In 2012, 40 million Americans reported knee pain. With the U.S. population aging, participating in extreme sports more often, and becoming more overweight on average, that number is surely larger today. Anyone who experiences knee pain can attest to the range of negative impacts it has on daily life.


Chronic and acute knee pain does more than limit mobility. It can impede the ability to work, reduce social interaction and damage a person’s sense of well-being and enjoyment of life. There are many options for relieving knee pain. In this article, we explore therapies that use electrical machines. These therapies include:

  • Cold laser therapy
  • Infrared heat therapy
  • Ultrasound therapy
  • Electrical Muscle Stimulation
  • Interferential Current Therapy
  • TENS Transcutaneous electrical nerve stimulation

Cold Laser Therapy for Knees



Cold Laser Therapy (also known as low-level laser therapy or LLLT) is a popular option for treating knee pain without surgery or drugs. It is also safe to use in combination with other treatments, such as physical therapy. The concept behind LLLT: specific wavelengths of light can stop pain and swelling in connective tissue.


The FDA approves the use of LLLT, a biostimulation laser, for temporary pain relief, including knee pain.  For more information, go here:


What to Expect


A trained professional places a hand-held device over the injured area. The device emits specific wavelengths of light into the affected tissue. The clinician releases the low-level laser light for 30-120 seconds, depending on the dose prescribed. Determining LLLT doses depends on the extent of the injury and size of the injured area. Research into LLLT doses shows that there can be benefits to cold laser therapy but not in all cases. There is also no accepted standard for determining the dose and duration of treatment.


How Does Cold Laser Therapy Work?


Non-thermal photons of light pass through all layers of skin to reach the affected connective tissue. The light reaches the site of the knee pain and reacts with the light-sensitive components of tissue cells. Many people relate it to photosynthesis in plants.


In that process, plants absorb sunlight and convert it into energy for growth and repair. The theory is that the light activates cellular processes that reduce inflammation and edema. That kind of damage to connective tissue is one possible cause of knee pain. Research into the exact cellular processes at the root of LLLT continues. At the same time, no study has resulted in adverse effects to people receiving cold laser therapy.


Advantages of Cold Laser Treatments



The most obvious advantage of using cold laser therapy to treat knee pain is that it is non-invasive. This makes treatment more comfortable than surgery and significantly reduces recovery time. The fact that cold laser therapy has no side effects is also an advantage. The cost of LLLT is lower than surgery. The difference grows if you factor the cost of lost productivity and post-procedure care.


Disadvantages of Cold Laser Therapy


The disadvantage reported by most users is the length of treatment. Relief from knee pain can take 6-20 sessions. Variables include the extent and size of the affected area and the patient’s general health. The dose of LLLT and frequency of treatment sessions also play a role. Cold laser therapy is not covered in full or in part by all insurance plans.




It is best to avoid LLLT if there is the possibility of active cancer or lesions near the affected area. There is also no evidence to show it is safe for children under the age of 16 or pregnant women. While some cold laser therapy machines are not available to consumers, this one is available without needing a prescription, an obvious advantage for those wanting to avoid expensive treatments. 


Infrared Heat Therapy



A study on the effectiveness of infrared light therapy for low back pain relief, subjects who received treatment with infrared heat had an average reported pain level of 3 out of 10. That was down from 6.9 out of 10 at the start of the study.


The placebo group’s average reported pain level fell from 7.4 out of 10 to 6 out of 10. Infrared heat is a result of benign radiation. There are three kinds of infrared heat. The one used in infrared heat therapy because it can penetrate beyond the skin is IR-A. This Infrared Heat Lamp is reasonably priced and has excellent ratings.


How Do Infrared Heat Treatments Work?


Applied heat can promote the repair and rehabilitation of joints, muscles, and tendons. It improves the resilience of collagen. Collagen connects and supports muscles, tendons, ligaments, cartilage, skin, and bone. Heat therapy can also ease inflammation, reduce muscle spasms, and increase blood flow. Improved blood flow accelerates the delivery of nutrients and oxygen to the damaged area. 


