Title:

"Progress in Creating Bioactive, Patient Specific, Resorbable, Load Supporting Orthopedic Constructs with Magnesium Alloys using Additive Manufacturing

 

ABSTRACT:

 

Regenerative orthopedic medicine is presently under development, poised to provide the next generation of medical care.  This method uses the natural healing processes of the body with autologous tissues to create a living and functional replacement for diseased, defective, or injured tissues. This option of using a bioactive material to stimulate the creation as well as transform into the natural replacement tissue is a monumental shift from the current treatment platforms, where a non-degradable orthopedic implant is created from poorly matched bioinert materials.  Because of these limited material choices and the extended implanted timeframes these current implants can lead to additional trauma and future complications for the patients, requiring major surgical intervention. 

To mitigate these complications and allow regenerative orthopedic medicine to become fully realized, an option that allows regenerative tissue engineering for critical-sized defects exploiting a bioresorbable, load bearing, patient-specific, and bioactive construct is required. Current technologies offer a partial solution to this requirement by using three-dimensional images of the injury or defect site and translating them through multiple steps into a customized implant design. This design is further optimized for biocompatibility allowing accelerated osteointegration while creating a model that is often too structurally complex for conventional manufacturing methods, making additive manufacturing (AM) imperative. 

 Even though the generation of biomimetic structures is possible, the list of AM-capable material to produce these structures are inadequate. The current list of materials does not promote osteogenesis or allow optimal degradation rates for the resorption into the body once the healing has been finalized. The solution to these inadequate materials is to include the use of bioactive and bioresorbable magnesium (Mg) alloys.  These materials were researched extensively since 2008 for optimal biocompatibility, however, these alloys still maintain many of the inherent problems of Mg including the high reactivity and affinity to oxygen. The resulting thick and non-passivating oxide layer combined with the high vapor pressure of Mg prevents easy integration with most AM methods. 

To offer a solution to these problems and further the development of mineralized tissue engineering within regenerative orthopedic medicine, this research aims to create a method of producing AM scaffolds using biocompatible and bioresorbable Mg alloys.  For this to be feasible, the intransigent oxide layer currently preventing the generation of Mg-based AM structures having full density needs to be removed. This item was proved possible within early investigations utilizing aggressive surface finishing procedures and excessive particle plastic deformations. Combining those procedures with a few obscure AM processes allowed the creation of simple Mg-based structures, proving the concept, and moving closer to the goal of an AM method for Mg alloys.

Optimizing these structures through process advancements allowed the identification of several discrete manufacturing steps, which when combined, created a hybrid AM approach for generating the required dense Mg-based structures. These processes are currently being modified under the current research efforts allowing for increased performance in the strength, corrosion rates, and microstructures aimed at matching or exceeding those possible with conventional AM albeit for biocompatible Mg alloys. Capitalizing on these results, future structures created from this process will be investigated for their in-vitro corrosion performance and in-vivo response within suitable animal models, advancing the field of regenerative orthopedic medicine.

 

 

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Link: https://teams.microsoft.com/l/meetup-join/19%3ameeting_MTU5ZWU5MDEtNzQwYy00ZTQyLWIwODMtMDk2MjYzNDhlMTdj%40thread.v2/0?context=%7b%22Tid%22%3a%229ef9f489-e0a0-4eeb-87cc-3a526112fd0d%22%2c%22Oid%22%3a%22ae813229-dbd7-452d-98e9-f7d922028115%22%7d

Passcode: wfSxM3

Meeting ID: 273 156 168 517

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