This chapter focuses on the physical medicine techniques used to treat patients in pain. At the conclusion of reading this chapter the reader will have a thorough understanding of physical medicine techniques and how they fit into the multidisciplinary comprehensive treatment of patients with pain. Although the physical medicine approach can help decrease pain and increase function, if combined with medication, behavioral modification, cognitive modification, and sometimes interventions, the results can be much more dramatic.
In the third edition of this text, Linchitz and Sorell defined physical medicine and rehabilitation and the role of the physiatrist. They noted that “Physical medicine and rehabilitation have traditionally been the medical specialty that oversees and prescribes the application of physical modalities to treat disease and disorders, including the rehabilitation of patients with pain. The physiatrist, whose primary perspective is typically one of the functions, is an expert on the musculoskeletal and locomotor systems and is knowledgeable about how to use physical agents and how to coordinate the rehabilitation team. As part of the multidisciplinary medical team, the physiatrist participates in the evaluation and treatment of those individuals with pain.”
However, there are not enough physiatrists to treat all patients with pain. Therefore, all physicians need to understand the rationale, indications, contraindications, and prescription of physical medicine techniques and their appropriate use. Many of these techniques can be used for acute, subacute, and chronic pain. However, with progression to more chronic pain, techniques should be more active and less passive and more behavioral and cognitive in nature. Although many of these techniques will help decrease pain, the long-term goal should be to increase function despite the presence of the pain syndrome.
Approach to Treatment
Patients with pain can be evaluated and treated by individual physicians and therapists. This type of approach is more often used and successful in patients with acute or subacute pain. However, as the pain becomes more chronic and includes psychosocial and vocational issues, a multidisciplinary or interdisciplinary approach is recommended.
Although the terms multidisciplinary and interdisciplinary are often used interchangeably, multidisciplinary more formally refers to collaboration among members of different disciplines (including various medical specialists and therapists), managed by a leader who directs a range of ancillary services. Interdisciplinary describes a deeper level of consensus-based collaboration in which the entire process (i.e., evaluation, goal setting, and delivery of treatment) is orchestrated by the team, facilitated by regular face-to-face meetings, and primarily delivered at a single facility. The interdisciplinary team is commonly led by a pain specialist and includes physical and occupational therapists; pain psychologists; relaxation training experts; vocational, rehabilitation, and therapeutic recreational specialists; social workers; and nurse educators. The role of these team members is discussed later in this chapter.
It should be noted that comprehensive reviews of the cost-effectiveness and efficacy of interdisciplinary programs have demonstrated significant improvements in return to work, increased function, reduced health care use, and closure of disability claims. These comprehensive programs have also shown clear benefits over conventional management with regard to decreasing pain behavior and improving mood. The interdisciplinary model provides ongoing communication among all members of the treatment team, which helps facilitate patients’ care while they progress to behavioral, cognitive, and active therapy.
Role of the Therapy Team
Ideally, a pain program should be comprehensive and interdisciplinary. Typically, the team is led by a physician and consists of physical therapists, occupational therapists, and often recreational therapists, dieticians, and psychologists. Combined assessment by these professionals is used to devise a comprehensive approach to allow the patient to benefit maximally, reintegrate fully into life, and have as few restrictions as possible.
It is important that realistic goals be set before therapy begins. Such goals include but should not be limited to decreasing muscle tightness, increasing strength in areas of muscle weakness, increasing general aerobic conditioning, and improving ease in performance of activities of daily living. In general, one wants to first restore flexibility and then increase strength and develop endurance. Completely removing the pain may not be a realistic goal of therapy, but increased function should be. Box 46.1 lists the goals of therapy to be accomplished.
Restore biomechanical dysfunction.
Improve strength.
Improve posture.
Improve gait symmetry.
Improve general aerobic conditioning.
Improve efficiency of activities of daily living.
Decrease edema.
Instruct patients to monitor pain response and to pace activity.
Use back or joint conservation techniques.
