2. INTRODUCTION TO BIOMATERIALS
• During the last two decades, significant advances
have been made in the development of
biocompatible and biodegradable materials for
medical applications.
• In the biomedical field, the goal is to develop and
characterize artificial materials or, in other words,
“spare parts” for use in the human body to
MEASURE, RESTORE and IMPROVE physical
functions and enhance survival and quality of life.
3. What’s a biomaterial?
• 1980 - Passive and inert point of view
Any substance or drugs, of synthetic or natural origin, which
can be used for any period alone or as part of a system and
that increases or replaces any tissue, organ or function of the
body
• 1990 – Active point of view
Non-living material used in a medical device and
designed to interact with biological systems.
4. Biomaterials
Any substance (other than drugs) or
combination of substances synthetic or natural
in origin, which can be used for any period of
time, as a whole or as a part of a system which
treats, augments, or replaces any tissue,
organ, or function of the body.
5. Classification of biomaterials
First generation: INERT
Do not trigger any reaction in the host: neither rejected nor
recognition “do not bring any good result”
Second generation: BIOACTIVE
Ensure a more stable performance in a long time or for the
period you want
Third generation: BIODEGRADABLE
It can be chemically degraded or decomposed by natural
effectors (weather, soil bacteria, plants, animals)
6. What is a biocompatible material?
• Synthetic or natural material used in intimate contact
with living tissue (it can be implanted, partially
implanted or totally external).
• Biocompatible materials are intended to interface with
biological system to EVALUATE, TREAT, AUGMENT or
REPLACE any tissue, organ or function of the body.
• A biocompatible device must be fabricated from
materials that will not elicit an adverse biological
response
7. First Generation Implants
“ad hoc” implants
Specified by physicians using common and
borrowed materials
Most successes were accidental rather than by
design
Examples — First Generation Implants
Gold fillings, wooden teeth, PMMA (Polymethyl methacrylate)_
dental prosthesis
Steel, gold etc., for bone plates
Glass for eyes and other body parts
9. Second generation implants
Engineered implants using common and borrowed materials
Developed through collaborations of physicians and engineers
Built on first generation experiences
Used advances in materials science (from other fields)
Titanium alloy dental and orthopedic implants
Cobalt-chromium- molybdenum orthopedic implants
UHMW (Ultra High Molecular Weight) polyethylene bearing
surfaces for total joint replacements, Heart valves, and pacemakers
Examples — Second generation implants
11. Third generation implants
Bioengineered implants using bioengineered materials.
Few examples on the market.
Some modified and new polymeric devices.
Many under development.
Example - Third generation implants
Tissue engineered implants designed to regrow rather than replace
tissues.
Integra Life Sciences artificial skin.
Genzyme cartilage cell procedure.
Some resorbable bone repair cements
Genetically engineered “biological” components (Genetics Institute
and Creative Biomolecules BMPs - Bone morphogenetic proteins )
14. Biocompatibility
Biocompatibility: the ability of a material to
perform with an appropriate host response in a
specific application
Host Response: the response of the host
organism (local and systemic) to the implanted
material or device.
Arises from differences between living and non-
living materials
15. Mechanical Properties of Metals
How do metals respond to external loads?
Stress and Strain
• Tension
• Compression
• Shear
• Torsion
Elastic deformation
Plastic Deformation
• Yield Strength
• Tensile Strength
• Ductility
• Toughness
• Hardness
16. Stress-Strain Behavior
Elastic deformation
• Reversible: when the stress is
removed, the material returns
to the dimension it had before
the loading.
• Usually strains are small (except
for the case of plastics).
Plastic deformation
• Irreversible: when the stress is
removed, the material does not
return to its previous
dimension.
17. Viscoelasticity
Definition: time-dependent material behavior
where the stress response of that material
depends on both the strain applied and the
strain rate at which it was applied!
Examples
• biological materials
• polymer plastics
• metals at high temperatures
18. Elastic versus viscoelastic behaviors
For a constant applied strain
• An elastic material has a
unique material response
• A viscoelastic material has
infinite material responses
depending on the strain-
rate
19. Host Reactions to Biomaterials
• Effect of the Implant on the Host
• Local
– Blood material interactions
• Protein adsorption
• Coagulation
• Platelet adhesion, activation, release
• Leukocyte adhesion, activation
• Hemolysis
– Toxicity
20. Effect of the Host on the Implant
• Physical – mechanical effects
– Abrasive wear
– Fatigue
– Stress corrosion, cracking
– Corrosion
– Degeneration and dissolution
• Biological effects
– Absorption of substances from tissues
– Enzymatic degradation
– Calcification
21. Types of Metallic Implants
• Stainless steel
• Cobalt Based Alloys
• Titanium Alloys
22. Total Hip Replacement
• A prosthetic hip that is implanted in a similar fashion as
is done in people.
• It replaces the painful arthritic joint.
• The modular prosthetic hip replacement system used
today has three components – the femoral stem, the
femoral head, and the acetabulum.
• Each component has multiple sizes which allow for a
custom fit.
