This is substantial equivalence?
The type of device which the FDA has called "Diathermy, shortwave, for use other than applying therapeutic deep heat" (Product Code ILX) has been of particular interest to me since 1976, during my employment in the Bureau of Medical Devices, FDA.
The archetype of this type of device was first introduced into the market around 1959, and was promoted as a therapeutic device for wound healing. The FDA found fault with the labeling, culminating in an injunction in 1972 prohibiting the company from selling its product in interstate commerce.
More years of litigation ensued. Meanwhile, the FDA caused hundreds of the devices to be seized from doctors' offices and clinics around the country. Most devices were destroyed or buried in landfills.
Finally, the company prevailed - sort of - and was permitted to resume sales in the U.S. with a very limited label: The device could be promoted as an adjunctive therapy for the mitigation of pain and edema in superficial soft tissue. The company resumed marketing in the U.S. in 1987.
Because the product had been in distribution before 1976, it is considered to be a pre-enactment device. This is important because at least one other company used this product as a predicate in a 510(k).
The company has always maintained that their product is not shortwave diathermy despite its similarity to diathermy. What distinguishes this machine from conventional diathermy is that the output is pulsed. The output pulses are 65 microseconds long. Although the peak power is 975 watts, the maximum average power is only 38 watts.
The FDA has always maintained that the product is shortwave diathermy.
The device, in case you haven't guessed yet, is Diapulse.
FDA's argument concerning Diapulse is rather simple. They consider it to be a diathermy device. But diathermy devices are required to be capable of elevating the temperature in the treated body part to 104 deg F within 20 minutes. FDA "experts" did not know of any therapeutic effect of radio-frequency energy aside from the heating effect. Diapulse does not deliver enough power to the patient to meet the criterion for diathermy. Therefore, Diapulse was thought to be ineffective and was declared a quack device.
Research using Diapulse has amply demonstrated not only its effectiveness, but its superiority to conventional diathermy. See the annotated bibliography for details.
A number of manufacturers have submitted 510(k) notices for ILX devices, with Diapulse as the original predicate device.
The table below shows the companies and products cleared under 510(k) notifications in device category ILX between 1991 and 2009.
MFR 510(k) PREDICATE CLEARED
MRT K903675 Diapulse® 01/17/1991
Regenesis K972093 MRT SofPulse 10/21/1997
PAW K022404 MRT SofPulse 08/08/2002
ProMedTek K070931 MRT SofPulse 05/24/2007
Ivivi Tech. K070541 MRT SofPulse 12/11/2008
OrthoCor K091996 Ivivi Tech. Torino II 12/15/2009
The next table lists the maximum peak powers for some of the devices in the prior table.
Ivivi Technologies' 510(k) actually covered three devices listed below.
(Regenesis and PAW devices are excluded from the table.)
Manufacturer Device Peak Power, Watts
Diapulse Corp. Diapulse® 975
MRT SofPulse 400
Ivivi Technologies9 912-M10 10
Torino II 1.8
ProMedTek PMT850 0.043
OrthoCor Knee System 6.5 p.Ws/cm3
CDRH determined all of these devices to be substantially equivalent to their respective predicates.
Clearly, CDRH reviewers were convinced by the evidence presented in these 510(k)s that the devices were substantially equivalent despite the huge decrease in peak power. Because the 510(k) notices obtained under FOI were so heavily redacted, I could not tell what experimental evidence or theoretical argument convinced CDRH reviewers that these were substantially equivalent.
Somehow, it seems to defy common sense that devices are "substantially equivalent" when a key parameter has decreased by orders of magnitude!
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