There are many ways to deliver heat therapy. The most basic and accessible are a warm bath and hot compress. These remedies can be suitable for relief of minor and temporary pain. But for chronic or severe musculoskeletal pain such as knee pain, infrared heat is more effective.


Infrared heat increases the temperature of tissue, muscles, tendons, etc. below the skin. But the temperature of the skin itself doesn’t increase much at all. Because the skin doesn’t get hot, high levels of heat can be delivered to the damaged tissues. The duration of treatment can also be longer. 


Infrared Heating Pads



Those designed for knee pain mold to the curvature of the knee joint when straight and bent.  For more information, click here: 


Advantages of Infrared Heat Therapy


The most obvious advantage is the comfort to effectiveness ratio compared to hot compresses. In other words, you get the benefit of heat therapy without burning your skin. Most heat therapy provides some immediate relief. Heat therapy delivered by an infrared heating pad is no exception.


These devices are common in clinical environments and can also be purchased for home use. Infrared heating pads are convenient. Most are compact with Velcro straps to keep the pad in place. Portability makes them popular among travelers, especially adventure travelers. Higher-end models have a USB connector. This allows you to power the heating pad with a phone, tablet, or laptop. This is a definite advantage when hiking or traveling to remote areas.



Disadvantages of Infrared Heat Therapy


It can take 5-20 sessions to achieve long-term relief, depending on the extent of the damage. Often, the best results come from a combination of heat therapy and physical or massage therapy. With at-home infrared heat therapy, trial and error is to be expected. Finding the optimal treatment duration and frequency can take time. For best results, consult with a trained professional before starting at-home treatments.



If you are thinking of using an infrared heating pad at home, look for a product with FDA approval. Models with auto-shut off timers help prevent excessive heat, which can stress or damage soft tissue. Read product reviews and watch for comments about heat level and fit. Also, investigate portability if you intend to travel.


Ultrasound Therapy


Ultrasound therapy for pain relief can be thermal or mechanical. Many types are FDA approved when delivered by a qualified technician. However this one is certified for home use, saving trips to a physical therapy office.



How Do Ultrasound Treatments Help Knee Pain?


Thermal ultrasound uses the continuous transmission of sound waves to create vibration deep below the skin. Vibration causes cells to warm up. The additional heat increases the cells’ metabolism and improves the healing of soft tissue. Mechanical ultrasound therapy sends pulses of sound waves through the skin. Along with a mild warming effect, the pulses contract and expand gases found in soft tissue. Changes to the gas help reduce inflammation and pain.


What To Expect


A transducer, which looks like a small hand-held shower head, delivers sound waves. A qualified therapist applies gel to the transducer or the affected area. Gel facilitates movement across the skin and improves the sound waves’ ability to penetrate the skin. The therapist moves the transducer over the affected area for 5-10 minutes.


Some people report feeling warmth at the affected area or a mild pulsing beneath the skin during the treatment. Ultrasound therapy should never be painful. Weekly treatment is common until the pain is significantly reduced. Time between sessions is then extended until healing is evident by the absence of pain. People with pacemakers shouldn’t receive ultrasound therapy for pain. The model featured here is suitable for home use.  


TENS — Transcutaneous Electrical Nerve Stimulation



Transcutaneous electrical nerve stimulation (TENS) is an electroanalgesia. That means it uses low-voltage electrical pulses designed to relieve pain. Most often, it’s used to treat muscle and joint pain, including knee pain. It can also offer relief from pain caused by osteoarthritis and fibromyalgia. Research into the effectiveness of TENS is ongoing. There is no conclusive proof yet of its reliability as a method of lasting pain relief.


How Does a TENS Machine Work?


Two electrodes connect the TENS machine to the skin. Both can be placed at the pain site. Or, one can be at the pain site and the other placed on a related pressure point. With the electrodes in place, a circuit along nerve pathways is created. A battery in the machine delivers a low-voltage current to the body.