• The components are made of cobalt chrome stainless
steel and ultra high molecular weight polyethylene.
Cementless and cemented prosthesis systems are
available.
23. Common Causes of Hip Pain and Loss
of Hip Mobility
Osteoarthritis
• Usually occurs after age
50 and often in an
individual with a family
history of arthritis. In this
form of the disease, the
articular cartilage
cushioning the bones of
the hip wears away. The
bones then rub against
each other, causing hip
pain and stiffness.
24. Operation
Removing the Femoral Head
• Once the hip joint is
entered, the femoral
head is dislocated
from the acetabulum.
• Then the femoral head
is removed by cutting
through the femoral
neck with a power
saw.
25. Reaming the Acetabulum
• After the femoral head is
removed, the cartilage is
removed from the
acetabulum using a
power drill and a special
reamer.
• The reamer forms the
bone in a hemispherical
shape to exactly fit the
metal shell of the
acetabular component.
26. Inserting the Acetabular Component
• A trial component, which is
an exact duplicate of your
hip prosthesis, is used to
ensure that the joint will be
the right size and fit for the
client.
• Once the right size and
shape is determined for the
acetabulum, the acetabular
component is inserted into
place.
27. Preparing the Femoral Canal
• To begin replacing the femoral
head, special rasps are used to
shape and scrape out femur to
the exact shape of the metal
stem of the femoral
component.
• Once again, a trial component
is used to ensure the correct
size and shape. The surgeon
will also test the movement of
the hip joint.
28. Inserting Femoral Stem
• Once the size and
shape of the canal
exactly fit the
femoral component,
the stem is inserted
into the femoral
canal.
29. Attaching the Femoral Head
• The metal ball that
replaces the femoral
head is attached to
the femoral stem.
30. The Completed Hip Replacement
• Client now has a new
weight bearing surface to
replace the affected hip.
• Before the incision is
closed, an x-ray is made to
ensure new prosthesis is
in the correct position.
31. Treatment by Kinesiologist
-Early Postoperative Exercises-
• Regular exercises to restore your normal hip motion
and strength and a gradual return to everyday
activties.
• Exercise 20 to 30 minutes a day divided into 3
sections.
• Increase circulation to the legs and feet to prevent
blood clots
• Strengthen muscles
• Improve hip movement
32. Artificial heart valve
• An artificial heart valve is a device implanted
in the heart of a patient with heart valvular
disease. When one of the four heart valves
malfunctions, the medical choice may be to
replace the natural valve with an artificial
valve. This requires open-heart surgery.
33. Types of heart valve prostheses
• There are two main types of artificial heart valves: the
mechanical and the biological valves.
• Mechanical heart valves
– Percutaneous implantation
• Stent framed
• Not framed
– Sternotomy/Thoracotomy implantation
• Ball and cage
• Tilting disk
• Bi-leaflet
• Tri-leaflet
• Biological heart valves
– Allograft/isograft
– Xenograft
35. Design challenges of heart valve
prostheses
• A replaceable model of Cardiac
Biological Valve Prosthesis.
• Thrombogenesis /
haemocompatibility
– Mechanisms:
• Forward and backward
flow shear
• Static leakage shear
• Presence of foreign
material (i.e. intrinsic
coagulation cascade)
• Cellular maceration
• Valve-tissue interaction
• Wear
• Blockage
• Getting stuck
• Dynamic responsiveness
• Failure safety
• Valve orifice to anatomical orifice
ratio
• Trans-valvular pressure gradient
• Minimal leakages
• Replaceable Models of Biological
Valves
36. Artificial limb
• An artificial limb is a type of prosthesis that
replaces a missing extremity, such as arms or
legs. The type of artificial limb used is
determined largely by the extent of an
amputation or loss and location of the missing
extremity. Artificial limbs may be needed for a
variety of reasons, including disease,
accidents, and congenital defects.
37. Lower Limb Prosthesis
Components of the Prosthesis
• Socket- Forms the connection
between the residual limb and
the prosthesis.
• Sleeve- Provides suction
suspension for prosthesis.
• Shank (pylon)- Transfers weight
from socket to the foot-ankle.
• Foot-ankle- Absorbs shock and
impact and provides stability.
38. Dental implant
• A dental implant is an artificial tooth root
replacement and is used in prosthetic
dentistry to support restorations that
resemble a tooth or group of teeth. There are
several types of dental implants. The major
classifications are divided into Osseo
integrated implant and the fibro integrated
implant. Earlier implants, such as the sub
periosteal implant and the blade implant were
usually fibro integrated
39. WHAT IS A DENTAL IMPLANT?
Dental implant is an artificial titanium fixture
(similar to those used in orthopedics)
which is placed surgically into the jaw bone to
substitute for a missing tooth and its root(s).
40. FUTURE WORK
Comparison of different implant designs in
terms of stress distribution in the bone due to
occlusal loads.
Modeling non-homogenous bone material
properties by incorporating with CT scan data.
Comparison of different implant-abutment
interfaces
