Can TENS and Muscle Stims (EMS machines) be safely used by people with metal implants?
This is a question Natures Gate often get asked and the answer is yes. Many people who have had pins, plates, wires, nails or screws to reconstruct or replace their malformed or degenerated joints find that TENS machines are useful for their pain relief and muscle stimulators are useful with their rehab. They are however concerned if these are safe to use.
Metal implants (most commonly) hip and knee replacements are widely considered to constitute a contraindication to most, if not all electrotherapy modalities - though in fact studies have shown that this is not actually the case for many.
When considering electrotherapy to treat conditions it is important to determine if the device is PASSIVE or ACTIVE.
TENS and muscle stimulators (also known as EMS, NMES or NMS machines) are battery powered and are categorised as PASSIVE devices.
The major concern is that the applied energy will result in ‘significant’ heating of the metallic implant, which would have a detrimental effect in the local tissues surrounding that implant, raising the tissue temperature to damaging levels. Whist that would almost certainly be true for some electrotherapy modalities (most especially the high frequency heating modalities - shortwave and microwave in particular), it is not true for many others.
Electrical stimulation modalities (TENS, Interferential, NMES etc) are not contraindicated as the amount of energy applied is not sufficient to cause a detrimental heating effect in the tissues surrounding the implant, though the presence of metal in the tissues will almost certainly distort the pathway taken by the applied current and may therefore generate some unexpected effects in terms of sensation experienced by the patient. Passive metal implants are NOT therefore a contraindication to the electrical stimulation modalities (ACTIVE implants are though)
We always recommend that you also consult with your doctor and always fully read the User Guide for all Natures Gate units and pay particular attentions to our Contraindications, Precautions and Warnings.