biomaterials used for surgery

1. BIOMATERIALS
SUBMITTED TO: BY:
DR. MAHENDRA TANWAR DR. KARAN GOYAL
ASSOCIATE PROF.
VETERINARY SURGERY AND RADIOLOGY

2. BIOMATERIALS
 A biomaterial is "any substance 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". e.g. Sutures, bone plates and
screws, Cardiac pacemaker,
Catheters etc.

3. USES OF BIOMATERIALS
Uses of Biomaterials Example
Replacement of diseased and
damaged part
Artificial hip joint
Assist in healing Sutures, bone plates and screws
Improve function Cardiac pacemaker, intra-ocular lens
Aid to diagnosis Probes and catheters
Aid to treatment Catheters

4. IDEAL IMPLANT CHARACTERISTICS
 Complete biological inertness
 Sufficient strength to hold during healing
 Good handling characteristics
 Easily sterilizable, Non allergic
 Non corrosive, Non toxic
 Non carcinogenic, Non teratogenic
 It should be inexpensive

5. BIOCOMPATIBILITY AND HOST RESPONCE
 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.
Biocompatibility evaluation include evaluation for toxicological effects and blood
compatibility.
Toxicity of the material is estimated on the basis of chemical constituents and both in
vitro and in vivo testing.
Materials with good blood compatibility are those which do not denature plasma
proteins, induce thrombus formation or damage blood elements.

6. TISSUE RESPONSE TO IMPLANT MATERIALS
 Local response
 Systemic response
Four types of responses may occur:
 Minimal response: in it a thin layer of fibrous tissue is formed adjacent to the implant.
 Chemically induced response: in it an acute mild inflammatory response occurs or a chronic
inflammatory response develops.
 Physically induced response: it is an inflammatory response to particulate material or to implant
movement in conjugation with shape or surface roughness.
 Necrosis.

7. CORROSION
 It is a term which specifically characterizes the chemical reactivity of
metals and alloys.
Reasons:
 If the composition of the elements in the metal is incorrect.
 If incorrect metallurgical conditions of temperature and cooling are used during
formation of the implant
Corrosion occurs by any one of the three processes:
 Ionization
 Oxidation
 hydroxylation

8. Most modern orthopedic implants are resistant to
corrosion either through the chemical formation of
their alloy or through the formation of an oxide film
on their surfaces. Titanium and titanium alloys are
extremely resistant to corrosion because the titanium
dioxide layer formed is extremely insoluble in vivo.
When the oxide layer is disrupted by handling or
implant conformation, it reforms by a process known
as repassivation.

9. SELECTION OF PROPER BIOMATERIAL
The choice of a specific biomedical material is determined by consideration of the
following:
1- A proper specification of the desired function for the material;
2- An accurate characterization of the environment in which it must function, and the
effects that environment will have on the properties of the material;
3- A delineation of the length of time the material must function;

10. IMPLANT FORMS
1. Sutures: these are the materials used to close
the wound. They remain intact until union
occurs and cause minimal tissue reaction.
2. Meshes: surgical meshes are used to repair
diaphragmatic, abdominal and peritoneal
hernias and to close and provide support to
thoracic wall defects after segmental rib
removal.
nonabsorbable meshes are polyester,
polytetrafluoroethylene and polylropylene
meshes. Absorbable meshes are polyglactin 910
and polyglycolic acid meshes.

11. 3. Tubular implants: these are made primarily of
synthetic nonabsorbable polymers and materials
such as silicon rubber and polyvinyl chloride.
These may be coated with other substances to
enhance biocompatibility and improve longevity.

12.  Solid implants: these are mainly made of
ceramics and metal materials. These are
coated with biocompatible coatings to
decrease thrombogenicity or to enhance
bone growth.

13. TYPES OF BIOMATERIALS
1. Organic absorbable materials
2. Synthetic absorbable materials
3. Organic nonabsorbable materials
4. Synthetic nonabsorbable materials
5. Metals
6. Ceramics
7. Adhesive glues
8. Hemostatic agents

14. ORGANIC ABSORBABLE MATERIALS
1. Surgical gut or catgut: it is made from submucosa of sheep
intestine or serosa of bovine intestine. It is approximately 90%
collagen and often cured with chrome salts to increase strength
and decrease absorption rate of suture.it is broken down and
absorbed by phagocytosis.
2. Collagen: it can be purified and extracted from connective tissue
as bovine hide. It is currently available as a haemostatic sponge.
Collagen can be resorbed into the body, is non-toxic and can be
cross-linked with chemicals to make it stronger or to alter its
degradation rate.

15. SYNTHETIC ABSORBABLE POLLYMERS
1. Polyglycolic acid: it is marketed as multifilament suture formed
from filaments of glycolic acid and may be coated or
uncoated. These sutures are not exposed to bladder lumen as
exposure to alkaline urine results in more rapid and
unpredictable absorption.
2. Polyglactin 910 (vicryl): it is available as a multifilament suture
composed of copolymer of lactic and glycolic acids. Its rate of
loss of tensile strength is similar to that of polyglycolic acid
but it is more stable in alkaline urine.

16. 3. Polydioxanone: it is a monofilament synthetic suture absorbed by
hydrolysis. It has more tensile strength and prolonged absorption than
above sutures.
4. polyglyconate: it is a monofilament suture. These absorbable sutures are strongest
of all sutures except stainless steel. These have best knot security of all the
absorbable sutures.
5. Polylactic acid: it forms absorbable orthopedic intramedullary rods and screws for
use in research and clinical surgery. These implants absorb slowly with appreciable
strength loss in 2 to 3 months.