Sometimes, the distinction between physical and occupational therapists is lost. Physical therapists focus on the strength, flexibility, and coordination of large muscle groups. They assess and help in developing strength and flexibility of the legs, pelvic girdle, and trunk and address mobility by ambulation. They also train patients in back and body mechanics. Occupational therapists focus on fine and gross motor strength, flexibility and coordination of the hands, and activities of daily living. For pain patients, they are also good in teaching conservation techniques. They can help patients in their work by instructing them in ergonomics, work simplification, and energy conservation. Another important aspect that they address is proper posture, which can result in a significant reduction in pain if put into practice daily. The roles of physical and occupational therapists are presented in Box 46.2 .
Physical Therapists
Loss of flexibility
Strength and weakness of trunk and limb muscles
Core strengthening
General aerobic conditioning
Balance and coordination
Contractures
Assisted mobility
Occupational Therapists
Joint conservation techniques
Work simplification techniques
Back conservation
Posture
Energy conservation techniques
Activities of daily living and self-care
Edema control
Recreational therapists assist in providing pleasurable outlets to help maintain physical conditioning. Instead of prescribing a boring set of home exercises, incorporating pleasurable activities that are also distracting often increases the patient’s interest and cooperation. The psychologist’s role is to identify factors that may be complicating the pain experience and help the patient deal with the process in a better way. There are many useful tools and tests to help the psychologist determine other confounding factors so that the patient’s functioning can be increased maximally. These include the Minnesota Multiphasic Personality Inventory, Beck Depression Inventory, Oswestry scale, Symptom Checklist 90, and McGill Pain Questionnaire. The psychologist, working alone or with the team, can encourage pain reduction by teaching the patient stress management, relaxation, and self-monitoring techniques. Stress reduction can be achieved through cognitive-behavioral therapy.
The physician’s role is mainly to lead the team in complete management of the patient. This includes making sure that there is no disease process that might be causing the pain and, if present, that there is no other treatment or intervention that should be pursued before initiating therapies. It also includes monitoring safe participation in physical rehabilitation while optimizing medication management. If it is thought that the patient could benefit from interventions, it is easier if this is done before initiating a comprehensive rehabilitation program.
Physical conditioning programs use a cognitive-behavioral approach plus intensive physical training that includes aerobic capacity, muscle strength and endurance, and coordination. These approaches can be work related, given and supervised by a physiotherapist or multidisciplinary team, and seem to be effective in reducing the number of sick days for some with chronic back pain when compared with usual care.
Role of the Therapy Team
Ideally, a pain program should be comprehensive and interdisciplinary. Typically, the team is led by a physician and consists of physical therapists, occupational therapists, and often recreational therapists, dieticians, and psychologists. Combined assessment by these professionals is used to devise a comprehensive approach to allow the patient to benefit maximally, reintegrate fully into life, and have as few restrictions as possible.
It is important that realistic goals be set before therapy begins. Such goals include but should not be limited to decreasing muscle tightness, increasing strength in areas of muscle weakness, increasing general aerobic conditioning, and improving ease in performance of activities of daily living. In general, one wants to first restore flexibility and then increase strength and develop endurance. Completely removing the pain may not be a realistic goal of therapy, but increased function should be. Box 46.1 lists the goals of therapy to be accomplished.
Restore biomechanical dysfunction.
Improve strength.
Improve posture.
Improve gait symmetry.
Improve general aerobic conditioning.
Improve efficiency of activities of daily living.
Decrease edema.
Instruct patients to monitor pain response and to pace activity.
Use back or joint conservation techniques.
Sometimes, the distinction between physical and occupational therapists is lost. Physical therapists focus on the strength, flexibility, and coordination of large muscle groups. They assess and help in developing strength and flexibility of the legs, pelvic girdle, and trunk and address mobility by ambulation. They also train patients in back and body mechanics. Occupational therapists focus on fine and gross motor strength, flexibility and coordination of the hands, and activities of daily living. For pain patients, they are also good in teaching conservation techniques. They can help patients in their work by instructing them in ergonomics, work simplification, and energy conservation. Another important aspect that they address is proper posture, which can result in a significant reduction in pain if put into practice daily. The roles of physical and occupational therapists are presented in Box 46.2 .
