Lecture 25: Introduction to bioengineering and physiology Flashcards
SAFETY
*The patient or user of a
medical device is safe
when the device is used
as the manufacturer
intended
*Includes its chemical,
physical and biological
properties`
EFFICACY
*Effectiveness of the
device or its ability to
fulfil its intended clinical
purpose under
conditions prescribed by
the manufacturer
Safety testing considerations (Biocompatability)
The device materials should not, either directly or through the
release of their material constituents:
* produce adverse local or systemic effects
* be carcinogenic
* produce adverse reproductive and/or developmental
effects
*unless it can be determined that the benefits of the use of
that material outweigh the risks associated with an adverse
biological response.
Local vs Systemic
*Host response is the local and
systemic response (other than the
intended therapeutic response) of
living systems to the material
*Local (at the site of the device)- eg.
Inflammation, irritation, contact
allergy, local infection
*Systemic (remote from the site of
the device, distributed systemically)-
anaphylactic response, sepsis
Defining Biocompatibility – Key Milestones
- Biocompatibility
is understood as
situation specific
*Does it do as
intended – and is
it tolerable to the
patient? - Multiple factors
at play.
Q: What is meant by “biomaterial roughness” in implants?
A: Biomaterial roughness refers to the texture of an implant’s surface, which can be macro (rough to touch, better for bone growth/fusion) or micro/nanostructured (important for cell interactions).
Q: How does roughness affect bone and vascular implants differently?
A: For bone implants, roughness improves bone growth and fusion.
==> a rough surface encourages bone cell attachment and growth. This process is known as osseointegration, where the bone actually fuses with the implant. The tiny irregularities on a rough surface create more contact points for bone cells, allowing them to anchor themselves and eventually form a stable, mineralized layer on the implant.
vascular implants benefit from smoother surfaces to reduce friction and complications.
==>otherwise could cause platelets to adhere to the surface, potentially leading to blood clots (thrombosis and impact blood flow
Q: What is tensile strength, and why is it important in biomaterials?
A: Tensile strength measures a material’s ability to resist breaking under tension. It is crucial for assessing the durability and elasticity of materials, especially for implants subjected to mechanical forces.
Q: What are the three main metrics for porosity in implants?
A: The three metrics are overall pore size,
=> different pore sizes for infiltration and growth, to properly migrate into implant, frow and form new tissue, integrate more effectively
pore connectedness,
=> high pore connectivity means cells, nutrients and blood vessels are travel throughout, proper vascularisation and distrubtion of nutrients and oxygen for survival, growth and healing process
and porosity (volume of air vs. solid material),
=> high can allow cells to colonise but too high porosity could weaken structual integrity of implant, balance for strength and space for cell and tiusse ingrtowth
dall of which influence cell interactions and tissue remodeling.
Q: How does pore size affect biological response in implants?
A: Variations in pore size, such as those seen in silk scaffolds, can drastically alter the biological response, such as tissue integration and healing outcomes.
Q: What is the significance of surface chemistry in biomaterials?
A: Surface chemistry determines the reactivity of the material, affecting properties like charge, wettability, and the ability to bond with bioactive molecules.
Q: What factors should be considered when choosing between permanent and temporary implants?
A: The decision depends on whether the implant needs to last a lifetime or degrade in a controlled fashion. Examples include magnesium stents (2–12 months) and stainless steel stents (permanent).
Q: Define wettability and how it is measured.
A: Wettability refers to how a surface interacts with water, measured by the contact angle. A surface is hydrophilic if the angle is less than 90° and hydrophobic if greater than 90°.
Q: What are the key material properties important for biomaterial design?
A: The six key properties include tensile strength, roughness, porosity, surface chemistry, degradation behavior, and wettability, all tailored to specific implant applications.
Q: Why is biocompatibility context-dependent for medical devices?
A: Biocompatibility depends on the specific material and its intended use in the body. Materials are not universally biocompatible; they are designed for specific applications and locations.
