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The Effects of Freezing on the Properties of Bovine Meniscus

The Effects of Freezing on the Properties of Bovine Meniscus. Scott Morgan. What Is Meniscus?. Semi-lunar fibrocartilage Lateral Medial. Importance?. Provide smooth, low friction articulating surfaces Serve as shock absorbers and stabilizers When injured and/or removed

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The Effects of Freezing on the Properties of Bovine Meniscus

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

  2. What Is Meniscus? • Semi-lunar fibrocartilage • Lateral • Medial

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

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

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

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

  7. Methods

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

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

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

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

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

  13. Conclusions • Large variability between specimens • Increasing 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

  14. Current • Changes in the specimens • Texture • Ease of slicing • Creep & Relaxation Testing • Design of new apparatus • Compression indenter • New experimental procedure • Meniscus from other species • Ovine • Porcine

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

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