Biomedical Engineering Reference
In-Depth Information
17.11 The Use of Standards in FDA
Regulation
Table 17.3
Examples of Information Commonly
Found in a Material's Master File
We close this chapter with a discussion of stan-
dards documents as they are used in the regulation of
medical devices. We describe the three major types
of standards, the development process, their benefits
and limitations, and the current American Society for
Testing of Materials International (ASTM) standard
for PEEK polymer.
Basic chemical and structural information
Mechanical properties of the bulk material
Thermal properties of the bulk material
Biocompatibility information (e.g.,
testing per ISO 10993)
Animal testing results
Clinical data from devices utilizing material
17.11.1 Types of Standards
There are three main types of standards that are
relevant to orthopedic or spinal implants and other
medical devices: material specifications, standard
test methods, and standard test guides. These types
of standard serve very different purposes.
Material
specifications
list chemical and physical properties
that a material must possess in order for a material
supplier to claim that their material meets the
standard. ASTM International (formerly the
American Society for Testing and Materials), for
example, publishes many standard specifications for
most of the major surgical alloys (e.g., titanium
alloy, stainless steel, cobalt chrome) and metals as
well as for medical polymers such as ultrahigh-
molecular-weight polyethylene (UHMWPE), acrylic
bone cement, and PEEK.
Standard test methods
describe how to set up and conduct a test of
a specific physical or mechanical property. Specific
test parameters such as the number of samples to be
tested or the amount of load are specified, as well as
a description of the measurements or properties that
should be reported as results. Note that most stan-
dard test methods do not define acceptance criteria,
but rather leave this responsibility to the user based
on the intended application of the device. Standard
test methods are beneficial because they defines
a protocol for producing repeatable, reliable results
and avoid the need for every manufacturer to invent
a new test method each time a new design is being
developed. Finally, a
standard test guide
usually
precedes the development of a test method. Typi-
cally, when the process of developing a new standard
is beginning, the devices that are intended to be
tested are still undergoing early clinical evaluation,
and their in vivo performance and potential failure
modes are unknown. In cases such as these, the
standard will be written in a more general fashion,
specifying tests
Effects of common sterilization techniques on
material properties
device in a particular anatomic region does not ne-
cessarily justify the use of that material in a different
device type or anatomic region. Additionally, a device
and material should be justified in its final sterilized
form. For this reason, Master File type information
may be insufficient to justify a particular material for
a particular use. Most devices are required to undergo
specific preclinical tests prior to reaching market,
particularly if manufacturing or other processing
steps would affect the biocompatibility or other
properties of the material. The Master File will likely
not replace the need for such testing. However, Master
Files do allow a company to reference important
information, particularly biocompatibility informa-
tion for the bulk material, without the company or
FDA reviewer having to start from ground zero each
time a particular material is reviewed.
An authorization letter is required from the Master
File holder (in this example, the material supplier
would be the Master File holder) each time the file is
referenced in a submission. Once the basic infor-
mation in the file has been reviewed by the FDA for
one device, the hope is that it may not need to
be reread in such detail for each subsequent
submission, which is intended to make the Master
File process efficient for all parties involved. Note
that in reality, because the FDA must sometimes
correspond separately with the device and material
manufacturers to gather required information, at
times this process can be slightly less efficient than if
the manufacturer has access to all the information
themselves.
For more information on Master Files, we would
recommend consulting the FDAwebsite's section on
Master Files
[8]
.
and methods
that
should be
