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Class IV Laser Therapy For Knee Pain

Overall Benefits of a Class IV Laser for Chronic Pain

Light has for thousands of years been recognized as an energy with therapeutic effects. Today, this information has evolved into the use of laser devices and machines that can send controlled amounts of lights into your cells as a form of treatment. The light treatment process does not address only disease symptoms but also treats the root causes of those diseases. In general, light therapy has been found to provide long-term therapeutic benefits to patients.

Laser therapy can be described as a medical treatment that light to bring about health effects in a tissue. It employs a specific wavelength of focused light in medical science to interact with tissues and stimulate the process of photobiomodulation (PBM) or photobiostimulation. Photobiomodulation is the process by which electromagnetic energy in form of protons, is introduced into a cell or tissue. Within the cell or tissue, these protons interact chemically and biologically with the cytochrome c complex in the cells’ mitochondria. This interaction proceeds to yield therapeutic effects.

This use of electromagnetic energy is not new to our bodies. The cells and tissues in our bodies naturally use this energy to fuel their actions and carry out physiological functions. These include the production of beats by the heart, sending of signals by the brain, nerve stimulation, and cellular metabolism.

Compared to other lines of treatment such as drugs and surgery, light or laser therapy has been proven to aid natural body healing through photochemical processes. Other benefits of laser therapy include reduction and relief of pain, reduction in inflammation, decrease in muscle spasm, promotion of wound healing, tissue regeneration, immunomodulation, increase in cellular metabolism, increased range of motion, and improvement in body blood microcirculation, amongst others.

The use of laser devices has been proven to be safe, has little to no side effects, is specific, convenient, and quick in providing treatment without drugs or surgery. It has also been cleared by the FDA as a non-invasive, non-pharmacological treatment for pain relief. Research shows that it is equally effective as other forms of rehabilitation and in some cases, more.

What is Class IV Laser?

Lasers are classified into eight classes according to how much harm the laser beam can cause. These are classes I, I Product. IM, II, IIM, IIIR, IIIB, and IV. Class IV laser ranks the highest in classes of lasers and is the most hazardous class of laser radiation. It is high-powered in terms of wavelength, power, energy, and pulse duration. It is mostly used in medical practice for surgical and cosmetic purposes.

However, it is hazardous to the eye. In order words, prolonged exposure can cause harm to your eye and result in eye damage. Class IV lasers are powerful enough to burn and cause significant harm to your skin. Hence, your eyes and skin must be protected from direct or reflected light from direct laser beams or scattered beams. Class IV lasers can potentially burn materials within close range, particularly lightweight and/or dark materials. If not appropriately handled, class IV lasers can result in a fire incident and produce poisonous fumes.

Class IV lasers could be visible or non-visible. There are only four classes of visible-beam lasers- class II, class IIIR, class IIIB, and class IV. The power output or continuous wave (CW) of visible-light class IV lasers is 0.5 watts or 500mW and above. In pulse systems, these lasers can produce more than 125mJ below 0.25 seconds.

Hence, class IV laser therapy is the use of high-powered laser light focused and sent into tissues to reduce pain, swelling, and inflammation, and boost healing.

Differences between Class IV Laser Therapy and Cold Laser Therapy

Cold laser therapy is a light therapy that uses Class IIIB lasers. In medical practice, they are limited in use as opposed to class IV lasers. The following are differences between class IV lasers and cold (class IIIB) lasers and/or laser therapy.

Class IV therapy

Cold laser therapy


Use of high-powered, intense devices.

Use of “low-powered, LLLT (low-level laser therapy), cold laser’ devices.

Power output

The minimum power output of laser used is 500mW or 0.5W

The minimum power output is 5mW and the maximum power output of the laser used is 500mW or 0.5W


The most recommended primary wavelength for treatment is either 810nm or 980nm.

The wavelength used for the treatment ranges from 600nm to 980m.

Range in medical practice

Wide range, used in medical, surgical, cosmetic, and military purposes.

Limited range, used for wounds, superficial lesions, to relieve pain and swelling, reduce fat, improve circulation, etc. If used for other deep tissue and musculoskeletal problems, a long period of treatment is required which is not recommended in medical practice.

Time to yield therapeutic effects

Yields therapeutic effects within the shortest time possible.

Takes more time to yield therapeutic effects compared to class IV therapy.

Treatment surface area

Covers up to 77cm2 treatment surface area

Covers treatment surface area of 0.3cm2 to 5.0cm2

Hazard potential

Class IV laser poses a severe hazard risk to the eye, skin, and materials. Also, poses a fire risk.

Cold laser poses hazard risk (lower than Class IV laser) to the eye and skin.

Effect of laser used on the eye

Can damage your eye instantly if you stare at the laser dot.