17. ORGANIC NONABSORBABLE MATERIALS
1. Silk: it may be plain or braided and capillary
in nature. It does not cause sever tissue
reaction. It has excellent handling
characteristics and knot security.

18. 2. Cotton: it is less irritating than catgut and silk, stable to sterlisation and has
good knot security. But due to its capillary nature it clings to surgeon’s gloves and it
can spread infection in wound when applied to skin and luminal surfaces.
3. Linen: it is capillary in nature and produces more tissue reaction than cotton and
silk.

19. SYNTHETIC NONABSORBABLE MATERIALS
1. Polyester (decron): it is a synthetic fiber formed of polyethylene terephthalate. It is
most widely used vascular prosthesis used in woven form and is also available as a
braided suture.
2. Polyethylene: It is chemically the simplest of all polymers as a homochain polymer.
It is Stable, Relatively inexpensive and has good general mechanical properties. So
that it has become a versatile biomedical polymer with applications ranging from
catheters to joint-replacement.
3. Polymethyl methacrylate: it is relatively bioinert with little tissue reaction that
results in a fibrous layer surrounding the implant. It is used as a bone cement for
implantation of metal implants.

20. 4. Polytetrafluoroethylene (teflon): it is Hydrophobic, Biologically inert, Non-
biodegradable, Has low friction characteristics. PTFE has many medical uses as
Catheters; Sutures; Uses in reconstructive and cosmetic facial surgery. PTFE has
relatively low wear resistance. Under compression or in solutions where rubbing or
abrasion can occur, it can produce wear particles. These can result in a chronic
inflammatory reaction, an undesirable outcome.
5. Polyurethane: it is used for coating of cardiovascular implants because it has low
thrombogenicity.
6. Polyvinyl chloride: it is an organochloride polymer that is used mainly in cannulas
and catheters.

21. 7. Sillicon rubber: it is an organosilicon polymer
that is highly biocompatible. It is used mainly in
catheters, electric leads and drug release capsules.

22. METALS
The most commonly used metallic implant materials are
stainless steel type 316L, cobalt-chromium alloys and
titanium & its alloys.
1. stainless steel type 316L: it is composed of iron(55-
60%), chromium (17-20%), nickel(10-
14%),molybdenum(2-4%) and carbon. It is used as
surgical suture, surgical staples and orthopedic
implants.

23. 2. cobalt-chromium alloys: these are used as orthopedic
implants and allows the best combination of abrasion
resistance, low corrosion characteristics and high
fatigue strength.
3. titanium & its alloys: titanium is most resistant to
corrosion of metal implants and is most brittle. It is
very expensive and is used as surgical staples and
orthopedic bone plates and screws.

24. CERAMICS
Ceramics are used for the repair and restoration of diseased or damaged parts of the
musculo-skeletal system.
Bio-ceramics may be:
1- Bioinert like Alumina (Al2O3), Zirconia (ZrO2);
2- Resorbable like tri-calcium phosphate (TCP);
3- Bioactive like Hydroxyapatite, bioactive glasses, and glass-ceramics;
4- Porous for tissue in-growth (hydroxyapatite)

25. Type of
Bioceramic
Type of Attachment Example
1. Dense, nonporous, nearly inert ceramics
attach to bone by pressing implant into a
defect (termed Morphology Fixation).
Al2O3
2. For porous inert implants bone ingrowth
occurs, which mechanically attaches the
bone to the material (termed Biological
Fixation)
Certain corals

26. 4. Dense, nonporous, surface-reactive
ceramics and glass-ceramics attach directly
by chemical bonding with the bone (termed
Bioactive Fixation)
Hysdroxyapetite
5. Dense, nonporous (or porous), resorbable
ceramics are designed to be slowly replaced
by bone.
Tricalcium
phosphate, Calcium
phosphate salts

27.  Alumina: High density high purity (>99.5%) alumina (a-Al2O3) was the first
bioceramic widely used clinically. It is used in load-bearing hip prostheses and
dental implants.
 Corals: Several types of coral are promising, with pore-size range s of 40-160mm
and 200-1000mm. After the coral shape is machined, it is fired to drive off CO2
from the limestone.
 Bioactive glass ceramics: they contains specific amounts of SiO2, CaO, and P2O5.

28. ADHESIVES
 Autologous fibrin: it is composed of fibronectin,
thrombin, apoprotin, fibrinogen, factor xlll and
calcium chloride and is obtained by collecting
plasma from the animal before surgery. It is used
for fixation of skin grafts and stabilization of nerve
anastomoses.
 Cyanoacrylates: these polymerize in the presence
of moisture to produce a strong flexible bond.
These are used for closure of skin incisions, tail
docking ear cropping etc.

29. HEMOSTATIC AGENTS
 Absorbable gelatin sponge: it is prepared from
purified gelatin solution. It is supplied as small
gelatin sheets that may be cut to the desired size
and held in place.
 Oxidized regenerated cellulose: produced by
controlled oxidation of regenerated cellulose.

30.  Bone wax: it is a mixture of bee wax, paraffin and isopropyl palmitate. Bone wax
controls bleeding from bone surface by acting as a mechanical barrier.
 Collagen absorbable hemostat: it comes in the form of a sponge like pad.
Absorption occurs by phagocytosis and monocytic enzymatic degradation.