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innovations CASTING


Biodegradable Magnesium Could Mean Fewer Surgeries for Patients


O


rthopedic surgeons generally have two imperfect choices for medical implants used in bone operations:


parts produced in a biodegradable ma- terial such as plastic or ceramic that are not strong enough for certain healing procedures or non-biodegradable metal parts (typically titanium or cobalt) that have the required strength but must be surgically removed. One alloy devel- oper says it may have a solution with a nanostructured magnesium alloy tailored to be absorbed into the body. nanoMag LLC, Livonia, Mich.,


a subsidiary of Thixomat Technolo- gies LLC, was awarded new funding from the National Science Founda- tion (NSF) in January to continue its work in developing biomedical implants, which are produced using Thixomat’s proprietary injection mold casting process. According to nanoMAG, the implants dissolve over months as the bone recovers its original strength. Possible orthopedic load-bearing applications and fixation devices include screws, staples, tacks, wire, rods, plates, and 3D shapes for liga- ment fixations, craniofacial implants and small bone implants. State-of-the-art plastic absorb- able implants generally cannot obtain hardness levels suffi cient for structural support and rugged fi xation into a bone. T is limits their use to smaller fi xations or reconstructive surger- ies. Plastics also can lead to an acidic local environment, which slows bone reconstruction, according to Stephen LeBeau, nanoMag president. Current titanium and cobalt implants deliver the required strength and hardness but


are not bio-absorbable. When a metal implant must be removed after the bone heals or a pediatric patient out- grows the implant, a secondary surgical procedure is required. According to nanoMAG, its bio-


absorbable magnesium alloy combines a stiff ness level close to that of bone with bio-absorbable properties. T e alloy’s composition contains elements naturally found in the body and is designed to control the rate of dissolu- tion. As a result, the implant can sup- ply the necessary temporary structural reinforcement while avoiding the com- plications associated with permanent metal alloy implants, LeBeau said. Animal testing of the material will


be performed in collaboration with the NSF Engineering Research Center for Revolutionizing Metallic Biomateri- als, Greensboro, N.C. T e center will receive $25 million from NSF and the state of North Carolina over the next fi ve years to establish a multi-disciplin- ary research and development opera-


tion for metallic biomaterial implants. nanoMAG plans to provide exper- tise in magnesium alloy design and fabrication to OEM customers, which will then take the product through early animal validation studies, FDA regulatory approval, and ultimately to market and distribution. T e overall market for orthopedic implants is an estimated $37 billion worldwide with $14 billion for recon- struction devices and $4 billion for trauma fi xation devices. Approximately 60% of the market is U.S.-based, and growth is estimated at 12%-13% per year. Strong growth is seen in cranio- facial repairs, including jaw and facial reconstruction, as well as dental im- plants (15%) and small bone implants (12%). T e market size for small bone and craniofacial repairs is estimated to be approximately 1.8 to 2 million procedures per year, with a total value of $4.3 billion. 


For more information, visit www.nanomag.us.


Initial research for bioabsorbable magne- sium implants have centered on screws, but the material’s use could extend to 3D shapes for ligament procedures and cra- niofacial and small bone implants.


Mar/Apr 2012 | METAL CASTING DESIGN & PURCHASING | 55


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