Physical Agents in Rehabilitation (4th Edition) PDF

Physical Agents in Rehabilitation From Research to Practice YOU’VE JUST PURCHASED MORE THAN A TEXTBOOK ACTIVATE THE COMPLETE LEARNING EXPERIENCE THAT COMES WITH YOUR BOOK BY REGISTERING AT http://evolve.elsevier.com/Cameron/Physical Students, make your study time more efficient and create your o...

Physical Agents in Rehabilitation From Research to Practice YOU’VE JUST PURCHASED MORE THAN A TEXTBOOK ACTIVATE THE COMPLETE LEARNING EXPERIENCE THAT COMES WITH YOUR BOOK BY REGISTERING AT http://evolve.elsevier.com/Cameron/Physical Students, make your study time more efficient and create your own custom study guides using the Evolve Student Resources for Cameron: Physical Agents in Rehabilitation, Fourth Edition. Highlights include: A  pplication technique videos: Many of the application techniques covered in the book are demonstrated for the student. E  lectrical Stimulation, Ultrasound, and Laser Light Handbook: This valuable resource gives students quick access to application parameters for several modalities. F  igure labeling activities: Select figures from the book are included here as an activity to help the student retain new information. G  lossaries: Glossaries from each chapter are available to help students become familiar with new terminology. R  eference lists linked to Medline abstracts: The reference lists from each chapter are linked, when available, to their citations on Medline. REGISTER TODAY! Physical Agents in Rehabilitation From Research to Practice Fourth Edition Michelle H. Cameron, MD, PT, OCS Oregon Health & Sciences University Portland, Oregon Occupational Therapy Consultant Julie Ann Nastasi, OTD, OTR/L, SCLV Faculty Specialist The University of Scranton Scranton, Pennsylvania  3251 Riverport Lane St. Louis, Missouri 63043 PHYSICAL AGENTS IN REHABILITATION, FROM RESEARCH TO PRACTICE, FOURTH EDITION ISBN: 978-1-4557-2848-0 Copyright © 2013, 2009, 2003 by Saunders, an imprint of Elsevier Inc. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications. It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data Cameron, Michelle H. Physical agents in rehabilitation : from research to practice / Michelle Cameron.—4th ed.    p. ; cm. Includes bibliographical references and index. ISBN 978-1-4557-2848-0 (pbk. : alk. paper) I. Title. [DNLM: 1. Physical Therapy Modalities. 2. Physical Therapy Modalities—instrumentation. 3. Rehabilitation—methods. WB 460] 615.8’2—dc23  2012023616 Content Manager: Jolynn Gower Content Developmental Specialist: Megan Fennell Publishing Services Manager: Catherine Jackson Senior Project Manager: Mary Pohlman Designer: Brian Salisbury Printed in China Last digit is the print number: 9 8 7 6 5 4 3 2 1 Dedication This book is dedicated to my friends. Thank you all for your support, encouragement, and patience through the rough patches, and for the reminders of joy past, present, and to come. This page intentionally left blank Biography Michelle H. Cameron, MD, PT, OCS, the primary author of Physical Agents in Rehabilitation: From Research to Practice, is a physical therapist and physician as well as an educator, researcher, and author. After ten years teaching rehabilitation providers about physical agents and working as a clinical physical therapist, Michelle furthered her own education through medical training. She now works as a neurologist with a focus on multiple sclerosis, while continuing to write and teach about the use of physical agents in rehabilitation. Michelle is the co-editor of the texts Physical Rehabilitation: Evidence-Based Examination, Evaluation, and Intervention and Physical Rehabilitation for the Physical Therapist Assistant. Michelle has written and edited many articles on electrical stimulation, ultrasound and phonophoresis, laser light therapy and wound management, and the section on ultrasound in Saunders’ Manual for Physical Therapy Practice. Michelle’s discussions of physical agents bring together current research and practice to provide the decision-making and hands-on tools to support optimal care within today’s health care environment. vii This page intentionally left blank Acknowledgments First and foremost, I want to thank the readers and purchasers of the previous editions of this book. Without you, this book would not exist. In particular, I