Physical Therapists
Loss of flexibility
Strength and weakness of trunk and limb muscles
Core strengthening
General aerobic conditioning
Balance and coordination
Contractures
Assisted mobility
Occupational Therapists
Joint conservation techniques
Work simplification techniques
Back conservation
Posture
Energy conservation techniques
Activities of daily living and self-care
Edema control
Recreational therapists assist in providing pleasurable outlets to help maintain physical conditioning. Instead of prescribing a boring set of home exercises, incorporating pleasurable activities that are also distracting often increases the patient’s interest and cooperation. The psychologist’s role is to identify factors that may be complicating the pain experience and help the patient deal with the process in a better way. There are many useful tools and tests to help the psychologist determine other confounding factors so that the patient’s functioning can be increased maximally. These include the Minnesota Multiphasic Personality Inventory, Beck Depression Inventory, Oswestry scale, Symptom Checklist 90, and McGill Pain Questionnaire. The psychologist, working alone or with the team, can encourage pain reduction by teaching the patient stress management, relaxation, and self-monitoring techniques. Stress reduction can be achieved through cognitive-behavioral therapy.
The physician’s role is mainly to lead the team in complete management of the patient. This includes making sure that there is no disease process that might be causing the pain and, if present, that there is no other treatment or intervention that should be pursued before initiating therapies. It also includes monitoring safe participation in physical rehabilitation while optimizing medication management. If it is thought that the patient could benefit from interventions, it is easier if this is done before initiating a comprehensive rehabilitation program.
Physical conditioning programs use a cognitive-behavioral approach plus intensive physical training that includes aerobic capacity, muscle strength and endurance, and coordination. These approaches can be work related, given and supervised by a physiotherapist or multidisciplinary team, and seem to be effective in reducing the number of sick days for some with chronic back pain when compared with usual care.
Basic Management Considerations
Clinical Evaluation
Patients with acute or chronic pain may be referred for physical medicine evaluation and treatment as a component of a multidisciplinary management approach or for certain specific treatments. Before initiating treatment, it is important to perform a history and physical examination ( Chapter 13 ), review the medical records to identify factors contributing to the patient’s complaints, and assess the impact of pain on the patient’s functioning. Contraindications to physical medicine treatments and precautions for treatment should be identified. A careful and thorough history and physical examination also help establish trust between the clinician and patient and facilitate consensus with treatment recommendations.
History
A detailed history is obtained by interviewing the patient and reviewing questionnaires and medical records. It is important to obtain information about the time course, intensity, and location of the pain, as well as relieving and exacerbating factors. The functional state of the patient before onset of the problem and the current functional level should be determined to establish a baseline and guide expectations for improvement. The patient’s experiences and responses to previous diagnostic and therapeutic interventions should be noted because they may predict responses to future treatment. Medical conditions that can affect or be affected by physical medicine treatments should be identified. It is also important to obtain information on medications, coexisting psychological and psychiatric disorders, substance abuse or addiction, and involvement in litigation because these factors can affect the patient’s response to treatment.
Physical Examination
A complete physical examination with a focus on the neurologic and musculoskeletal systems should be performed. Active and passive joint range of motion (ROM), muscle bulk, strength, and sensation should be assessed and documented. Findings in the involved area should be compared with those on the asymptomatic side when possible. Patterns of pain and sensory loss can provide clues to the site of nervous system pathology or dysfunction. Signs of vasomotor instability, such as changes in skin temperature and alterations in hair, nails, or perspiration, may indicate autonomic dysfunction. Pain may limit testing of ROM, strength, and sensation; if this is the case, it should be noted. Reflex testing can be particularly helpful because it is one of the more objective parts of the examination. Abnormal or asymmetrical reflex responses may indicate dysfunction or pathology of the nervous system. Evidence of previous surgery or injury should be noted.
A patient’s gait, posture, and movement can provide diagnostic clues to the source and severity of the pain. It is helpful to observe the patient and form a general impression before carrying out the formal physical examination. Inconsistencies between the patient’s complaints and behavior should be noted.
Functional Evaluation
A functional evaluation should be performed on pain patients before, during, and after completion of any treatment or functional restoration program. Functional evaluation may range from direct observation of function by the clinician to formal functional capacity evaluation (FCE) performed by trained health care personnel.
Functional assessment can provide additional useful information because tests of pain perception, psychological distress, and self-perception of abilities and limitations do not accurately assess a person’s physical capacity for work. Physicians and patients often have great difficulty estimating functional limitation and physical ability.
