Classifying Medical Devices - Medical Device Design: Innovation from Concept to Market - page 16

reusable so it falls into reusable surgical instruments ; it is Class I. We check with the agreed
definition of a reusable surgical instrument:
An instrument intended for surgical use by cutting, drilling, sawing, scratching,
scraping, retracting, clipping or similar procedures, without connection to any active
medical device and which can be reused after appropriate procedures have been carried out.
( EC, 1993 )
Clearly the drill bit fits this definition and it is a Class I device.
If the drill was intended to be single use only it falls into Class IIa, but you will need to justify
why it is single use as this incurs extra cost to the healthcare provider. Note how the phrase
intended use is very important.
Rule 7 takes into account longer durations of use. If the use of the drill was for longer than
60 min then its use would change from transient duration to short-term duration. Hence the
potential for risk to the patient increases and as such the class increases, but not enough to
change the standard classification. But note that the subrules have changed as their potential
risk increases with use.
Rule 8 takes this one stage further and puts implants and long-term surgically invasive
devices into Class IIb because their risk is greater. Note that this has been a matter of much
debate and has resulted in reclassification. The directive 2005/50/EC reclassified hips, knee,
and shoulder replacements as follows:
By way of derogation from the rules set out in Annex IX to Directive 93/42/EEC, hip, knee
and shoulder replacements shall be reclassified as medical devices falling within Class III.
( EC, 2005 )
This higher classification for these types of device is universally accepted. The term implant
has been universally adopted for a device that has been designed to remain within the body
with long-term duration.
There are a total of 18 rules (19 if you include the derogation above). I do not intend to go
any further as the point has been made. There is only one last technicality to include and that
is the use of animal by-products. Rule 17 states:
All devices manufactured utilizing animal tissues or derivatives rendered non-viable are
Class III except where such devices are intended to come into contact with intact skin only.
The rise of the prion and the fear of transmission of human variant CJD has made this
clause ever more powerful (we shall see this later when we look at application processes).
As designers we must be aware of our material and process choices. Do not forget that
animal tissue is used as the lubricant of injection molding machines and for thread cutting,