Complementary Adjuncts for Managing Foot and Ankle Pain

Complementary Adjuncts for Managing Foot and Ankle Pain

Gerard Limerick

Vivek Sindhi

Shravani Durbhakula


The use of adjunctive and complementary treatments for managing foot and ankle pain has been around for many years. At the most basic level, most of these treatments can be classified by modality: heat, cold, or electricity. The mechanism of action for treatments that utilize heat or cold typically involves conduction, conversion, convection, or evaporation. The use of electricity for therapeutic benefit, or electrotherapy, involves the stimulation of a nerve or muscle using superficial electrodes. Most of the discussion in this chapter will center around treatments that utilize these 3 modalities. It is important to note that many of the treatments discussed in the following pages have been around for several decades (in some cases, a few centuries). Additionally, the specifics of how these treatments are administered are largely unchanged over the last several years. As such, there is a dearth of current trials evaluating the mechanism of action and/or efficacy of these treatments. While there is not much evidence for these treatments in medical literature, they are generally safe (specific contraindications will be discussed in each section), accessible and low-in-cost, and therefore, may be used liberally by the practitioner on a case-by-case basis as seen fit.


Heat provides analgesia through a few different pathways. Cutaneous thermoreceptors are activated maximally between 99°F and 104°F. When activated, they reduce transmission of pain signals to the lateral spinothalamic tract through competitive firing (see Melzack and Wall’s Gate Theory in the SCS chapter). Heat causes increased local blood flow and circulation, which may help remove inflammatory metabolites.1 Heat also reduces pain by relaxing skeletal muscle.2,3 There is some evidence that heat’s ability to induce muscle relaxation may be due to a local decrease in muscle sympathetic nerve activity.4 Heat is effective in treating both subacute and chronic pain. However, it may worsen inflammation and should be avoided in the setting of acute tendinitis, arthritis, or sprain. It should also be avoided in the setting of hemorrhage or bleeding diathesis, impaired circulation or sensation, malignancy, cemented hardware, cognitive deficits (or any such global condition that would prevent reliable pain reporting), skin anesthesia, open wounds, and infection.


Conduction is the transfer of thermal energy through direct contact. Modalities that utilize
conduction to transfer heat, heat tissue up to 1 cm in depth below the skin.5 Superficial heat is useful in treating subacute and chronic pain, such as that caused by muscle spasm, contusion or strain, ankle ligament sprains, chronic tenosynovitis, or osteoarthritis. The most common modality for superficial heat is the hydrocollator pack—a canvas pouch that is filled with a petroleum distillate. The hydrocollator packs are stored in water baths set to 170°F. They are removed from the bath with tongs or scissor handles and are wrapped in 6 layers of towels. They may be applied to the foot or ankle for 15 to 20 minutes. There is a small risk of burns, which is higher in elderly patients. To reduce this risk, the skin should be checked intermittently, particularly during the first treatment. Also, exercise caution if placing the foot on top of the pack, as this may force the hot pack contents out of the pack and into contact with the skin.

Another commonly used heat treatment that uses conduction is the paraffin bath. It is particularly useful for foot and ankle pain management, as it ensures uniform delivery of heat to small joints (eg, think osteoarthritic toes). In a randomized-controlled trial, patients who were experiencing posttraumatic ankle stiffness and were subsequently treated with paraffin baths showed improved ankle ROM at 10 weeks, when compared to other posttraumatic patients who did not receive treatments with paraffin baths.6 The paraffin bath should be set to 126°F. The foot is dipped into the paraffin bath for a couple seconds and then removed for a few seconds to allow the paraffin to harden slightly. This is repeated 5 times, so that the patient’s foot has a total of 6 layers of paraffin. The first layer is the most important and should reach highest on the patient’s limb. After the first layer of paraffin has formed, each subsequent layer should reach a little lower on the limb than the previous layer to ensure adequate dissipation of heat and prevent burns. After the paraffin layers have been placed, the paraffin is wrapped, from deep to superficial, in paper towels, plastic bags, and towels to maintain the heat. The foot may remain wrapped for 20 to 30 minutes, before all materials are removed.


Convection is the transfer of thermal energy through the movement of a liquid or gas. Therapies that utilize convection to transfer heat, much like conduction, also provide superficial heat to the affected area. When water is used to transfer heat through convection in the setting of pain-relieving modalities, this is referred to as hydrotherapy. In addition to transferring heat, hydrotherapy may also help moisten the soft tissue and provide mechanical support.7 A whirlpool is the most commonly used option for hydrotherapy. For treatment of the feet, the temperature should be set at 98°F to 110°F. The foot should be immersed for 15 to 20 minutes. An added benefit of using the whirlpool for hydrotherapy is the jet flow. The massaging effect of the jet flow may help further increase muscle relaxation and local circulation. If the jet flow is being utilized, it should be 6 to 9 in from the foot.


