Key Properties The main property required of a biomaterial is biocompatible –the immune system doesn’t recognise the material as foreign.
Metal Alloys Metal alloys are used for load bearing applications and must have sufficient fatigue strength to endure the rigors of daily activity eg walking, chewing etc.
What is a Metal Alloy? Metal alloys are mixtures of two or more metals.. A stent made of nitinol.
Nitinol alloy of nickel and titanium shape memory alloy with superelastic properties (similar to that of bone) Applications include stents, heart valve tools, bone anchors, staples.
Titanium Alloy Titanium alloys- light, strong and totally bio-compatible. More than 1000 tonnes of titanium devices are implanted in patients worldwide every year!
Steel Alloy Stainless steel is an alloy of iron, carbon and chromium. Stainless steel is very strong and resistant to corrosion. Surgeons use screws to fasten cruciate ligaments in the knee. The screws on the right are medical grade stainless steel.
Ceramic Biomaterials generally used for their hardness and wear resistance for applications such as articulating surfaces in joints and in teeth as well as bone bonding surfaces in implants.
Plastics Plastics are usually used for their flexibility and stability, but have also been used for low friction articulating surfaces.
What is Plastic? Plastics are polymers. many are malleable, having the property of plasticity
Polymers A polymer is a compound consisting of large molecules made up a series of repeated monomers Example- Cellulose is made by plant cells (their cell walls) Cellulose (a polymer) is made of repeating units of glucose (a monomer)
Uses of Collagen Active materials provide a framework to encourage bonding to surrounding tissue
Orthopaedic Applications Metallic, ceramic and polymeric biomaterials are used in orthopaedic applications. Metallic materials are normally used for load bearing members such as pins and plates and femoral stems etc. Ceramics such as alumina and zirconia are used for wear applications in joint replacements, while hydroxyapatite is used for bone bonding applications to assist implant integration. Polymers such as ultra high molecular weight polyethylene are used as articulating surfaces against ceramic components in joint replacements. Porous alumina has also been used as a bone spacer to replace large sections of bone which have had to be removed due to disease. Dental Applications Metallic biomaterials have been used as pins for anchoring tooth implants and as parts of orthodontic devices. Ceramics have found uses as tooth implants including alumina and dental porcelains. Hydroxyapatite has been used for coatings on metallic pins and to fill large bone voids resulting from disease or trauma. Polymers, have are also orthodontic devices such as plates and dentures Cardiovascular Applications Many different biomaterials are used in cardiovascular applications depending on the specific application and the design. For instance, carbon in heart valves and polyurethanes for pace maker leads Cosmetic Surgery Materials such as silicones have been used in cosmetic surgery for applications such as breast augmentation.