Facilitated gripping in fixtureFacilitated gripping in fixture Provided gage lengthProvided gage length

9. Methods MTS servohydraulic mechanical testing system MTS servohydraulic mechanical testing system Computerized data acquisitionComputerized data acquisition Custom gripping jigCustom gripping jig Performed tensile test Performed tensile test

10. Methods Tensile test Tensile test 1 N preload1 N preload Photograph for later digital analysis for specimen dimensionsPhotograph for later digital analysis for specimen dimensions 0.5 mm/min crosshead speed0.5 mm/min crosshead speed Tensile tested until failureTensile tested until failure

11. Methods Data analysis Data analysis Digital image analysisDigital image analysis Specimen dimensions from photos Specimen dimensions from photos Calculate stress & strainCalculate stress & strain Plot stress-strain curve Plot stress-strain curve (Wainwright, 1976)

12. Statistical Analysis Compared menisci within each treatment Compared menisci within each treatment Look for individual variabilityLook for individual variability Compared treatment groups Compared treatment groups ANOVA ANOVA Multiple comparisons – Tukey-KramerMultiple comparisons – Tukey-Kramer

15. Conclusions Large variability between specimens Large variability between specimens Increasing FTC’s lead to increasing variabilitityIncreasing FTC’s lead to increasing variabilitity There appears to be little to no effect of multiple FTCs on the tensile strength of the circumferential collagen fibers There appears to be little to no effect of multiple FTCs on the tensile strength of the circumferential collagen fibers

16. Current Changes in the specimens Changes in the specimens TextureTexture Ease of slicingEase of slicing Creep & Relaxation Testing Creep & Relaxation Testing Design of new apparatus Design of new apparatus Compression indenterCompression indenter New experimental procedure New experimental procedure Meniscus from other species Meniscus from other species OvineOvine PorcinePorcine

17. Acknowledgments Dr. Carolyn Skurla Dr. Carolyn Skurla Daniel Bland Daniel Bland Zachary Kelm Zachary Kelm Erik Schaefer Erik Schaefer Christopher Towe Christopher Towe David Webster David Webster