FCEs have existed in one form or another since the 1940s, although their use and application have changed over time. They are primarily used in industrial medicine and in legal and disability settings. Reasons for ordering an FCE include making disability determinations, setting goals and planning treatment for industrial rehabilitation, monitoring progress through industrial rehabilitation, determining a person’s readiness to return to work after injury, performing pre-employment evaluation, and determining case closure.
Most FCE protocols include some or most of the following components: an interview, record review, self-administered questionnaire, psychological test battery, musculoskeletal evaluation, functional testing, validation of sincerity of effort, and comparisons to specific job requirements. Functional testing may include material handling, specific tasks, holding static postures, and repetitive task performance. A job analysis should be done before administration of an FCE because measurement of work capacity is specific to the demands posed by a job.
There are scientific and practical limitations associated with FCEs with regard to standardization, validity, and reliability. They have not necessarily been shown to predict return to work. However, they may be helpful in charting changes in function, comparing functional disparities with job demands, identifying nonmedical factors influencing the ability to work, and serving as a tool to guide work restrictions for patients returning to work or for initial therapy prescriptions for patients beginning a rehabilitation program.
Psychological Evaluation
A psychological evaluation should be considered when the pain is resulting in significant impairment in psychological, vocational, or social functioning. Such evaluations can determine the emotional, cognitive, behavioral, social, or vocational factors that could be affecting the patient’s perception of pain.
It is important that the psychological evaluation of a patient in chronic pain be conducted by a clinician who is sensitive to and knowledgeable about the psychological aspects of chronic pain. It should be appreciated that many chronic pain patients may be defensive about a psychological referral and are more likely to be evaluated if they are provided with an appropriate rationale and explanation for the referral. This topic is discussed further in Chapter 16 .
Electrodiagnostic Testing
Electrodiagnostic testing encompasses nerve conduction studies (NCSs) and electromyography (EMG), which provide information about the peripheral nerves and muscles, and evoked potentials, which are used mainly to assess the central nervous system ( Fig. 46.1 ). Chapter 14 presents a more detailed discussion of the role of electrodiagnostic testing.
Electrodiagnosis can play an important role in identifying an underlying problem in a patient with a pain disorder. It helps not only in diagnosis but also in determining the chronicity and severity of the condition and can even assist in prognosis. Electrodiagnostic testing has another advantage when dealing with a pain patient who has signs of radiculopathy. Because disk bulges seen with magnetic resonance imaging (MRI) may be found routinely at many levels, EMG can help determine whether one of these disk bulges is actually producing nerve damage. In addition, this test may be helpful in patients who have radiculitis with no structural disk herniation and often normal results on MRI. EMG has also been shown to help in making the diagnosis of spinal stenosis but does not predict future pain. However, it has also been shown that the findings on EMG do not necessarily correlate with severity of the pain.
Most physicians will perform NCSs and EMG together in the same session. The NCSs usually involve testing of sensory and motor nerves and sometimes reflex studies. Common nerves studied in the lower extremity include the sural, tibial, and deep peroneal and, in the upper extremity, the median, ulnar, and radial nerves. The facial and trigeminal nerves are tested less often.
When performing a motor NCS, the active electrode is placed over the muscle belly, the reference electrode is placed over the tendon insertion, and the nerve is stimulated at a fixed distance from the muscle. F-wave responses can also be recorded during motor studies; they can indicate the integrity of the entire motor nerve.
When performing a sensory NCS (usually done antidromically), the active and reference electrodes are placed over a distal nerve segment and the nerve is stimulated proximally ( Fig. 46.2 ). The EMG study can be done with concentric or monopolar needles. There are two parts of EMG—evaluation of spontaneous activity and evaluation of motor unit action potentials (MUAPs). Typically, in neurogenic conditions the electromyographer will notice fibrillation potentials or positive sharp waves (PSWs) with spontaneous activity, which indicates instability of the muscle fiber membrane, enlarged MUAPs, and decreased MUAP recruitment.
Radiculopathy
The sensitivity of EMG in the diagnosis of radiculopathy is lower than that of MRI, but its specificity is significantly better. EMG helps identify not only which nerve is involved but also the severity and chronicity of the lesion. It is important to remember that in radiculopathy, sensory NCS findings are normal because compression of the nerve root usually occurs proximal to the dorsal root ganglion, which therefore spares it. In S1 radiculopathy, the H-reflex is often prolonged.
