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Structural behavior of joints in human body

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Biomechanics

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Structural behavior of joints in human body

  1. 1. 1 Presentation on “Structural Behavior of Joints in Human Body” By: Shubham Satish Babar Department of Civil Engineering 2016-17
  2. 2. Contents - 2  Introduction  Components of a Joints System  Bone  Component of Bone  Load deformation  Comparison Between Ligaments and Tendons  Ligaments  Structures  Function  Mechanical Behavior  Tendon  Structures  Function  Mechanical Behavior  Conclusion
  3. 3. Introduction - 3  Behaviour of Structure is very similar to behaviour of Human Body structure  The forces which affecting the behaviour of structures in such manner same forces are affecting on human body structure, but intensity is different  Performance of joints in structure are same as performance of joints in human body  Stiffness to human body structure is provided by Ligaments and Tendons
  4. 4. 4
  5. 5. Joints 5  Ball & Socket  Pivot  Saddle  Hinge  Elipsoid (Condyloid)  Plane or Gliding – vertebrae
  6. 6. 6  Rigid Link (Bone, Tendon, Ligament)  Joint  Muscle  Neuron  Sensory Receptor Components of a Joint System
  7. 7. Wolff’s Law 7  bone is deposited where needed and resorted where not needed  bone remodels in response to applied stress  Bone hypertrophy occurs in areas where stress and strain are increased.  Bone atrophy occurs in areas where stress and strain are decreased. Bone
  8. 8. 8 Purposes of Bone  Provides mechanical support  Produces red blood cells  Protects internal organs  Provides rigid mechanical links and muscle attachment sites  Facilitates muscle action and body movement  Serves as active ion reservoir for calcium and phosphorus Bone
  9. 9. Composition and Structure of Bone  Consists of cells and an organic extracellular matrix of fibers and ground substance  High content of inorganic materials (mineral salts combined with organic matrix)  Organic component  flexible and resiliant  Inorganic component  hard and rigid  Mineral portion of bone primarily calcium and phosphate (minerals 65-70% of dry weight)  Bone is reservoir for essential minerals (e.g., calcium) 9 Bone
  10. 10. 10 Composition and Structure of Bone  Collagen  Mineral salts embedded in variously oriented protein collagen (strength in various directions) in extracellular matrix  Tough and pliable, resists stretching  95% of extracellular matrix (25-30%) of dry weight of bone Bone
  11. 11. 11 Load Deformation Testing Bone
  12. 12. 12 Load Deformation Curve  B – max. load before deformation  D’ – deformation before structural change  Area under curve is force x distance = work= energy Bone
  13. 13. 13 Properties of Stiffness and Brittle/Ductile •Metal – large plastic region •Virtually no plastic region in glass •Stress-strain curve of bone not linear •Yielding of bone tested in tension caused by debonding of osteons at cement lines and micro fractures Bone
  14. 14. 14 Roles of Ligaments and Tendons in the Body Bone
  15. 15. 15 Muscle Activity Changing Stress Distribution Bone
  16. 16. 16 Relationships of Age to Stress- Strain Characteristics of Bone indirect relation between age and energy absorption Bone
  17. 17. Ligaments and Tendon - 17
  18. 18. Comparison - 18 Ligaments Tendons % of collagen Lower Higher % of ground substance Higher Lower Organization More random Organized Orientation Weaving pattern Long axis direction
  19. 19. Ligaments 19 Ligaments
  20. 20. Structure 20  No molecular bonds between fascicles –  Free to slide relative to each other  Orientations:  Branching & Interwoven  Spirally wound  Parallel  Direct connection between bones  Smaller diameter fibers than in tendons Ligaments
  21. 21. Functions 21  Transmit load from bone to bone  Hold the skeleton together  Flexible but plastic  Provide stability at joints  Maintain joint congruency  Limit freedom of movement  Prevent excessive motion by being a static restraint  Occasionally act as a positional bend/strain sensor  Mediate motions between opposing fibrocartilage surfaces Ligaments
  22. 22. Mechanical Behavior 22 Ligaments
  23. 23. Stress Vs. Strain 23 Ligaments
  24. 24. 24 Tendons Tendons
  25. 25. Structure 25  Long cylindrical structures  Tightly packed longitudinally running collagen fibers  Nuclei and sparse cytoplasm of fibrocytes compressed almost flat between them  Relatively avascular  Slow to heal from trauma injuries Tendons
  26. 26. Function 26  Force transmission between muscle and bone  Sustain high tensile stresses  Conserve substantial muscular energy during locomotion  Energy storage capacity  Enables the muscle belly to be at a convenient distance from joint  Satisfies kinematic and damping requirements Tendons
  27. 27. Function 27  Withstand tensile forces while retaining flexibility Tendons
  28. 28. Structure 28  Orientations: Parallel to direction of tensile force  Larger collagen fibers than in ligaments Tendons
  29. 29. Response to Tensile Forces 29  Highest tensile strength of any soft tissue  Schematic load-elongation curve with 3 distinct regions of response to tensile loading: Tendons
  30. 30. 30 Tendons
  31. 31. Mechanical Properties 31  Greater cross cross-sectional area  Larger loads can be applied prior to failure  Increased tissue strength  Increased Stiffness  Longer tissue fibers  Greater fiber elongation before failure  Decreased tissue stiffness  Unaltered tissue strength Tendons
  32. 32. 32 Tendons
  33. 33. Conclusion - 33  Structural behavior of joints in human body is behave live same exactly as reinforcement concrete sections and materials.  Joints includes Bone, Ligaments and Tendons obey the Hook’s Law.  Material properties of joints are varies with respect to gender and age.
  34. 34. Thank You… 34

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