Can damage the eye if you stare at the laser dot for many seconds within close range.

Production of diffuse reflections

Class IV lasers can produce diffuse reflections that are as hazardous as the light beams themselves

Cold lasers do not produce diffuse reflections, except for high-power class IIIB lasers.

Nominal ocular hazard distance (the distance between the unobstructed laser beam and the eye. Do not stay within this distance)

733ft (224m) for light beams that have a power output of 1000mW or 1W.

2320ft (710m) for light beams that have a power output of 10000mW or 10W

520ft (160m) for light beams that have a power output of 499.9mW

Effect of laser used on the skin

Class IV laser can burn the skin instantly.

Cold laser can heat the skin if the light beam is held at close range to the skin and long enough.

Effect of laser used on materials

Class IV laser can burn materials instantly.

Cold laser can burn materials if light beams are held long and close enough to them.

Control required

Requires significant control

Require specific control

Advantages of Class IV Therapy over Cold Laser Therapy

The use of cold laser therapy in medical practice is limited because of low energy, low dosage, and poor penetration. This is in comparison with the class IV therapy. Hence, advantages of class IV therapy over cold laser therapy include the following:

Higher amounts of therapeutic energy and faster treatment time

Class IV laser therapy provides higher wattage of therapeutic energy to cells and tissues, thus ensuring better positive outcomes. The higher the amount of energy delivered, the shorter and faster the treatment time. Compared to cold laser therapy, class IV laser therapy delivers up to 1,500 more energy to treat pain and other medical conditions.

Greater power density

Class IV laser therapy does not only produce more power output but more concentration of the power output. With more power density, more therapeutic outcomes are achieved.

Continuous power supply

With class IV lasers, you enjoy a continuous power supply and light can pass through the probe throughout the total operating time. This is unlike cold lasers where the power is pulsed half of the time, hence light can only be passed for half of the operating time.

Consistent dose of energy

Usually, class IV lasers deliver a steady and constant amount of energy over a given treatment period.

Deeper penetration into tissues

Class IV laser therapy provides a deeper depth of penetration into body cells, tissues, and organs within the shortest time possible. While class III lasers can penetrate depths of 0.5cm2 to 2.0cm2, class IV laser therapy provides deep tissue penetration up to 10cm2. This penetration provides effective tissue healing.

Wider treatment surface area

Class IV laser therapy covers more treatment surface area than cold laser therapy. This makes it the best option for areas like hips, lumbar spine, and quadriceps. Cold lasers cover treatment areas from 0.3cm2 to 5.0cm2 while class IV laser therapy covers up to 77cm2 of treatment surface area.

Superior fiber optic cables

Fiber optic cables transmit light energy from the laser to the probe. Class IV lasers have fiber optic cables of better quality and function than cold lasers where up to 50 percent of the energy produced could get lost before it gets to the end of the probe.

The Science behind Class IV Laser Therapy

Class IV laser therapy works via the process called photobiomodulation (PBM). During PBM, electromagnetic energy, that is protons are introduced into the cell or tissue in the body and interact with the cells’ mitochondria. This interaction generates biological and chemical reactions that bring about therapeutic effects such as pain relief, inflammation reduction, muscle relaxation, and tissue repair, amongst others. Factors that determine photobiomodulation include:

● Type of light

● Light wavelength

● Operating modes

● Power

In class IV laser therapy, the wavelength length of the laser provides deeper penetration depth than other classes of laser radiation. Hence, energy enters into deep tissues, nerves, ligaments, tendons, and muscle tissue in lesser time. Therapy sessions last between 2-6 minutes and provide for more and larger treatment surface areas to be treated.

Class IV laser therapy stimulates several photochemical processes including:

● Stimulation of cytochrome c

● Generation of ATP

● Accelerated DNA and RNA synthesis

● Increased collagen synthesis

● Enhanced levels of beta-endorphins and serotonin

ATP (adenosine triphosphate) production also facilitates several cellular processes including healing and regeneration processes within cells. Studies show that after class IV therapy, patients reported reduced pain, swelling, and inflammation, increased range of motion, and wound healing.

Application of Class IV Laser Therapy

Class IV laser therapy is used for the following reasons:

To reduce pain, aches, and inflammation

Class IV devices are used for patients who suffer from acute and chronic pain, and inflammation. The mode of action of these devices is photochemical, that is using light energy to stimulate chemical reactions that relieve pain, aid wound healing, and boost blood circulation. These include:

● Promoting muscle relaxation, hence, reducing pain from muscle cramps and spasms

● Reducing joint pain and stiffness

● Reducing arthritic pain symptoms

● Improving blood circulation

● Treating post-surgical wounds and pain

To recover from injuries (acute and chronic)

Class IV laser therapy is used to treat acute and chronic injuries. Examples include tendonitis, strains, and sprains. These injuries also result in pain and inflammation and hence, laser therapy comes in handy in treating both pain, swelling, and other signs of inflammation, as well as aid treating.

