Medical Design Briefs - October 2022 - 17

presents a much greater risk to the patient
than the original surgery. A study of
hip replacements shows only just over 80
percent of implants will last longer than
25 years, a number that could potentially
increase with AM produced implants.2
Unique Benefits of Additive
Manufacturing
One of the primary concerns for any
implant is whether it will be accepted by
the body. AM techniques allow for the
inclusion of porous structures within the
implant, a crucial feature that allows for
the biomedical fusion of the implant.
Manipulation of implant porosity also
allows for weight reduction of the part,
helping it to better match actual bone
density. Research has shown that porosity
can be manipulated to alter the
mechanical properties of the implant.
1For example, a spinal implant should
flex and compress a similar amount to
the adjacent spinal discs to avoid introducing
excessive pressure and subsequent
pain for the patient. Adjusting
the porosity allows the implant to match
the mechanical stiffness of the natural
surrounding bone. These design improvements
all translate to improved
outcomes for the patient, minimally invasive
surgeries, and reduced possibility
of implant failure down the road.
Outside of the realm of patient care,
another unexpected benefit of additive
manufacturing is its ability to completely
upend the existing supply chain and distribution
of biomedical implants. Especially
today, as supply chains are increasingly
susceptible to material shortages and
the costs of transportation are skyrocketing,
the opportunity to mitigate these risks
is highly desirable within the industry. AM
manufacturing requires less material input
than traditional manufacturing and
produces much less material waste, reducing
the supply chain burden. The overall
process for AM also requires less space
and fewer steps to produce a finished
product, meaning a more localized distribution
network can be utilized. This is
particularly advantageous for fully customized
implants, which could potentially be
prototyped and/or produce at the point
of care, eliminating non-value-added steps
of the supply chain. The proximity of the
production to the point of care also enables
greater physician feedback into the
production process, making them a key
stakeholder in the supply chain.
Medical Design Briefs, October 2022
Process Validation Challenges
Within the biomedical industry, novel
innovations always experience significant
regulatory hurdles before being
commercialized and widely adopted.
Implants are considered class 3 products
by the FDA, the most scrutinized
class of product due to the impact of
potential failure to the patient. Guaranteeing
implant safety is further complicated
by the long-term usage of the
product, requiring premarket approval
(PMA) to prove efficacy and safety. AM
processes introduce numerous variables
to manufacturing (see Table 1).
Process validation requires a complete
understanding of how each of these AM
process parameters will affect the device
quality and performance. Studies are
required to ascertain the process repeatability
within a given build cycle, across
multiple build cycles, and on different
printing systems within a facility. Additionally,
all the system software will need
to undergo proper validation per 21
CFR 820. Despite the effort required to
fully validate an AM process, the benefits
to both the manufacturer and patient
are clear, providing efficiency cost savings
and improved efficacy, respectively.
These hurdles are actively being tackled
by some of the largest implant manufacturers
in the industry, as the FDA has
only released guidance documents to
A 3D printed dog bone shaped test specimen, also known as a coupon. (Credit: Instron)
A universal testing machine can be used to perform a wide range of mechanical tests, including tensile, compression,
flexure, torsion, and more. (Credit: Instron)
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Medical Design Briefs - October 2022

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