would like to thank those readers who took the time to contact me with their comments, thoughts, and suggestions about what worked for them and what could be improved. I would also like to give special thanks to Ricky Chen, Research Assistant, for his help with updating this edition of the book, and particularly for his attention to detail, organization, reliability, and insight; Julie Nastasi, for her careful review of the text and valuable contributions to make this edition as relevant as possible for the occupational therapist reader; Megan Fennell, Content Development Specialist at Elsevier, for her consistent support throughout this project; Diane Allen, Linda Monroe, Sara Shapiro and Gail Widener, contributing authors to this and previous editions, who updated their respective chapters thoroughly and promptly; Eve Klein and Bill Rubine for their extensive update of Chapter 4 on pain; and Michelle Ocelnik for her comprehensive update of the electrical stimulation chapters. Thank you also to those who provided photos and pictures for illustrations, space and equipment for photos to be taken, and helped smooth the way through the myriad of details that add up to a book. Thank you all, Michelle H. Cameron ix This page intentionally left blank Contributors Diane D. Allen, PhD, PT William Rubine, MS, PT Associate Professor Outpatient Rehabilitation University of California San Francisco; Center For Health and Healing Associate Professor Oregon Health Sciences University San Francisco State University Portland, Oregon San Francisco, California Sara Shapiro, MPH, PT Eve L. Klein, MD Assistant Clinical Professor Pain Management Interventional Neurologist University of California, San Francisco; Legacy Health System Owner Vancouver, Washington Apex Wellness & Physical Therapy San Francisco, California Linda G. Monroe, MPT, OCS Physical Therapist Gail L. Widener, PhD, PT John Muir Health Associate Professor Walnut Creek, California Department of Physical Therapy Samuel Merritt College Michelle Ocelnik, MA, ATC, CSCS Oakland, California Director of Education and Research VQ OrthoCare Irvine, California Julie A. Pryde, MS, PA-C, PT, OCS, SCS, ATC, CSCS Senior Physician Assistant Muir Orthopaedic Specialists Walnut Creek, California xi This page intentionally left blank Preface By writing the first edition of this book I tried to meet resources include video clips of many patient proce- a need that I believed existed—the need for a book on dures from the book, figure labeling activities, glos- the use of physical agents in rehabilitation that cov- sary activities, and reference lists from each chapter ered the breadth and depth of this material in a read- linked to the relevant Medline source. Also, PDF ver- ily accessible, systematic, and easily understood man- sions of the glossaries, case studies, application tech- ner. I produced a text that leads the reader from the niques, and the Electrical Stimulation, Ultrasound, and basic scientific and physiological principles underly- Laser Light Handbook are available on Evolve for readers ing the application of physical agents to the research to create and print custom study or clinical quick- evaluating their clinical use and then to the practical reference guides. details of selecting and applying each specific physi- A number of changes have also been made to this cal agent to optimize patient outcomes. The enthusi- text to address changes in who uses physical agents asm with which the previous editions of this book in their practice, particularly the growing use of was received—including compliments from readers, physical agents by occupational therapists. Chapter 2, adoption by many educational programs, and pur- Physical Agents in Clinical Practice, specifically ad- chase by many clinicians, educators and students— dresses how different rehabilitation professionals use demonstrated that the need was there and was met. physical agents and the rules, regulations, and laws In all of the subsequent editions I have done my governing the practice and required education to best to keep the best from previous editions while apply physical agents. All the chapters on specific bringing the reader new and updated information, physical agents also have case studies appropriate for further clarifying the presented material, and