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Materials Science in Additive Manufacturing MAM for orthopedic bone plates: An overview

to markedly bolster the microstructural and mechanical integrity, which can be tailored through post-processing,
attributes of Ti6Al4V alloy samples. determines how a bone plate will interact with the
Hybrid manufacturing presents a constellation of biological environment. An optimized surface can reduce
advantages, including elevated efficiency, improved product corrosion, minimize bacterial adhesion, and promote
quality, and a marked reduction in material wastage . Yet, osseointegration, ensuring the long-term success of the
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as a nascent technology, it grapples with hurdles. Limited implant . On the other hand, a compromised surface can
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accessibility to specialized machines, intricate integration have severe repercussions, including implant failure .
demands, and an augmented necessity for rigorous quality Research findings emphasize the nuanced role of post-
assurance stand out as prominent challenges. processing. Jahadakbar et al.’s work on porous nitinol
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In the domain of bone plate manufacturing, the bone fixation plates illustrates the efficacy of chemical
evolution from traditional subtractive methods to polishing in removing unmelted powder residues while
revolutionary AM techniques, and ultimately to hybrid preserving intricate geometries. The scanning electron
approaches, showcases the industry’s relentless pursuit of microscopy analysis of their study specifically found that
innovation. Subtractive manufacturing, while proficient in an etching solution composed of 10% HF, 40% HNO , and
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mass production, often encounters limitations in crafting 50% H O, applied for an effective time of 4 min, was optimal
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patient-specific solutions. AM techniques, especially for removing unmelted powder particles. Such meticulous
PBF, introduce unparalleled flexibility in crafting post-processing is essential, especially when catering to
intricate, customized designs, although with its own set patient-specific needs that require high precision.
of challenges, such as high costs and post-processing Heat treatment plays a pivotal role in refining the
demands. The most recent stride in this journey is the mechanical attributes of AM components. Research by
advent of hybrid manufacturing, which marries the Gupta et al. showcased the potential of this method,
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strengths of both subtractive and additive processes. This focusing on Ti-6Al-4V plates produced through SLM.
synergistic approach aims to produce bone plates that boast When juxtaposed with plates machined from wrought
the structural complexity enabled by AM, while retaining sheets, the value-add of AM in orthopedics becomes
the superior surface finish typical of subtractive methods. evident. Nonetheless, while the immediate benefits
However, the nascent state of hybrid manufacturing means are clear, queries regarding the long-term stability and
that its full potential is yet to be realized, necessitating dependability of such treatments persist. These concerns
further research and optimization, particularly given become especially pertinent when AM techniques are
the critical nature of bone plate applications where compared with traditional manufacturing methods.
structural integrity and biocompatibility are of paramount Furthermore, heat treatment can significantly enhance
importance.
material properties, making them more suitable for
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4.4. Perfecting additive manufactured bone plates biomedical applications. As elucidated by Hou et al. ,
with post-processing materials like the ZX11 magnesium alloy, although
promising, are subjected to rapid degradation. This raises
AM has substantially expanded the horizons of medical concerns about the longevity and stability of such implants.
device production. However, the creation of a bone plate Their study compared the degradation rates of the alloy in
does not end with the completion of the printing process. two states: as-rolled and annealed at 400°C. Their findings
Post-processing – the series of operations performed after revealed that while the annealed alloy exhibited relatively
the initial AM process – plays a pivotal role in ensuring lower strength, it benefited from a significantly reduced
that the bone plates are not only structurally sound but degradation rate and demonstrated stable elongation in the
also biocompatible. initial weeks of immersion, underscoring the importance
As the initial phase of AM often leaves parts with surface of heat treatment in optimizing material performance for
roughness or residual stresses, post-processing techniques biomedical implants.
such as heat treatment and surface modification become Another significant facet of post-processing is surface
indispensable. These treatments can profoundly impact modification, which has been thoroughly studied
the mechanical properties of the printed parts, enhancing concerning its impact on biocompatibility and cellular
their strength and fatigue resistance, which are paramount interactions. Surface characteristics, from roughness to
for bone plates subjected to significant mechanical loads chemical composition, can profoundly influence cell
during their life cycle . adhesion, proliferation, and differentiation, as highlighted
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Equally significant is the impact of these treatments by Gittens et al. and Stepanovska et al. . While
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on the biomedical properties of the bone plates. Surface these alterations can bolster implant performance, they
Volume 2 Issue 4 (2023) 9 https://doi.org/10.36922/msam.2113