Diagnosis of radiculopathy relies primarily on the electromyogram. With subacute, single–nerve root involvement, one should find denervation (fibrillation potentials, PSWs, or both) in two or more muscles of that myotome, involvement of the paraspinal muscles at the same level, and no denervation in other myotomes. It usually takes about 3 to 4 weeks for denervation to appear in the extremity muscles, but there may be earlier signs, such as decreased recruitment of motor units in muscles innervated by the involved root or signs of denervation in the paraspinal muscles. A more detailed discussion is presented in Chapter 14 , so Table 46.1 summarizes abnormalities in some common disorders found by only NCSs and EMG.
| Disorder | Motor Study | Sensory Study | EMG | F and H Waves |
|---|---|---|---|---|
| Radiculopathy | Usually normal; if severe, may have a reduction in amplitude | Normal | Fibs and PSWs in muscles supplied by that root | Mild to moderate prolongation of H and F response latencies |
| Axonal polyneuropathy | Reduced amplitude in distal muscles | Reduced amplitude of distal nerves | Fibs and PSWs in distal muscles | Mild to moderate prolongation of H and F response latencies |
| Demyelinating polyneuropathy | Slowing of CV, prolongation of distal latency | Reduced amplitude and CV | Fibs, PSWs, variable reinnervation; reduced recruitment of motor units | Severe prolongation, absence of F and H responses |
| Compression neuropathy | Focal slowing of CV across the affected segment if mild, reduction in amplitude if severe | Slowing of CV across the affected segment, reduction in amplitude if severe | Fibs and PSWs in muscles supplied by that nerve | Mild prolongation in F responses |
| Plexopathy | Reduced amplitude in muscles supplied by affected fibers | Reduced amplitude in sensory nerves traversing the affected part of the plexus | Fibs and PSWs in muscles supplied by affected fibers | Mild to moderate prolongation of F and H latency |
| Mononeuropathy multiplex | Focal “axonal” lesions of multiple nerves with markedly decreased amplitude | Reduced or absent responses in affected nerves | Marked abnormalities in muscles supplied by the affected nerve | Mild prolongation or absence of H and F responses |
Reflex Sympathetic Dystrophy
Despite the involvement of sympathetic nerves, electrophysiologic studies do not reveal specific abnormalities unless there is an associated nerve injury. One study has suggested relative reductions in the amplitude of the sympathetic nerve fiber function in the affected area as compared with the affected extremity.
Treatment Goals
The etiology of the pain syndrome should be determined from a medical and psychosocial point of view, and if possible, the location of the “pain generator” should be identified. Attempts to decrease or eliminate pain generators are important and should be carried out first, followed by consideration of other treatment options.
The goals of treatment center on moderating pain, increasing function, decreasing psychosocial issues, and reducing health care use. These objectives can be achieved by modifying pain medication and pain behavior, decreasing reliance on medical care, increasing activity through exercise, and dealing with psychological and vocational issues.
The Fordyce model of behavioral modification is useful in the treatment of patients with chronic pain syndromes. The goal in these patients is not to cure the pain but to interrupt the pain behavior reinforcement cycle by rewarding healthy behavior and setting appropriate goals for the patient. Such goals include a reduction in the use of medications, modulation of the pain response, increased activity, and reduction in pain behavior.
Role of Medications
Pain commonly limits participation in a physical therapy or rehabilitation program. Adequate pain management is an important component of rehabilitation. Many patients may be free of pain at rest and have incident pain provoked by activity or movement. Analgesic medications that are not timed to the patient’s pain may lead to overdosing at rest and underdosing during pain or activity. Simple measures such as taking oral analgesic medications 30 to 60 minutes before the onset of therapy or other activity that incites pain can provide satisfactory pain relief and increase the success of therapy.
In the postoperative setting, patients may benefit from multimodal analgesic techniques, including the use of combinations of analgesic medications and regional-peripheral nerve blocks. Parenterally administered analgesic medications are more effective for treating severe, acute, or rapidly changing pain because of their rapid onset of action and ease of dose titration. Patient-controlled analgesia allows self-titration of analgesic medication to an individual’s pain and activity level.