Recovery can also be boosted by stimulating immune system response, nerve regeneration, and muscle relaxation.

To treat skin disorders including scars, burns, wounds, etc.

Class IV laser therapy can promote the healing of several skin conditions such as wounds, lesions, burns, and scars. Surgical incisions can also benefit from laser therapy, as it also reduces the risk for infections.

To treat neuropathy

Neuropathy is a term used to describe nerve damage. Nerve damage can bring about symptoms such as pain, muscle cramps and spasm, tingling sensation, numbness, loss of function, and bone degeneration. These symptoms can be relieved by administering class IV laser therapy.

To treat cancer

Class IV laser therapy can also be used to shrink or kill tumors, polyps, or precancerous growths. For patients with cancer, they can be used to relieve cancer symptoms. It can also be used to prevent the spread of tumor cells by sealing lymph vessels.

To improve vision

Laser therapy can be used to improve vision. Studies have shown that laser therapy may be sued to repair a detached retina, hence improving vision.

For cosmetic purposes

In the cosmetic industry and medical practice, class IV lasers can be used to erase birthmarks, sun spots, stretch marks, wrinkles, scars, and blemishes. They can be used to remove hair and tattoos.

Others include:

● To treat hair loss associated with alopecia or aging

● To remove parts of the prostate

● To treat kidney stones

● To close up blood vessels and stop or prevent bleeding

● To close up lymph vessels to prevent swelling

Benefits of Class IV Laser Therapy

The following are benefits offered by class IV therapy. They include:

● Treatment causes less or no pain

● Easily applied

● Drug-free

● Surgery free

● No side or adverse effects

● Non-invasive

● Highly effective for several diseases and conditions

● Affordable

● Non-toxic

● No drug interactions

● Treatment is an alternative option for patients who have undergone other therapies that failed

● Has long-lasting results

Conditions that Class IV Laser Therapy can treat

Class IV laser therapy has been shown to treat numerous health conditions. They include:

● Peripheral neuropathy

● Diabetic neuropathy

● Headaches and migraines

● Neck injury and pain

● Back pain


● Arthritis pain (could be knee, hip, shoulder, etc.)

● Sciatic pain

● Bruises

● Fibromyalgia

● Carpal Tunnel syndrome

● Bursitis

● Bulging, Herniated, or Disc Protrusion

● Plantar Fasciitis

● Epicondylitis (tennis elbow)

● Tendinitis

● Runners knee (patellofemoral pain syndrome)

● Bunion pain

● Diabetic ulcers

● Trigger fingers

● Burns

● Contusions

● Skin conditions like wounds and scars

● Sports injuries

● Auto injuries

● Work-related injuries

● Acute pain related to post-surgical recovery

Class IV laser therapy can successfully conditions that are pain or inflammation-related. Others include medical conditions like kidney stones, bleeding, hair loss, and cancer.

How can a Class IV Laser Treat Neuropathy?

Neuropathy is a condition where there is nerve damage. Several conditions can cause neuropathy, however, the most common cause is diabetes. Untreated and/or poorly managed diabetes results in comprised blood circulation, reducing the supply of oxygen and nutrients to distal body parts. Once nerve damage occurs, it affects how signals are sent and received.

Unlike other tissue, nerves do not repair or regenerate. Nerve damage is irreversible, hence treatment is aimed at slowing down the progression of the neuropathy and relieving symptoms. Symptoms of neuropathy include pain, muscle cramping, bone degeneration, hypersensitivity to light, sound, and touch, and numbness or tingling sensation.

Administering laser therapy for neuropathy can help relieve pain and discomfort associated with the condition. It does this by improving blood circulation to and around the affected body parts. Usually, neuropathy occurs as a result of poor blood circulation to these areas in the first place. Hence, class IV laser therapy helps reverse that, facilitate repair, and improve nerve function by ensuring an increased supply of oxygen and nutrients to nerves in these areas. In the end, laser therapy helps to relieve neuropathic pain and discomfort.

Alongside pain relief, class IV laser neuropathy relieves other symptoms of neuropathy including reduction of inflammation, decrease in muscle cramping, and promotion of wound healing and tissue repair.

Contraindications for Class IV Laser Therapy

The contraindications for the use of therapeutic class IV laser include the following:

Over pacemakers and internal pain pumps

The use of class IV laser for therapeutic purposes over internal pacemakers is contraindicated. This is especially if the laser device uses electrical stimulation as well.

