Why is titanium the metal of choice for medical ...

1 Why is titanium the metal of choice for medicalapplications from head to toe?International titanium Association medical DATA SHEETB iocompatibility that s head and shoulders above other materialsBecause it is absolutely inert in the human body, immune to attack from bodily fluids, compatiblewith bone growth, and strong and flexible, titanium is the most biocompatible of all was first used in surgery in the 1950 s and in dentistry a decade earlier, and is nowextensively and routinely accepted by medical professionals as the material of choice forprosthetics, internal fixation, inner body devices and the significant benefits titanium offers patients, surgeons and engineers, use of the metalshould increase in the future, driven by the aging baby boomer generation, the trend towardmore active lifestyles, and the pressure to control health care of the most frequent uses oftitanium is for spinal fusion cages,implants, correction parts and conduction hearing aids areanchored with a titanium devicethat connects to the middle prosthetics can be madefrom titanium ; titanium implantsstabilize soft tissue pegs used to attachfalse eyes and ears; pure titaniumgrid implants provide fixation forinterorbital half of all kneereplacements are made from titaniumincludes surgical devices, dental drills,laser electrodes, stents, marker bands,optical procedure devices, vena cavaclips, needles, staples, blades andforceps, to name just a plates, mesh and acrylic areused in cranioplasty and neurosurgeryto speed operations and recovery andto reduce chances of dental implants act as artificialroots, providing a secure base a full archof teeth, or a single tooth; orthodonticbraces of titanium are stronger, lighterand more biocompatible than heart valves compete with thosemade of tissue.

2 Pacemaker cases andvascular access ports are made of titaniumand nickel- titanium superelastic tubing isused in coronary angioplasty and elbow joint implantsare commonly made of and finger implants are made of nails made from titanium are usedfor reinforcement in lower leg titanium bone plates and mesh thatsupports broken bones are commonly used titanium fixation devices include bone screws,plates, rods, hooks and nails, cable and most common biomedicaluse today of titanium is forhip shape memory alloys areused in medication mini-pumps that flexdue to an electric current that creates aheating/cooling cycle that changes shapeof a rib cages made oftitanium allows a child s rib cageto grow with the is used for urethral stintsto treat urethral titanium ASSOCIATION1871 Folsom Street, Suite 200 Boulder, Colorado 80302-5714 USA(303) 443-7515 Phone(303) 443-4406 International titanium Association accepts no responsibility for either the accuracy or completeness of the information contained herein and, by publishing the same, should not beperceived as making any industry recommendation.

3 Additional information may be available which may have a material effect on the interpretation and use of the information International titanium Association, 10/99 Unique properties make titanium the ultimate biomedical choiceInert to human body fluids: Substantial, regularuse has proven that titanium is completely resistantto body environments, under stress, fatigue and increvice conditions. This is due to its protective oxidefilm, which forms naturally in the presence of eventrace amounts of any form of oxygen. The film ishighly adherent, insoluble and chemically non-transportable, preventing reaction to film also gives titanium its unique soft greyappearance. While titanium may not be as shiny asother metals, it is resistant to abnormally corrosiveseptic : Due to its high dielectric constant, titanium has the property that it can bind to boneand living tissue. Since the implants tissues physicallybond with bone, they last longer than when made ofmaterials that need adhesives.

4 The forces requiredto break the bond are quite , yet light weight: titanium is lighterweight than stainless steel (approximately 56% asdense) yet has a yield strength twice that of stainlesssteel and ultimate tensile strength almost 25%higher. This gives it the highest strength-to-weightratio of any metal suited to medical use. In addition,its density is similar to bone, enabling superior x-ray,MRI and computed tomography : titanium s modulus of elasticity andcoefficient of thermal expansion match those ofhuman bone, reducing the potential for implantfailure. When beta alloyed (as with niobium andzirconium), titanium is used for low modulusapplications; when alpha-beta alloyed (as with, titanium is useful for applications requiring greatermodulus, such as bone : titanium is not susceptible tooutside interference and won t trigger worked: Conventional metal processingtools and techniques can be used to form, machineand join titanium . Workability is comparable tostainless steels and Tungsten Inert Gas welding isreadily performed without a vacuum (for example,to weld a titanium prosthetic vertebra to a titaniumSTORZ fixation plate).)

5 CONTINUING ADVANCES PROMOTE WIDER USE AND LOWER COSTR esearch and development on titanium s medical applications is concentrated on new alloys,production technologies, surface treatments that improve biocompatibility and prevention offretting forging: This technique is being used to form parts that meet strength andrupture elongation specifications, with significant cost savings over conventionally metallurgy: This technology is promising for fabricating titanium alloyed withniobium and tantulum, to reduce : To enhance biocompatibility, titanium can be coated, by plasma spray or chemicalreaction, with hydroxy apatate (a calcium phosphate ceramic). Coatings are also used toimprove wear titanium ALLOYS FOR medical USET itanium is available in commercially pure and alloyed product forms, as prefabricatedcomponents as well as mill products including bar, plate and sheet. Alloying and heattreating yield a wide range of mechanical properties, and it is almost always possible tobalance the requirements of surgeons, who demand full tissue compatibility (wherecommercially pure titanium is the benchmark) with the preferences of medical productdevelopers who prefer stronger alloys (for more economical fabrication).

6 Alloying materialsfavor non-toxic elements including niobium, zirconium, tantalum, molybdenum and tin;nickel, chromium and cobalt, which can be toxic, are avoided. In general, the strongerbeta alloys are used in low modulus applications; alpha-beta alloys are used when a greatermodulus of elasticity is needed (for example bone plate).Commercially Pure Grades 1 - 4: Unalloyed titanium is the most corrosion resistant. Itsmechanical properties, including strength, ductility, formability and weldability vary with smalladditions of oxygen and iron. Grade 1 contains lowest levels of oxygen and iron, prod the mostformable metal , higher grades have progressively greater oxygen contents for higher 6Al-4 Veli (extra low interstitial): Ti6-4, an alpha-beta alloy, has long been used inorthopedic surgery with proven clinical success. The eli grade was developed for improvedfracture toughness and improved cryogenic ductility. Implants (spinal fixation, staples,needles) are a principal : This alpha-beta alloy is used for heart pacemaker electrodes; it is biocompatibleand the porosity of its surface permits good signal : This is an alpha-beta alloy with mechanical properties similar to 6-4, but bettercorrosion resistance.

7 When hot forged, it is possible to attain good economic is also being investigated for casting of dental : This near-beta alloy, used for orthopedic implants, has low modulus andhigh strength, is formable and highly corrosion resistant. It can also be surface hardenedto optimize : This is a beta alloy with higher strength and lower modulus than 6-4 and noaluminum or vanadium. It offers improved long term performance in orthopedic (TMZF): This relatively new alloy has a low modulus, excellent mechanicalproperties, corrosion resistance and formability, good wear and notch fatigue resistance.