Patients with different types of pain—neuropathic, musculoskeletal, inflammatory—will benefit from medications that address the different causes of pain. Some patients have comorbid conditions that can increase the experience of pain, such as soft tissue inflammation, muscle spasms, or depression. The concurrent use of medications to treat these coexisting symptoms may help reduce the degree of pain experienced.
Role of Physical Modalities
Physical modalities are physical agents and techniques used to produce a therapeutic response. There is a long history of use of physical modalities to treat pain that dates back to ancient human prehistory and civilizations. Physical modalities and techniques commonly used to relieve pain include therapeutic heat and cold, hydrotherapy, ultrasound, electricity, and traction. Evidence-based guidelines regarding the use of physical modalities for acute and musculoskeletal pain have been published.
It is important to realize that physical modalities do not eliminate pain by themselves and generally should not be prescribed as stand-alone treatments. Rather, they are best used as adjunctive treatments to an active exercise program. Modalities that the patient can safely use at home, such as hot and ice packs and transcutaneous electrical nerve stimulation (TENS), are more useful for chronic pain management. Modalities that require health care personnel to administer are best reserved for those with acute pain syndromes or intermittent exacerbations of chronic pain.
Before prescribing or administering a physical modality, an accurate diagnosis needs to be established and the goals of treatment determined. It is important to be aware of contraindications to the use of a specific modality. Precautions that need to be taken should be specified in the prescription.
Physical Modalities
Therapeutic Heat
Heat is one of the oldest physical modalities used to relieve and reduce pain. In addition to relief of pain, heat elicits other physiologic responses in local tissues that may be therapeutic, including increased blood flow, increased connective tissue extensibility, decreased muscle spasm, decreased joint stiffness, and reduced edema. Heat may also have a modulating effect on pain at the spinal and supraspinal levels. There is evidence that heat wrap therapy provides a short-term reduction in acute or subacute low back pain.
Clinicians considering the use of therapeutic heat should first decide whether superficial or deep heat is required and then choose the appropriate heating modality. Superficial modalities include hot packs, heating pads, heat lamps, paraffin and whirlpool baths, and fluidotherapy. Deep heating agents include ultrasound, short wave, and microwave.
Contraindications to therapeutic heat are listed in Box 46.3 . The risk for burns from external heat sources is real, and physicians should always write precautions to monitor for burns when heat is prescribed.
Insensate skin
Atrophic skin
Inability to communicate or respond to pain
Acute inflammation
Malignancy
Ischemia
Growth plates
Peripheral vascular disease
Demyelinating disease
Superficial heat is delivered primarily by conduction, convection, and conversion. Modalities that transfer heat by conduction include hot packs (hydrocollator packs), heating pads, and paraffin baths. These heating modalities generally penetrate to depths of less than 2 cm from the skin. Skin and subcutaneous tissue temperatures are increased by 5° C to 6° C after 6 minutes and maintained for up to 30 minutes after application.
A heating duration of 15 to 30 minutes may be necessary to increase muscle temperature by 1° C at depths of up to 3 cm. A 1.2° C increase in knee intra-articular temperature has been demonstrated after superficial heat application.
Hydrocollator packs are hot packs that contain a silicate gel product encased in canvas. These packs are heated and stored in thermostatically controlled water baths. Before application, the packs should be wrapped in several layers of towels and excess water allowed to drain off. To minimize the risk for burns, hot packs should be placed on the patient rather than under the patient because body weight and pressure impair circulation and dissipation of heat from the heated area.
Heat lamps provide superficial heating through conversion. Heat is generated in tissue through induction of molecular vibration by infrared waves emitted by the lamps. The degree of heating is a function of lamp wattage, angle of application, and distance to the body part. Radiant heat from lamps may be preferred when heating a diffuse area is required or when direct contact of a heating pad with the skin is not desirable.
Paraffin baths are a superficial heat modality commonly used for the treatment of distal extremity pain and stiffness from rheumatoid arthritis, osteoarthritis, and other connective tissue diseases. The two primary methods of application are dip and wrap and dip and immerse. The former is more popular; it consists of dipping and removing the body part from the paraffin bath 8 to 10 times, followed by wrapping to assist in retention of heat. The paraffin–mineral oil mixture used should be heated in a bath with a thermostatically controlled heater.
