Is TENS safe to use for knee pain?
TENS, transcutaneous electrical nerve stimulation, is a drug free way to reduce pain in the knee caused by arthritis, inflammation, and most other degenerative changes.
TENS stimulation for knee pain after knee replacement
How does TENS reduce knee pain?
The formal explanation is it will “reduce pain by activating descending inhibitory systems in the central nervous system to reduce hyperalgesia.”[1]
The real world explanation is the device provides a different feeling which confuses the nerve endings at the site of pain.
Is TENS Safe?
The original TENS unit was patented in 1974 and has been used since then with minimal complications. The most common complication associated with TENS is skin irritation which may account for up to 33% of users and is often attributed to a drying out of the electrodes. [2]
The main contraindication for using a TENS unit is having a pacemaker. DO NOT Use a TENS unit if you have a pacemaker.[3] If you are unsure always consult your physician before using any medical device.
Where do I place the TENS pads around my knee?
The most common pad placement for knee pain is a criss cross pattern around the knee.
In this video I explain how the TENS unit works and where to place the pads based on the location of your pain.
Also, in the following photos you can see several pad placements for different pain locations.
What settings should I use on the TENS unit?
In this video I recommend pulse rate at 120 and pulse width at 70.
I also recommend experimenting with different settings to see what feels best to you.
How long do I keep the unit on?
Duration of use depends on several factors. In my clinic I usually recommend a maximum of 15-minutes of use per episode.
Some patients may find longer than 15-minutes produces skin irritation.
If my client is experiencing a persistent episode of pain and wants more use time I recommend cycling the use of the device by turning it on for 15-minutes, then off for 15-minutes and repeating this cycle for up to 4 cycles.
The pads may be left on the skin during the 15-minute episodes in which the TENS unit is not turned on.
How often should I use the unit?
The TENS unit may be used as frequently as several times a day or as infrequently as once a month.
Since the device is primarily a way to empower you the patient with a pain management strategy that is not dependent on medication, the frequency of use is dependent on your needs at the time.
How should I position my leg when the TENS unit is on?
Leg positioning may be most comfortable when you place a small pillow under the bend of your knee and the leg is propped up on a bed, ottoman, or recliner.
If swelling is a concern you want to position your body in a reclined position and elevate the leg to a level higher than the level of your heart.
One study suggests 45-degrees or higher elevation of the leg is ideal to reduce swelling. [4]
Can I use a TENS unit while on a CPM Continuous Passive Range of Motion Device?
TENS while using Knee CPM
Yes, TENS is a great way to make time on a CPM more enjoyable.
Continuous Passive Range of Motion is a device used to move your knee during recovery.
Some surgeons recommend it for the first 30-days after total knee replacement surgery.
Should I use ice or moist heat while using the TENS unit?
The most common recommendation when combining pain modulating (reducing) modalities is to use ice with TENS.
The typical parameters is to add a cold pack over the TENS electrodes for up to 15-minutes to reduce pain in a knee joint.
If you are sensitive to cold therapy and prefer heat, a warm compress or dry heat may be appropriate.
In this article researchers reviewed the difference between moist heat vs dry heat and found that:
“It should be noted that moist heat had not only similar benefits of dry heat but in some cases enhanced benefits, and with only 25% of the time of application of the dry heat.”
Can I use the TENS unit on my knee while walking?
Yes, the greatest benefit of a TENS unit is the fact that it is lightweight, inexpensive, and easy to use while being active. A TENS unit may be used on the knee while walking to reduce knee pain.
You may clip the TENS unit on your waist band and run the electrode wires under your clothing.
Can I use the TENS unit while driving?
It is not recommended to use a TENS unit while driving.
For a comprehensive list of when to avoid using a TENS unit click here to view this University of Iowa Hospitals & Clinics Website
Can I use the TENS unit while working?
Depending on your occupation, TENS may be an appropriate way to reduce pain while working. For most clerical and administrative duties, TENS may be worn under the clothing. For other more physically demanding occupations consult your physician or physical therapy to find out if TENS would be appropriate for you.
Other Resource:
ELECTROPHYSICAL AGENTS – Contraindications And Precautions: An Evidence-Based Approach To Clinical Decision Making In Physical Therapy [6]
Downloadable PDF University of Iowa Pamphlet for Safe Use of A TENS Unit
Citations:
Anthony Maritato, PT
Physical Therapist
Anthony Maritato, PT has been a licensed physical therapist and private practice owner since 2006. Ohio license #PT011602.
Anthony has been passionate about helping patients recover from total knee replacement surgery as well as rotator cuff repair surgery.