improv- a range of professionals who use physical agents, spe- ing information accessibility. All editions of this book cifically including both upper and lower extremity provide easy-to-follow guidelines for safe application case examples. of all physical agents as well as the essential scientific In addition to these improvements, the entire rationale and evidence-base to select and apply inter- text has been updated with new references. Further- ventions with physical agents safely and effectively. more, a number of chapters have undergone larger As the quantity of research has increased, along with scale revisions. The chapter on pain has been thor- the quality, this text has become even more impor- oughly revised to reflect current understanding of tant for making clinical decisions. To keep up with people’s pain experiences and approaches to pain the pace of research, new developments in the field control. The information on electrical stimulation of rehabilitation, and technological advances in in- has also been developed and expanded. The infor- formation delivery, I have added a number of new mation is now presented in its own section with features to this edition. four separate chapters, the first introducing physical The most significant change to this edition of and physiological concepts common to all forms of Physical Agents in Rehabilitation is the development of electrical current application and the following the electronic resources. Although previous editions three chapters discussing the use of electrical cur- had some electronic resources, either on CD or on the rents to produce muscle contractions, control pain, web, with this edition the entire text is available as an and facilitate tissue healing. ebook, and has a companion Evolve site with additional resources for both the student and instructor (http:// Welcome to the fourth edition of Physical Agents in evolve.elsevier.com/Cameron/Physical). The student Rehabilitation! xiii This page intentionally left blank Contents Part I Introduction to Physical Agents 1 Glossary, 66 References, 67 1 The Physiology of Physical Agents 1 How to Use This Book, 1 5 Tone Abnormalities 72 What Are Physical Agents?, 2 Diane D. Allen and Gail L. Widener Categories of Physical Agents, 2 Muscle Tone, 72 Effects of Physical Agents, 3 Tone Abnormalities, 73 General Contraindications and Precautions for Physical Measuring Muscle Tone, 75 Agent Use, 9 Anatomical Bases of Muscle Tone and Activation, 78 Evaluation and Planning for the Use of Physical Agents, 10 Abnormal Muscle Tone and Its Consequences, 90 Documentation, 12 Clinical Case Studies, 98 Chapter Review, 12 Chapter Review, 101 Glossary, 12 Additional Resources, 101 References, 13 Glossary, 102 References, 103 2 Physical Agents in Clinical Practice 15 History of Physical Agents in Medicine and 6 Motion Restrictions 106 Rehabilitation, 15 Linda G. Monroe Approaches to Rehabilitation, 16 Types of Motion, 107 The Role of Physical Agents in Rehabilitation, 17 Patterns of Motion Restriction, 109 Practitioners Using Physical Agents, 17 Tissues That Can Restrict Motion, 109 Evidence-Based Practice, 18 Pathologies That Can Cause Motion Restriction, 110 Using Physical Agents Within Different Health Care Examination and Evaluation of Motion Restrictions, 112 Delivery Systems, 19 Contraindications and Precautions to Range of Motion Chapter Review, 20 Techniques, 115 Additional Resources, 20 Treatment Approaches for Motion Restrictions, 115 Glossary, 21 The Role of Physical Agents in the Treatment of Motion References, 21 Restrictions, 117 Clinical Case Studies, 118 Part II Pathology and Patient Problems 23 Chapter Review, 121 Additional Resources, 121 3 Inflammation and Tissue Repair 23 Glossary, 121 Julie A. Pryde References, 121 The Phases of Inflammation and Healing, 23 Chronic Inflammation, 36 Part III Thermal Agents 124 Factors Affecting the Healing Process, 38 Healing of Specific Musculoskeletal Tissues, 39 7 Introduction to Thermal Agents 124 Clinical Case Study, 41 Specific Heat, 124 Chapter Review, 42 Modes of Heat Transfer, 124 Additional Resources, 42 Chapter Review, 127 Glossary, 43 Additional Resources, 127 References, 44 Glossary, 127 References, 128 4 Pain 46 Michelle H. Cameron, William Rubine, 8 Superficial Cold and Heat 129 and Eve Klein Cryotherapy, 129 