Biomechanics

1. 1
Presentation on
“Structural Behavior of
Joints in Human Body”
By:
Shubham Satish Babar
Department of Civil Engineering
2016-17

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. 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

5. Joints
5
 Ball & Socket
 Pivot
 Saddle
 Hinge
 Elipsoid (Condyloid)
 Plane or Gliding –
vertebrae

6. 6
 Rigid Link (Bone, Tendon, Ligament)
 Joint
 Muscle
 Neuron
 Sensory Receptor
Components of a Joint System

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
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. 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
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
Load Deformation Testing
Bone

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
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
Roles of Ligaments and Tendons
in the Body
Bone

15. 15
Muscle Activity Changing Stress
Distribution
Bone

16. 16
Relationships of Age to Stress-
Strain Characteristics of Bone
indirect relation between age and energy absorption
Bone

17. Ligaments and Tendon -
17

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. Ligaments
19
Ligaments

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. 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. Mechanical Behavior
22
Ligaments

23. Stress Vs. Strain
23
Ligaments

24. 24
Tendons
Tendons

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. 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. Function
27
 Withstand tensile forces while retaining flexibility
Tendons

28. Structure
28
 Orientations:
Parallel to direction of tensile force
 Larger collagen fibers than in ligaments
Tendons

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
Tendons

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
Tendons

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. Thank You…
34