overview on connective tissue.

1. TISSUE
BIOMECANICS
- D R . M A N S I KOT E C H A ( B P T )

2. C O N N E C T I V E T I S S U E I S
C H A R A C T E R I Z E D B Y W I D E LY
D I S P E R S E D C E L L S A N D A
L A R G E V O L U M E O F
E X T R A C E L L U L A R M AT R I X
1)Cells :-fibroblast is the basic cell of most connective
tissues; it produces the extracellular matrix. Depending
on its mechanical and physiological it specialize to
becomechondroblasts(cartilage),tenoblasts (tendon), or
osteoblasts (bone); thesecells are called fibrocytes,
chondrocytes, and osteocytes.
2) Fibers :- aka fibrilar component of extracellular matrix
. It is mostly made up of collagen and elastin.
Collagen has tensile strength similar to steel and is
responsible for functional integrity of connective tissue
structures and resistance to tensile forces.
Elastin is highly elastic protein allows tissue to resume
their shape after stretching or contracting
3) Ground substance :- aka inyerfibrillar component of
extracellular fluid contains water and proteins, primarily
glycoproteins and proteoglycans (PGs)
Its helps development, movement and proliferation of
tissue.

3. TISSUE BIOMECHANICS .
• It is a term used to analyse biomaterials(bone,cartilage,tendons,etc.) or biofluids(blood)
i.e. connective tissue mechanically.
• Biomaterials can be categorized into two:-
• Eg bone
• Theory of elasticity
Hard tissue
• Eg:- Muscle,tendon,cartilage,ligament
• Theory of stress and strain .
Soft tissue

4. STRUCTURE AND COMPOSITION OF
BONE.
COMPOSITION OF BONE STRUCTURE OF BONE

5. WOLFF'S LAW
• states that bone will adapt to the loads under which it is placed. If loading on a
particular bone increases, the bone will remodel itself over time to become stronger to
resist that loading. The internal architecture of the trabeculae undergoes adaptive
changes, followed by secondary changes to the external cortical portion of the
bone, perhaps becoming thicker as a result.
• The inverse is true as well: if the loading on a bone decreases, the bone will become
less dense and weaker due to the lack of the stimulus required for
continued remodeling. This reduction in bone density (osteopenia) is known as stress
shielding .

6. STRUCTURE OF CARTILAGE

7. STRUCTURE OF TENDON
TENDON HAVE A HIERARCHICAL
STRUCTURE
THERE ARE FOUR ZONES, FROM PURE TENDON
(ZONE 1) TO BONE (ZONE 4). THE TENDON
GRADUALLY TRANSITIONS FROM
FIBROCARTIL AGE(ZONE 2) TO MINERALIZED
F IBROCARTIL AGE ( ZONE 3 ).

8. GENERAL PROPERTIES
OF CONNECTIVE TISSUE
• Connective tissues are called heterogeneous because they are composed of a mixture
of solid and semisolid components
• Connective tissues change their structure and/or composition (and thus their function)
in response to applied force
• Tendon responds to changes in applied compression forces by increasing the amount
of GAGs and PGs it contains and by changing the type of GAG (from dermatan sulfate
to chondroitin sulfate).
• Increases in tensile forces cause increases in type I collagen in ligaments and tendons.
• The remarkable ability of connective tissues to respond to load alterations is often
referred to as the SAID principle (specific adaptation to imposed demand).

9. LOA D – D E F O E M I T Y
C U R V E
Load-deformation curve for a
connective tissue tested in tension.
Initially,
the crimp straightens with little force
(toe
region). Then, collagen fibers are
stretched as
the elastic region begins at A. After the
elastic
region ends (B), further force
application
causes a residual change in tissue
structure

10. THE YOUNG’S MODULUS (E), OR
MODULUS OF EL ASTICITY
• The modulus of elasticity is a measure of
the material’s stiffness.
• Force applied :- tensile or compressive
• A value for stiffness can be found by
dividing the change in (Δ) stress by the
change in (Δ) strain for any two consecutive
sets of points in the elastic range of the
curve
• The inverse of stiffness is compliance.
• If the slope of the curve is steep and the
modulus of elasticity is high, the material
exhibits high stiffness and low compliance.
If the slope of the curve is gradual and the
modulus of elasticity is low, the material
exhibits low stiffness and a high
SHEAR MODULUS OR MODULUS
OF RIGIDITY(G)
• Modulus of rigidity is the measure of
the rigidity of the body when shear
force is being applied.
• Force applied :- shear
• A value for rigidity can
• be found by dividing the change in (Δ)
shear stress by the change in (Δ) shear
strain for any two consecutive sets of
points in the elastic range of the
curve.

11. LOAD DEFORMATION AND STRESS-
STRAIN CURVES

12. • (0 to A) toe region.
• Very little is required to deform the tissue as the wavy crimp pattern is
straightened out.
• a minimal amount of force produces a relatively large amount of
deformation (elongation); stress is low, and the strain is typically in the
1% to 2% range.
• Clinical examples involving the toe region include tests for ligament
integrity (for noninjured ligaments) and the slack taken up in a tendon
by its attached muscle before the force is transmitted to a bone.

13. • (A to B) elastic region.
• elongation (strain) has a linear relationship with stress. Each additional unit of applied
force creates an equal stress and strain in the tissue.
• In this region of the curve, collagen fibrils are being stretched and are resisting the
applied force
• When the load is removed, the ligament or tendon will return to its prestressed
dimensions, although this return will take some time time. This level of loading
includes the stresses and strains that occur with normal activities and typically extends
to about 4% strain.

14. • (B to C) the plastic region.
• The failure of collagen fibers (microfailure) begins, and the ligament or tendon is no
longer capable of returning to its original length after the force is removed
• Clinical examples include grade I and II ligament sprains and tendon strains. Recovery
after this level of loading requires considerable time because it involves aspects of
healing such as synthesis of new tissue and cross-linking of collagen molecules.

15. • From point C and further.
• If force continues to be applied beyond the plastic region, the remaining collagen
fibrils experience increased stress and rapidly rupture sequentially, creating overt
failure (macrofailure) of the tissue.
• In the case of a ligament or tendon, if the failure occurs in the middle of the structure
through a disruption of the connective tissue fibers, it is called a rupture.
• If the failure occurs at the bony attachment of the ligament or tendon, it is called an
avulsion.
• When failure occurs within bony tissue, it is called a fracture.
• Slow loading rates tend to create avulsions or fractures, whereas fast loading rates
create midsubstance tears.

16. THANK-YOU
R E F E R A N C E : - J O I N T S T R U C T U R E A N D F U N C T I O N -
PA M E L A & N O R K I N S , ( 5 T H E D I T I O N )