Hydrotherapy is the use of water for medical purposes; it includes treatments as diverse as aquatic therapy and wound care. Patients with painful musculoskeletal conditions can often exercise more easily in water because of reduced weight bearing and additional support. Warm water also provides heat transferred by convection to immersed body areas. A whirlpool or agitation device can be used to maintain a constant water temperature around the treated areas and provide gentle mechanical stimulation to the immersed body parts.
Fluidotherapy uses glass beads, pulverized corncobs, or other finely pulverized substances with low heat affinity that are heated by hot air to form a warm medium with liquid-like properties. The body part or extremity to be treated is immersed in a cabinet containing this dry and warm medium for treatment. Fluidotherapy is particularly useful for treating limbs affected by complex regional pain syndrome because it provides gentle tactile desensitization through stimulation of thermoreceptors and mechanoreceptors. Unlike hot packs and paraffin baths, there is no loss of heat over time. Stretching and exercise can also be performed during application of the heat.
When deep heating is required, ultrasound, short wave, and microwave diathermy can be used. These modalities deliver heat to deep tissues via conversion of physical energy to heat.
Ultrasound uses high-frequency sound waves to deliver energy to the target tissue. The sound waves produce thermal and nonthermal therapeutic effects. Ultrasound waves pass through, are absorbed, or are reflected, depending on the type of tissue encountered. Higher temperatures are generated when the ultrasound energy is absorbed. Energy is absorbed more effectively at muscle-bone interfaces, which results in higher tissue temperatures in these areas. Ultrasound is also more effective in heating tendons and ligaments than in heating muscle, which absorbs ultrasound relatively poorly.
Ultrasound is used clinically to treat subacute and chronic inflammatory soft tissue disorders such as tendinitis and bursitis. There is evidence that therapeutic ultrasound may improve acute shoulder pain in patients with calcific tendinitis. It can also be used for deep heating to facilitate stretching of contractures and shortened soft tissue structures. Low-intensity pulsed ultrasound has been shown to facilitate tissue repair and healing. Contraindications to the use of ultrasound are listed in Box 46.4 .
Contraindications to therapeutic heat
Laminectomy sites
Over a pregnant uterus
Over the heart or carotid sinus
Over an implanted pacemaker
Short wave diathermy uses electromagnetic radio waves to deliver heat down to 3 to 5 cm below the skin without overheating the skin and subcutaneous tissue. Indications for short wave diathermy are similar to those for ultrasound. Contraindications include the presence of metal, implanted pacemakers, spinal cord stimulators, surgical implants, and copper-containing intrauterine devices, because of the risk for excessive heating.
Microwave diathermy uses electromagnetic radio waves with frequencies of 915 and 2456 MHz. It is rarely used in current clinical practice. Protective eyewear must be worn during its application to minimize the risk for cataract formation. Because of its more rapid heating of tissues with high water content, it should not be used in patients with edema, blisters, or hyperhidrosis.
Short wave and microwave diathermy is not commonly used in clinical practice, partly because there are more contraindications ( Box 46.5 ) than with other heat agents and partly because of the availability and ease of use of other therapeutic heating options.
Contraindications to therapeutic heat
Near metallic implants
Over a pregnant uterus
Implanted pacemaker
Therapeutic Cold
Therapeutic cold is another time-tested modality used for pain relief and reduction of edema and muscle spasm. Other effects of cold include reduction of metabolic activity, muscle tone, and spasticity. Evidence that local cooling postoperatively reduces pain is mixed, with reports of a significant reduction in pain scores and opioid use after certain types of orthopedic surgery, but such results have not been demonstrated in other studies. There is no good-quality evidence that local cooling is effective in the treatment of low back pain. The rationale for using cold is similar to that for using therapeutic heat—as an adjunctive treatment to physical therapy and exercise.
Therapeutic cold can be delivered by means such as ice packs and slushes, iced whirlpools, ice rubs, chemical ice packs, and evaporative cooling sprays. The same general precautions for therapeutic heat should be used during therapeutic cold treatments to avoid thermal injury. Contraindications to therapeutic cold are listed in Box 46.6 .
