Biomedical Engineering Reference
In-Depth Information
17.5 Medical Device Definition and
Classification
By 1930, the Bureau of Chemistry had slowly
transformed into the FDA, and there was new public
outcry against some of the harmful products that were
still technically legal under the 1906 law, most notably
a product called “elixir sulfanilamide” that contained
the chemical equivalent of antifreeze and was associ-
ated with the death of more than 100 children in 1937.
This reaction helped propel a new bill in Congress and
in 1938, the Federal Food, Drug and Cosmetic Act
replaced the 1906 law and required that all drugs be
preapproved by the FDA and that they be labeled with
directions for safe use. It also brought medical devices
and cosmetics under FDA control for the first time,
although PMAwas not yet required for devices.
Finally, in 1976, the Medical Device Amendments
were signed into law by President Gerald Ford. They
required the manufacturers to follow strict quality
control protocols, and it stipulated that new medical
devices were now subject to PMA. As with most of the
previous FDA-related laws, these amendments were
motivated largely as a reaction to a disaster or crisis.
The Dalkon Shield, an intrauterine device introduced
onto the market in 1971, had been designed to prevent
pregnancy but inadvertently introduced bacteria into
the uterus. Based on results of short-term preliminary
studies that were later criticized for their study design,
the marketing for this device included claims that
were false regarding its use, effectiveness, and safety.
Use of the device led to infections, pregnancies,
infertility, and deaths
[4]
, all of which convinced
many people that PMA of devices based on well-
designed, scientifically valid studies was needed.
A number of additional, more recent laws have
expanded upon or attempted to improve the 1976
Medical Device Amendments: these include the 1990
Safe Medical Devices Act, the 1997 Food and Drug
Administration Modernization Act, the 2002 Medical
Device User Fee and Modernization Act, and the
2007 Food and Drug Administration Amendments
Act. Among other things, these laws established
a system for reporting adverse events to the FDA,
standardized the time lines of the device review
process, began regulating advertising of medical
devices, established a system whereby manufacturers
now pay fees to the FDA for review of device
applications, and encouraged research and develop-
ment of pediatric treatments
[5]
. As new technologies
are developed, and as new threats to device safety are
identified or crises inevitably emerge, new laws will
undoubtedly be devised to address them.
A medical device is defined in Section 201(h) of
the Food Drug and Cosmetic Act as anything that is
used to diagnose, treat, mitigate, cure, or prevent
a disease, but which does not achieve its primary
purpose through chemical action and is not metabo-
lized. This definition effectively encompasses any
object that is used for medical care but is not a drug
or a purely biologic product. In a doctor's office,
objects as seemingly simple as the examination table,
packages of gauze, or a stethoscope are considered
medical devices. Traditionally, however, the term
“medical device” is more often used for more
complex technologies like MRI machines, hip
replacements, spinal fusion cages, pacemakers, and
artificial heart valves. Because of this diversity, and
because greater scientific review is needed for some
devices than for others, all medical devices are
grouped into three classes. Devices are grouped into
these classes according to their intended use and risk
profile, so that the FDA can apply an appropriate
level of scrutiny to each one.
Device classifications are defined in the Medical
Device Amendments of 1976 and are based on inten-
ded use, indications for use, and risk. Soon after those
amendments were passed, an advisory panel to the
FDA attempted to catalog and assign classifications to
all existing device types. The results of this effort can
be found in the Code of Federal Regulations, Title 21
(Food and Drugs), Chapter I (FDA, Department of
Health and Human Services), Subchapter H (Medical
Devices), which is continually updated as new devices
are introduced and regulations are modified. This
section of the federal regulations has individual list-
ings that describe different types of device, including
how they are identified, their classification, and
whether any specific special controls or guidance
documents apply to that type of device. For example,
intervertebral body fusion devices (IBFD or cages) are
addressed in Section 888.3080 of the regulations,
which describe a cage as “an implanted single or
multiple component spinal device made from a variety
of materials
.
The device is inserted into the inter-
vertebral body space of the cervical or lumbosacral
spine, and is intended for intervertebral body fusion”
[21 CFR 888.3080]. The regulation also specifies that
these devices are Class II (unless they include thera-
peutic biologics such as bone morphogenic protein, in
