Introduction to Biomaterials

Surface features have the most significant influence on how well a material interacts with living tissue (biocompatibility).

The inside of a material determines its strength, durability, and how it performs its intended job.

We want to keep the core material strong while changing the surface on a tiny scale (nanometers) to improve its interaction with the body. This can make materials harder, resist rust, and work better with biological systems.

When a material is implanted, proteins immediately coat its surface. Cells then attach to these proteins, influencing how they behave. Controlling these proteins lets us control cellular processes.

By controlling protein adsorption, we can prevent the body's natural rejection of a foreign material, leading to better integration and less inflammation.

A water-repelling surface that minimizes interaction with water, like a raincoat. It's self-cleaning and can bind to proteins strongly.

A water-loving surface that readily interacts with water, allowing for smooth flow. It minimizes friction and blood clotting.

The properties of a material's surface, such as hydrophobicity or hydrophilicity, determine how it interacts with the biological environment in the body.

A phenomenon where a strong implant weakens the surrounding bone because it carries most of the load, preventing the natural bone remodeling process.

A principle stating that bone adapts to the loads placed upon it. Bone will become denser and stronger under higher stress, and weaker under lower stress.

A measure of a material's stiffness or resistance to deformation under tension or compression. A higher Young's modulus indicates a stiffer material.

The maximum stress a material can withstand before it breaks under tension.

A measure of a material's resistance to the growth of cracks. A higher fracture toughness indicates a material that can withstand cracks better.

The amount of deformation a material undergoes before breaking under tension. A higher elongation at break indicates a more ductile material.

The maximum stress a material can withstand before it breaks under compression.

The weakening of a material under repeated loading, even if the load is below the material's yield strength. It can lead to cracks and eventual failure.

A fracture caused by fatigue, typically occurring at a stress level below the material's ultimate tensile strength.

A type of fatigue failure caused by the combination of cyclic stress and friction between moving components.

A type of fatigue failure caused by the combination of cyclic stress and corrosion.

The gradual loss of material due to friction. Can lead to device loosening and particle generation, potentially causing inflammation.

The loosening of an implant due to wear debris generating an inflammatory response, leading to bone resorption and implant failure.

A measure of a material's resistance to indentation. A hard material is resistant to wear and scratching.

Testing performed outside of a living organism, typically in a laboratory setting. This can include cell culture assays or material characterization tests.

Polymer degradation starting from the exterior surface, often caused by factors like water erosion.

Polymer degradation occurring evenly throughout the entire material, leading to a faster decrease in strength over time.

A type of ceramic material used in biomaterials that forms a strong bond with bone tissue.

A lightweight, biocompatible metal used in biodegradable implants. It degrades rapidly, making it suitable for temporary applications.

Devices with low risk, often used externally like bandages, gloves, and stethoscopes.

Devices with moderate risk, including those that come in contact with bodily fluids like blood pressure cuffs and syringes.

Devices with high risk, typically those implanted in the body like pacemakers and stents.

A pathway for FDA approval where a manufacturer demonstrates substantial equivalence to an existing, safe, and effective device.

An FDA decision indicating a new device is as safe and effective as a previously approved similar device.

A rigorous FDA pathway for class III devices, requiring extensive testing and demonstration of safety and effectiveness.

An FDA pathway for devices that are not substantially equivalent to existing devices, but offer a benefit and have moderate risk.

Information collected on recalls of medical devices, providing insight into potential issues and safety concerns.

A database of individual reports on medical devices, providing valuable information for safety monitoring and risk management.

Connective tissue that connects muscles to bones, enabling movement and force transmission.

Connective tissue that connects bones to bones, providing stability and limiting excessive joint movement.

A type of arthritis that occurs when the protective cartilage that cushions the ends of your bones wears down over time. This causes pain, stiffness, and swelling in the joint.

Joints

Collagen, proteoglycan, water, elastin, and hydroxyapatite (bone only)

The dense, hard outer layer of bone that makes up about 80% of total bone mass. It has a low porosity, meaning it has fewer spaces within it.

The spongy, inner layer of bone that is more porous than cortical bone. It is more actively involved in remodeling.

Cells that break down bone tissue, removing old or damaged bone.

Cells that create new bone tissue, building and repairing bone.

Mature bone cells that maintain bone tissue and help regulate bone remodeling.

The most flexible type of cartilage, found in the ear, auditory tube, and larynx.

The second most flexible type of cartilage, found in articular cartilage in joints, the nose, and lungs.

The least flexible type of cartilage, found in the annulus fibrosus of discs, between pubic bones, and other areas that need to resist tension and compression.

The soft, gelatinous center of the intervertebral disc that helps absorb shock and maintain the disc's height.

The tough, fibrous outer ring of the intervertebral disc that encases the nucleus pulposus and resists multi-axial loading.

A thin layer of hyaline cartilage that separates the intervertebral disc from the vertebral body and allows for nutrient transport.

Screws, plates, pins, wires, rods, nails, suture anchors, spinal cages, and joint replacements.

A material utilized in medicine to support, enhance, or replace damaged tissue or a biological function. It's biocompatible, meaning it doesn't harm the body, and can be natural or synthetic.

A biomaterial's ability to not cause harm to the host body. This includes being non-toxic, non-allergenic, non-thrombogenic, non-carcinogenic, non-mutagenic, and non-inflammatory.

A biomaterial can (1) hurt you, (2) dissolve, (3) be surrounded by a protective layer, or (4) integrate with tissue.

Metals composed of metallic elements with small amounts of nonmetals, commonly used in medical implants due to their strength and resistance to fatigue. Examples include titanium, stainless steel, and cobalt-chromium.

Pros: strong, resistant to fatigue, ductile, easily sterilized. Cons: prone to stress shielding, corrosion, and wear.

When an implant carries the load, preventing the surrounding tissue from working and potentially weakening it.

Inorganic compounds of metallic and nonmetallic elements, known for their strength, chemical inertness, and bioactivity, commonly used for dental and hip implants.

Pros: strong, chemically inert, high compressive strength, biodegradable or bioactive. Cons: hard to manufacture, brittle, prone to fracture, can loosen, only have compressive strength.

Long chains of molecules with a carbon backbone, known for their ease of manufacture, moldability, and biodegradability, commonly used for implants and drug delivery.

Pros: easy to manufacture and modify, can be bendable and biodegradable. Cons: poor strength, prone to wear and tear.

The immune response to an implanted device, leading to encapsulation by scar tissue, which can affect implant function.

A natural immune response to injury, characterized by redness, swelling, heat, and pain, which can be acute (immediate) or chronic (long-term).

Blood-material interaction that triggers blood clotting, which can be caused by the material or surgery.

A material designed to degrade and be replaced by natural tissue over time, often used for temporary implants or scaffolds.

Biomaterials have a wide range of applications, including medical implants, promoting healing, regenerating tissues, biosensing, and drug delivery systems.