During pregnancy

Like most drugs and therapies, Class IV laser therapy should not be used on pregnant women. This is because high doses of light energy can affect the growing fetus, especially in the first trimester. While recent studies may want to include pregnant women in the therapeutic use of lasers, it is absolutely contraindicated if use will involve regions of the abdomen, low back, and pelvis.

Over the thyroid gland

The thyroid gland is a very delicate structure, and hence treatment targeted towards and around it should be done with proper caution. Studies have shown that high wattages of light radiation could bring about thyroid disorders.

Over glandular tissues

These include the thymus, ovaries, and testicles. It is believed that treatment with lasers may affect the functions of these glands and cause disorders.

In epileptics

Research shows that light (that is, pulsing visible red light with frequencies ranging from 5-10 Hz) can trigger epileptic seizures. Hence, the use of class IV lasers that produce light is contraindicated in people suffering from epilepsy. However, some can still tolerate lower frequencies.

Over growth plates in children

Class IV laser therapy is contraindicated in children, especially over bone growth plates. This however may be changing as recent studies show successful laser treatments in children.

In people living with cancer

Laser therapy could interfere with cancer treatment in patients with cancer, especially those undergoing radiation therapy

After the use of photosensitizing medications

Allowing a patient have class IV laser therapy after he or she has been given or has used photosensitizing medications is a contraindication. Examples of photosensitizing medications include antibiotics such as tetracyclines, sulfonamides, and fluoroquinolones, NSAIDs (non-steroidal anti-inflammatory drugs), and antifungals.


To an extent, class IV laser therapy is contraindicated in patients with diabetes. However, certain studies have shown that class IV laser therapy improved wound healing, and did not affect insulin balance in subjects with diabetes.

Direct or reflected exposure

This is a definite and absolute contraindication. Where is no adequate safety precaution taken, class IV laser therapy should be done or given. Light from class IV lasers can cause instant harm to the eyes, skin, and materials they can get in contact with. If treatment has to be given directly to or near the eye, other alternative forms of treatment should be considered. Do not also administer laser therapy over an injection site.

Others include:

● Over active epiphyses and fontanels

● Over sites of active bleeding

● When patients are wearing metallic objects or accessories such as rings, chains, and wristwatches. These should be removed and kept away or covered before the procedure.

Some of these contraindications have been termed historical. However, with recent studies showing promise, it has been recommended that laser therapy in these conditions and cases should be done with caution.

Recommended Treatment Frequency for Class IV Laser Therapy

Class IV laser therapy sessions last for about 5 to 10 minutes. This, however, depends on which areas are being treated and how large they are. Some conditions may require daily treatment, especially if conditions are characterized by significant pain levels.

Class IV laser therapy yields results within short periods. Usually, acute conditions may require 5-6 sessions for best results. On the other hand, chronic conditions may require more sessions from about 6-12 treatments. However, these are also dependent on other individual factors. There are certain conditions- terminal or life-long illnesses that may require follow-up treatment sessions, for example, 1-2 sessions every month.

The healing process also varies from person to person. Usually, you may notice your skin is dry and peeling off 5 to 7 days after laser treatment. For it to heal, it could take about 10 to 21 days depending on the condition that was treated. Usually, the healed skin is left with redness that fades within two to three months. You could also use oil-free makeup to reduce the redness.

Summary and Conclusion

Laser therapy can be described as a medical treatment that light to bring about health effects in a tissue. It employs a specific wavelength of focused light in medical science to interact with tissues and stimulate the process of photobiomodulation (PBM) or photobiostimulation. This process yields beneficial cellular reactions that result in the following: pain relief and reduction, reduction of inflammation. decrease in muscle cramping and spasm, increase in wound healing and tissue regeneration, immunomodulation, increased cellular metabolism, increased range of motion, and improvement in blood microcirculation.

Hence, class IV laser therapy is the use of high-powered laser light focused and sent into tissues to reduce pain, swelling, and inflammation, and boost healing. Class IV laser due to its high-power output and deeper depth penetration ability has shown to yield better results than cold lasers.

Contraindications however include use over glandular tissue such as the thyroid gland, testicles, ovaries, and thymus gland, over open fontanels and active epiphyses, over pacemakers and internal pain pumps, over growth plates in children, in pregnant woman, in epileptics, people with cancer and diabetes over locally injected sites, and without safety precautions in place.

Both acute and chronic conditions respond well to class IV laser therapy. Pain, swelling, and inflammation are greatly reduced. Affected areas begin optimal functioning within shorter periods compared to medical and surgical therapy. Class IV laser therapy reduces the risk for adhesions and scar tissues which can slow down the healing and recovery process. Tissue regeneration also helps restore function and strength and prevents the reoccurrence of the injury or condition.

Thus, class IV laser therapy is an effective, affordable, and alternative treatment option for acute and chronic pain and its associated symptoms.

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