Mechanisms of Pain Reception and Transmission, 47 Effects of Cold, 129 Pain Modulation and Control, 50 Uses of Cryotherapy, 132 Types of Pain, 53 Contraindications and Precautions for Cryotherapy, 135 Assessing Pain, 55 Adverse Effects of Cryotherapy, 137 Pain Management, 58 Application Techniques, 137 Clinical Case Studies, 64 Documentation, 143 Chapter Review, 66 Clinical Case Studies, 144 Additional Resources, 66 Thermotherapy, 147 xv xvi CONTENTS Effects of Heat, 147 Documentation, 235 Uses of Superficial Heat, 149 Chapter Review, 235 Contraindications and Precautions for Additional Resources, 235 Thermotherapy, 150 Glossary, 236 Adverse Effects of Thermotherapy, 153 References, 239 Application Techniques, 154 12 Electrical Currents for Muscle Documentation, 163 Contraction 240 Clinical Case Studies, 163 Sara Shapiro and Michelle Ocelnik Choosing Between Cryotherapy and Thermotherapy, 168 Muscle Contraction in Innervated Muscle, 240 Chapter Review, 168 Clinical Applications of Electrically Stimulated Muscle Additional Resources, 168 Contraction, 242 Glossary, 168 Muscle Contraction in Denervated Muscle, 246 References, 169 Contraindications and Precautions for the Use of 9 Ultrasound 173 Electrical Currents for Muscle Contraction, 246 Introduction, 173 Parameters for Electrical Stimulation of Contraction by Effects of Ultrasound, 175 Innervated Muscles, 247 Clinical Applications of Ultrasound, 177 Documentation, 249 Contraindications and Precautions for the Use Clinical Case Studies, 250 of Ultrasound, 185 Chapter Review, 252 Adverse Effects of Ultrasound, 186 Additional Resources, 252 Application Technique, 187 Glossary, 253 Documentation, 189 References, 253 Clinical Case Studies, 190 13 Electrical Currents for Pain Control 257 Chapter Review, 194 Sara Shapiro and Michelle Ocelnik Additional Resources, 194 Pain Control, 257 Glossary, 194 Contraindications and Precautions for the Use of References, 198 Electrical Currents for Pain Control, 259 10 Diathermy 202 Parameters for Electrical Stimulation for Pain Physical Properties of Diathermy, 203 Control, 259 Types of Diathermy Applicators, 204 Documentation, 261 Effects of Diathermy, 208 Clinical Case Studies, 261 Clinical Indications for the Use of Diathermy, 208 Chapter Review, 264 Contraindications and Precautions for the Use Additional Resources, 264 of Diathermy, 210 Glossary, 264 Adverse Effects of Diathermy, 212 References, 265 Application Techniques, 212 14 Electrical Currents for Tissue Healing 267 Documentation, 215 Sara Shapiro and Michelle Ocelnik Selecting a Diathermy Device, 215 Electrical Currents for Tissue Healing, 267 Clinical Case Studies, 216 Contraindications and Precautions for the Use of Chapter Review, 219 Electrical Currents for Tissue Healing, 268 Additional Resources, 219 Wound Healing, 268 Glossary, 219 Edema Control, 271 References, 220 Iontophoresis, 272 Documentation, 276 Part IV Electrical Currents 223 Clinical Case Studies, 276 11 Introduction to Electrical Currents 223 Chapter Review, 279 Sara Shapiro and Michelle Ocelnik Additional Resources, 279 Introduction and History, 223 Glossary, 279 Electrical Current Parameters, 224 References, 280 Effects of Electrical Currents, 228 Contraindications and Precautions for the Use of Part V Electromagnetic Agents 283 Electrical Currents, 231 15 Lasers and Light 283 Adverse Effects of Electrical Currents, 233 Terminology, 283 Application Technique, 233 Introduction to Electromagnetic Radiation, 283  CONTENTS xvii Introduction to Lasers and Light, 286 Documentation, 352 Effects of Lasers and Light, 291 Clinical Case Studies, 353 Clinical Indications for the Use of Lasers and Light, 292 Chapter Review, 355 Contraindications and Precautions for the Use of Lasers Additional Resources, 356 And Light, 294 Glossary, 356 Application Technique for Lasers and Light, 296 References, 357 Documentation, 299 18 Traction 361 Clinical Case Studies, 299 Effects of Spinal Traction, 361 Chapter Review, 301 Clinical Indications for the Use of Spinal Traction, 364 Additional Resources, 302 Contraindications and Precautions for Use of Spinal Glossary, 302 Traction, 366 References, 303 Adverse Effects of Spinal Traction, 370 16 Ultraviolet Radiation 307 Application Techniques, 370 Physical Properties of Ultraviolet Radiation, 307 Documentation, 382 Effects of Ultraviolet