Settings for amplitude (intensity), current duration, and current rate (frequency) can be modified. Most machines are able to deliver a near continuous current but this generally inadvisable. Continuous current can create a kind of nerve fatigue. Many people report decreased pain levels in response to the current.


There are two prevailing theories to explain why. The first theory is that the electricity stimulates the nerves in an affected area. Signals sent to the brain block or override the pain signals. The second theory: electric stimulation of nerves promotes the production of endorphins. Endorphins are the body’s natural painkiller.



Common TENS Therapies


Conventional TENS therapy uses high frequency and low-intensity current in short pulses. Pain relief comes quickly and lasts while the current is on. In the absence of the current, pain slowly returns. Using the conventional method, patients can use TENS for 20-30 minutes many times throughout the day.


Another TENS therapy is related to acupuncture in that the electrodes are placed on acupuncture points. The frequency of electrical pulses is moderate but the intensity is high. Not as many people can tolerate this method, compared to the conventional therapy.


Acupuncture TENS is most often used for people seeking the benefits of acupuncture but have a fear or intolerance of needles. The pulsed TENS therapy is similar to the conventional method in that it uses short pulses of electricity. The difference is that the intensity of the burst is greater.


Electrode positioning is important and can require trial and error. Putting an electrode on the skin at the pain site is straightforward. But if the other electrode is not on top of trigger points, acupuncture sites, or cutaneous nerves, there may be minimal pain relief. (The cutaneous nerves related to knee pain are usually the anterior cutaneous branches of the femoral nerve and the posterior cutaneous nerve of thigh.)


Advantages of TENS


You can perform at-home therapy once a qualified professional has shown you how to use a TENS machine. They should also provide you with the appropriate settings. Before buying a TENS machine, it’s advisable to share the model and features with your healthcare provider. He/she can ensure the equipment is appropriate for your needs.


Disadvantages of TENS


TENS shouldn’t be used by anyone who is pregnant or has a pacemaker. Learning the proper placement of the electrodes to address your unique circumstances is critical. Electrodes shouldn’t be placed on any part of the body where the person has nerve damage or sensory impairment. Some reports state that about one-quarter of users report skin irritation at electrode sites. TENS machines for at-home use are generally not covered by insurance. Treatments in-clinic might be.  


Other Treatment Machines for Knee Pain


Cold laser, infrared heat, ultrasound, and TENS therapies comprise the majority of therapies offered. But others are available and in some cases becoming more prevalent.


Electrical Muscle Stimulation



The primary purpose of Electrical Muscle Stimulation (EMS) therapy is strengthening and rehabilitating muscle. Some users report a secondary benefit of pain reduction. EMS uses electric impulses to cause small and frequent muscle contractions.


The placement of multiple electrodes isolates which muscles are exercised. In many cases, one machine can deliver both EMS and TENS therapy.  


Interferential Current Therapy



Interferential current therapy (ICT) is like TENS except it uses low-intensity current at ultra-high delivery rates. The electricity is less intense but goes deeper below the skin. Many report pain relief from ICT lasts longer than that from TENS. ICT machines can have 2, 4, or 6 electrodes. There are reports that more electrodes further improve the duration of pain relief. Like with TENS, people who are pregnant or have a pacemaker shouldn’t undergo ICT. 


Get the Right Treatment for Your Knee Pain


Of course, whenever possible, prevention of knee pain is best. But if you are experiencing chronic or intense pain, it’s only natural to seek relief. If common approaches such as supplements, massage or physical therapy don’t bring the results you want, treatment machines might be the answer. Often, they are a reasonable next step before considering the more complex, invasive, and expensive route of surgery. The journey to discovering the right treatment for your knee pain is personal. We invite you to explore all the information on this site to help you find the treatment that’s right for you.

Last update on 2019-05-24 / Affiliate links / Images from Amazon Product Advertising API