1. Connective Tissue/Bone

2. Connective Tissue ligaments tendons bones synovium labra cartilage bursa fat pads etc.

3. Connective Tissue Extra-cellular matrix Cells - blast – synthesis of extracellular matrix (collagen) - clast – break-down extracellular matrix

4. Extra-cellular matrix Non-Fibrous Ground Substance - glycoproteins & proteoglycans - H 2 O binding, structure, protection

5. Extra-cellular matrix Fibrous - collagen (white) - elastin (yellow)

6. Bone Hardest CT Protects Links Attachment site Facilitates movement (lever)

7. Components of Bone Inorganic (rigid/hard) - Ca and PO 3 (65-70% of wt.) Organic (flexible/resilient) - collagen (25-30% of wt.)

8. Components of Bone Ground Substance - GAG H 2 0 (25% of wt.) Cells

9. Structure of Bone Fundamental unit: osteon or haversian system  Concentric layers/lamellae  Collagen is intertwined (  strength)

10. Structure of Bone Cortical/Compact - outer layer - more dense Withstands compression > tensile > shear

11. Mechanical Behavior Affected by: loading mode – type of force/torque rate of loading frequency of loading geometric characteristics mechanical properties of materials

12. Loading Mode Tensile - attachment sites Compressive - vertebra Shear - fx in cancellous bone / tibial plateau Bending

13. Loading Mode torsion – twisting about the longitudinal axis spiral fx. combined loading – explains most fractures

14. Rate of Loading Bone is viscoelastic Load to failure rate almost doubled High loading Rate Low loading Rate Load Deformation

15. Frequency of Loading Load Repetition Injury

16. Stress/Fatigue Fx Model Strenuous Exercise Fatigued Muscle Loss of Shock Absorbing Capacity Altered Gait Abnormal Loading Altered Stress Distribution High Compression Slow Combined Process High Tension Fast Oblique Cracks Debonding of Osteons/transverse cracks Oblique Fracture Transverse Fracture

17. Geometric Properties  Stress = force/area (large the cross- sectional area  stiffer and stronger the bone) Longer the bone the more susceptible to bending moments

18. Effects of Immobilization Load Normal Immobilized Deformation

19. Effects of Immobilization Load Normal Immobilized Deformation