1. We don't use contacts when we have metal parts within because the metal will conduct more easily than the flesh, so the current will tend to flow through the metal, which could cause sensations (or in extreme cases, burns) where it enters and leaves the metal. This may also alert the body to the "foreign matter" and be cause for rejection. Plasma and Remote are the modes that should be used in these cases.
2. My right tibia and fibula are held together by titanium plates, rods, pins, and screws. I found that Contact Mode made the implants "buzz" uncomfortably. Reducing the amplitude to 80% fixed it.
3. We have the amplitude reduced as well. I have used it like this for several sessions and haven't felt anything, except an occasional tingle where the pads are located.
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