Conversion is the transformation of energy from one form to another. For the purposes of treating pain, this typically refers to the transformation of acoustic or electromagnetic energy to heat. Conversion is useful for heating deep tissue, 3 to 5 cm below the skin, without excessively heating skin or subcutaneous fat.2,5 Heating deep tissue (eg, ligament, tendon, muscle, joint capsule) using conversion is known as diathermy. The diathermic modalities that are most frequently used are ultrasound, shortwave, and microwave.


Ultrasound waves are acoustic waves with frequencies above the upper limit of human hearing. In the machines used in clinical settings, ultrasound waves are created when electrical energy is passed through a piezoelectric crystal in the transducer.8 Therapeutic ultrasound has a frequency range of 0.75 to 3 MHz. Lower frequency therapeutic ultrasound (about 1 MHz) is primarily absorbed at 3 to 5 cm of depth, whereas higher frequency therapeutic ultrasound (about 3 MHz) is more useful for surface lesions.9

A complete review of ultrasound physics is beyond the scope of this chapter. However, a few key concepts are worth noting here. Attenuation is the loss of ultrasound energy as the beam travels through tissue. Energy is lost from the beam as it, both, scatters through tissue and is absorbed by structures. All structures do not absorb energy equally. Structures that have high-attenuation coefficients (bone has the highest) absorb the most energy at or near the surface of the structure.10 As bone has a high energy coefficient, therapeutic ultrasound preferentially creates the most heat near bony surfaces. This produces local hyperemia and enhances the extensibility of ligaments, tendons, and joint capsules.3 In addition to the therapeutic benefits conferred from the local heat, ultrasound has been found to stimulate fibroblast activity, thereby enhancing collagen production and noncollagen protein synthesis.11 More studies are needed to further investigate the efficacy of therapeutic ultrasound for foot and ankle pain.

The general considerations for the safe and appropriate use of therapeutic heat apply here. Additionally, therapeutic ultrasound should not be used over nerves or epiphysis. Ultrasound is typically applied by moving the probe in the area of interest (typically about 4 sq in) in a circular or longitudinal manner for 5 to 10 minutes. Keeping the probe in one stationary place should be avoided to prevent the creation of standing waves or local hot spots.3 Ultrasound may also be applied through the immersion method. This method is particularly suited for treating irregular surfaces, such as the foot or ankle. In the immersion method, the foot is placed in a container filled with degassed water (produced by allowing water to sit for several hours untouched or using a commercial vacuum device). The probe is held 0.5 to 3.0 cm away from the skin and moved around the area of interest without touching the skin.


Shortwave diathermy produces heat by converting electromagnetic energy to thermal energy. Heat is generated by oscillating high-frequency electrical and magnetic fields to move ions, rotate polar molecules, and distort nonpolar molecules in body tissues.3 Shortwave diathermy can be applied by placing the foot between capacitor electrodes or by wrapping inductor cable electrodes around the ankle and foot. Towels should be placed between the ankle/foot and electrode to absorb moisture and avoid focal hot spots. If using cable electrodes, crossover of the coils should be avoided to prevent overheating. A 20 to 30 minute total treatment time is typically sufficient.

Shortwave diathermy may be preferable to ultrasound if the painful area is the interior of the ankle joint due to the high-attenuation coefficient of bone. Additionally, the previously listed standard contraindications for applying heat are valid here. As in ultrasound, the epiphysis should be avoided, as this may cause growth abnormalities. If there is significant foot/ankle edema, shortwave diathermy is contraindicated, as the electromagnetic waves may preferentially heat water.


Microwave diathermy, like shortwave diathermy, also produces heat by converting electromagnetic energy to thermal energy. However, microwave diathermy utilizes a shorter frequency than shortwave diathermy. Additionally, microwave diathermy utilizes a lesser extent of the magnetic field than shortwave diathermy. Microwave diathermy does not penetrate as deeply as ultrasound or shortwave and is therefore best suited for areas with low subcutaneous fat.3 The applicator is applied directly to the skin at the target site, 20 to 30 minutes of therapy per session is sufficient.

Microwaves preferentially heat water, so microwave diathermy may be preferable for heating tissue with high water content, such as muscle. Contraindications for microwave diathermy include general heat contraindications, as well as those previously listed for shortwave diathermy. Microwave diathermy is used less by many therapists, as there have been epidemiologic studies that suggest an increased risk of miscarriage in pregnant therapists who treat patients with microwave diathermy.12


Infrared is mentioned last in this segment, as it occupies a fairly unique position in the
armamentarium of therapeutic heat options. It utilizes electromagnetic energy, but unlike the other therapies that utilize electromagnetic energy, it has a maximum penetration of 1 cm. Despite this limitation, the unique advantage of infrared therapy, as compared to other therapies that provide superficial heat, is that it is able to transfer heat without directly contacting the skin.

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Sep 8, 2022 | Posted by in ORTHOPEDIC | Comments Off on Complementary Adjuncts for Managing Foot and Ankle Pain
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