Biomaterials

Biomaterials Lecture #4 Biomaterials “…systemically and pharmacologically inert substance designed for implantation within or incorporation with living systems.” (Clemson University Advisory Board for Biomaterials) Problem Area Examples Replace diseased or damaged part Artificial hip joint, kidney dialysis machine Assist in healing Sutures, bone plate, screws Improve function Cardiac pacemaker, intraocular lens Correct functional abnormality Cardiac pacemaker Correct cosmetic problem Augmentation mammoplasty, chin augmentation Aid to diagnosis Probes and catheters Aid to treatment Catheters, drains Biomaterials in Organs Organ Examples Heart Pacemaker, valves, total heart replacement Lung Oxygenator machine Eye Contact lens, intraocular lens Ear Artificial stapes, cochlea implant Bone Bone plate, hip/knee replacement Kidney Dialysis machine Bladder Catheter and stent Materials Materials Advantages Disadvantages Examples Polymers (nylon, Resilient Not strong Sutures, blood vessels, silicone rubber, Easy to fabricate Deforms with time hip & knee bearing polyester, PTFE, etc.) (creep), may degrade surfaces Metals (Ti and alloys, Strong, tough, ductile May corrode, dense, Joint replacement, Co-Cr alloys, stainless difficult to fabricate bone plate & screws, steels, Au, Ag, Pt, etc.) dental root implants, pacer and suture wires Ceramics (aluminum Very biocompatible, Brittle, not resilient, Dental, femoral head of oxide, calcium inert, strong in difficult to fabricate hip implant, coating of phosphates, carbon) compression dental and orthopedic implants Composites (C-C, wire Strong, engineered Difficult to fabricate Joint implants, or fiber reinforced bone prostheses, heart cements) valves Biomaterials Successful use of biomaterials not practical until development of aseptic surgical techniques in 1860s Pathway to infection Joseph Lister (1827 – 1912) Professor of Surgery – Glasgow University Influenced by work of Pasteur – tried to ensure that germs in air did not get into wounds Carbolic acid Got idea from treatment of sewage Louis Pasteur (1822 – 1895) Disease due to “miasma,” bad air French chemist Commissioned to find out why wine sometimes turned to vinegar Determined that there were microorganisms in the air and boiling would kill – Pasteurization Recommended boiling instruments Robert Koch (1843 – 1910) Cholera and tuberculosis Discovered that microbes cause wounds to go septic Different microbes cause different diseases Staining Ignaz Semmelweiss (1818 – 1865) Professor in maternity department @ University of Vienna Childbed fever – “puerperal fever” 16% mortality rate Lower in midwife clinics May 1847 required delivering physicians to wash hands with chlorinated lime water Deaths went from 12.4% to 3% and later 1.2% Early Applications of Biomaterials Sutures Implants Natural fibers, linen, silk Improved with Introduction of infection development of better metl systems Catgut (sheep intestine) Stainless steel absorbable Co-Cr alloys Implants Plastics Skeletal system Acrylics – polymethyl Bone plates – long bone methacrylate (PMMA) fracture WW II – noticed that Poor design fighter pilots wounded by corrosion canopy shards did not have adverse reaction to fragments left in body. Notable Developments Year Investigators Development Late 18th-19th Century Various metallic devices for bone fractures 1860-1870 Lister Aseptic surgical techniques 1886 Hansmann Ni-plated steel bone fracture plate 1893-1912 Lane Steel screws and plates (18/8 Cr/Ni) 1912 Sherman Vanadium steel plates 1924 Zierold Stellites® (CoCrMo alloy) 1926 Lange Introduced 18/8 Mo stainless 1926 Hey-Groves Csrpenter’s screw for femoral neck fracture 1931 Smith-Peterson Stainless screw for femoral neck fracture 1936 Venable, Stuck Vitallium® 19/9 stainless, later CoCr 1938 Wiles First total hip replacement 1939 Burch, Carney Introduced tantalum (Ta) 1946 Rudet and Rudet First biomechanically designed femoral head replacement; first use of acrylic (PMMA) 1940s Dorzee, Franceschetti PMMA for corneal replacements 1947 Cotton Ti and Ti alloys 1952 Voorhees et al. First successful cloth blood vessel 1958 Furman, Robinson First successful direct heart stimulation 1958 Charnley PMMA bone cement 1960 Starr, Edwards First commercial heart valves 1970s Kolff Total heart replacement Historical Background - Sutures Sutures Stainless wire and polymers (nylon, polyester, polypropylene) Use of textiles goes back at least 4000 years during and after WW II Linen (earliest) 1970s Dexron® (polyglycolic Other acid) and Vicryl® (polyglactic Fe wire, Au, Ag, dried gut, acid) resorbable horse hair, strips of hide, Controlled degradation bark fibers, silk, and tendon Staples Up until 1930, catgut and silk Metallic Polymeric Surgical Needles Primary function – carry the Bronze Roman surgical needle, ca. 100 AD suture through the tissues No role in healing, but can prolong operating time and/or cause damage Recorded use as early as 3000 BC Sharpened bones, wood, Modern stainless steel surgical needles thorns used by primitive peoples. Today high strength materials and engineered needles and needle holders Needle holder.

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