Biocompatibility Flashcards
What is biocompatibility?
The ability of a material to perform with an appropriate host response in a specific application
Problems of equating inertness with biocompatibility
- No material is completely inert due to impurities or additives (ex: plasticizers)
- Inert material will never truly incorporate (need to stimulate tissues for long term performance)
- Interfacial relations will usually take place anyways
Examples of inert biomaterials
Stainless steel titanium noble metals alumina polyethylene
Things that your body environment contains
Anions cations organic substances dissolved oxygen chloride
pH of body
7.4
Inflammation - 4
Infections - 9
Temperature of body (Celsius)
37
can range from 10 to 50 depending on area of body though
How can protein adsorption control host response?
Plasma protein creates layer on surface of biomaterial through adsorption and desorption
Cell behaviour near material depends on these interactions, changing host response
Effect of material on local tissue
Toxicity Inflammation Healing modification Blood material interactions Infection Tumorigenesis
Effects of environment on materials: Physical-mechanical
Wear
Fatigue
Corrosion
Biological effects of environment on materials
Tissue absorption of implant components
Enzymatic degradation
Calcification
Systemic interactions of biomaterials
Embolyzation
Infection
Elevation of implant elements in blood
Lymphatic particle transport
Device patient complications
Thrombosis and thromboembolism
Infection
Adverse local tissue reaction
Adverse systemic effect
Host response to synthetic materials/foreign bodies
Synthetic materials don’t generate a specific response (unlike organ transplant for example)
Tissue derived biomaterial may elicit response including antibodies
Non-specific inflammatory response/ Foreign body response (attempted phagocytosis by macrophages)
Inflammatory response and wound healing
Insertion process of material produces acute inflammatory response (body’s defence to injury)
In longer term, scar tissue of fibrous collages and fibroblastic cells appears around implant
Negatively active materials
Material will continuously stimulate the inflammation
May lead to increased fibrosis and extensive casing
May produce active chronic inflammation
What balance needs to be struck for a material to be biocompatible?
A balance between inflammation and repair.
Physical modifications to improve tissue interaction
Roughness or porosity
Increases mechanical bonding
Chemical modifications to improve tissue interaction
Adding:
Groups to surface that stimulate adhesion (ex calcium phosphates to bone)
Biodegradable component to encourage tissue healing and replacement
Examples of surface treatments
CpTi fibre metal coating on Ti alloy THA stem
Titanium plasma spray on oral implants
Should blood material interactions be avoided? How are they controlled?
Any interaction with blood or implants should be avoided
Mayor approach to control thrombosis with cardiovascular devices is through anticoagulants
Thrombogenicity
Induction of blood clot formation
Thrombotic/ Blood material interactions
- Plasma protein deposition on foreign material exposed to blood
- Adhesion of platelets and white blood cells at surface
- Bulk fibrin formation (coagulation)
How many implants fail due to infections, and why?
5-10%
They are often resistant to antibiotics and host defences
They increase chance of infection, since micro organisms get access to deeper tissue during implantation
Early infections sources
airborne sources
non sterile surgical techniques
wound infections
