Introduction
Heat therapy has long been used as an adjuvant for pain relief and treating various musculoskeletal disorders. They are applied through different methods to rehabilitate a wide range of diseases. It can be used before therapy and after therapy to improve the effects.
What Are the Types of Heat Therapy?
The following types of heat therapies are available:
1. Superficial methods.
2. Deep heating methods.
What Are the Superficial Heating Modalities?
In this type of therapy, the heat penetration depth is less than two centimeters.
1. Whirlpool: Water heated at 39 to 40 degrees Celsius is constantly kept whirling in the whirlpool bath. If immersed comfortably, it helps in assisting the active movement of the limb and joints. Patients benefit from overall comfortable healing due to warmth, gravity elimination, and water movement. It helps promote the active efforts of the patient and, therefore, is useful for postoperative mobilization.
2. Infrared: Infrared can be applied through infrared lamps that produce dry heat. It can be used for a duration of 18 to 20 minutes to produce the desired effect. It helps improve localized circulation and nutrition. Infrared relieves superficial pain, relaxes joints and muscles, and softens the superficial subcutaneous tissues and the skin.
3. Hydrocollator: It is made of bentonite clay and other natural fillings. They help relieve inflammatory and joint pain, bruised tissue, congestion, and strains when applied to the skin. They are also used by arthritis patients. Hydrocollator improves blood circulation by enlarging the blood vessels, thereby promoting healing. Athletes who have developed overuse injuries and those in chronic pain may also find this relieving.
4. Hot Packs: Hot packs are the most common heating agents used in rehabilitation. Hot packs transfer heat energy to the body through conduction. Superficial heat usually produces temperature elevation in the underlying tissues to a depth of one centimeter. Adipose tissue acts as an insulating layer, decreasing heat depth. Commercial hot packs are canvas, usually filled with a hydrophilic substance, that is immersed in hot water with a temperature of 77 degrees Celsius. These hot packs can retain heat for up to 30 minutes. With superficial heat, local metabolism is increased, and local vasodilatation with hyperemia occurs. Initial vasoconstrictors are produced in deep tissue layers, followed by vasodilation. Hot packs also promote muscle relaxation as well as sedation of sensory nerve endings.
Indications: It can be used in subacute or chronic traumatic and inflammatory conditions and can also be used as a preheating method before electrical stimulation.
Contraindications: It cannot be used in the following conditions:
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Patients with acute inflammatory conditions.
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Patients who have a fever and high temperature.
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Patients with possible metastases of malignancies.
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It cannot be applied to areas having active bleeding.
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Patients who have received radiation therapy.
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Patients with peripheral vascular disease.
5. Paraffin Wax: Paraffin is another form of a heat-delivering method used to treat difficult areas like the distal extremities. A paraffin bath is a container holding a mixture of paraffin (approximately five pounds) and mineral oil (approximately one pint). The melted wax temperature is maintained at 125 to 127 degrees Fahrenheit. Because of the low specific heat, a higher temperature of the paraffin can be tolerated compared to water. Paraffin and oil together not only produce heat but also help soften skin.
Indications: It is used in patients having chronic arthritis of the hands or feet and in patients with subacute and chronic traumatic inflammatory conditions.
Contraindications: Paraffin bath is contraindicated in wounds that are open and in lesions that are infected. It is not used in acute inflammatory joint disorders because interscapular heating may accelerate the destruction of articular cartilage.
What Are the Deep Heating Modalities?
In this type of therapy, the depth of penetration of heat is more than two centimeters.
1. Microwave Diathermy: Microwaves are electromagnetic radiation and will help deliver short pulses of high-intensity microwaves. It helps improve membrane permeability, collagen synthesis, pain threshold, and scar tissue resolution, relieving joint adhesions. It also helps in wound healing and scar remodeling.
2. Shortwave Diathermy: This produces deeper tissue heating for up to 30 to 50-millimeter depth through electromagnetic induction by high-frequency currents. It can never be used in acute injuries. This is ideal in deeper chronic pain joints and helps improve the concentration of white blood cells and antibodies in the application area. It helps reduce deeper localized pains due to neuromuscular pathology.
3. Laser: Low-frequency light waves produce photochemical reactions within the tissue cells. It helps relieve acute as well as chronic pain due to muscular and neuropathic injuries.
4. Ultrasound: Ultrasound is a deep heating agent commonly used in rehabilitation. Deep heating agents are capable of causing increased temperatures in tissues up to three to five centimeters deep. Ultrasound can be used as a pulsed wave, in which the intensity is periodically interrupted. Ultrasound produces increased extensibility of collagen fibers, decreased joint stiffness, decreased muscle spasm, pain modulation, increased blood flow, and a mild inflammatory response.
Indications: It can be used for soft tissue shortening in conditions like joint contractures and scarring. Ultrasound can be used in subacute and chronic inflammatory conditions. It can be used in conditions such as muscle spasms, trigger areas, muscle guarding, and neuroma.
Contraindications: Ultrasound should be avoided in the following situations:
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Patients who have insufficient arterial circulation.
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Injuries that have active bleeding.
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Avoided in areas like the eyes and spinal cord as it may produce cavitation.
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It should be avoided in pregnant women.
Conclusion
Thermotherapy is an easy and cost-effective method to help cure subacute or chronic inflammatory conditions. It helps in relieving chronic pain and muscle spasms. For patients with locomotion disabilities, exercise can be taught inside the water, and the joints can be moved to the end range of motion without any discomfort. It will provide a wide range of neuromuscular effects and helps in the development of tissue extensibility when used in the right way.