Radiation, 308 Clinical Case Studies, 382 Clinical Indications for Ultraviolet Radiation, 310 Chapter Review, 387 Contraindications and Precautions for the Use of Additional Resources, 387 Ultraviolet Radiation, 312 Glossary, 387 Adverse Effects of Ultraviolet Radiation, 313 References, 387 Application Techniques, 314 19 Compression 390 Ultraviolet Therapy Application, 314 Effects of External Compression, 390 Documentation, 316 Clinical Indications for the Use of External Ultraviolet Lamps, 316 Compression, 391 Clinical Case Studies, 318 Contraindications and Precautions for the Use of External Chapter Review, 319 Compression, 398 Additional Resources, 319 Adverse Effects of External Compression, 401 Glossary, 319 Application Techniques, 401 References, 320 Documentation, 409 Clinical Case Studies, 410 Part VI Mechanical Agents 322 Chapter Review, 414 17 Hydrotherapy 322 Additional Resources, 415 Physical Properties of Water, 323 Glossary, 415 Physiological Effects of Hydrotherapy, 325 References, 415 Uses of Hydrotherapy, 329 Contraindications and Precautions for Appendix 419 Hydrotherapy, 337 Adverse Effects of Hydrotherapy, 341 Index 421 Application Techniques, 342 Safety Issues Regarding Hydrotherapy, Including Infection Control and Pool Safety, 350 This page intentionally left blank PART I Introduction to Physical Agents Chapter 1 The Physiology of Physical Agents OUTLINE will be able to integrate the ideal physical agent(s) and intervention parameters within a complete rehabilitation How to Use This Book program to promote optimal patient outcome. What Are Physical Agents? Categories of Physical Agents This book’s recommendations regarding the clinical use Thermal Agents of physical agents integrate concepts from a variety of Mechanical Agents sources. Specific recommendations are derived from the Electromagnetic Agents best available research-based evidence on the physiological Effects of Physical Agents effects and clinical outcomes of applying physical agents Inflammation and Healing to patients. The International Classification for Function- Pain ing, Disability, and Health (ICF) model of the World Health Collagen Extensibility and Motion Restrictions Organization (WHO) is used to consider and describe the Muscle Tone impact of physical agent interventions on patient out- General Contraindications and Precautions for Physical comes. This model was developed in 2001 as an approach Agent Use Pregnancy to describing functional abilities and differences and has Malignancy been adopted globally, particularly among rehabilitation Pacemaker or Other Implanted Electronic Device professionals.1 Additionally, the American Physical Therapy Impaired Sensation and Mentation Association’s Guide to Physical Therapist Practice, Evaluation and Planning for the Use of Physical Agents 2nd edition (The Guide) is widely used by physical thera- Choosing a Physical Agent pists to categorize patients according to preferred practice Attributes to Consider in the Selection of Physical Agents patterns.2 These patterns include typical findings and de- Using Physical Agents in Combination With Each Other or scriptive norms of types and ranges of interventions for With Other Interventions conditions in each pattern. Documentation After this introductory chapter, the book is divided into Chapter Review Glossary six parts: References Part I: Introduction to Physical Agents, introduces the physiological effects of physical agents and their clinical use by various professionals Part II: Pathology and Patient Problems, discusses typical HOW TO USE THIS BOOK musculoskeletal and neuromuscular problems ad- This book is intended primarily as a course text for those dressed by physical agents learning to use physical agents in rehabilitation. It Part III: Thermal Agents, covers thermal agents, includ- was written to meet the needs of students learning about ing superficial cold and heat, ultrasound, and the theory and practice of applying physical agents and to diathermy assist practicing rehabilitation professionals in reviewing Part IV: Electrical Currents, starts with a chapter that and updating their knowledge about the use of physical describes the physical properties of electrical cur- agents. This book describes the effects of physical agents, rents; this is followed by individual chapters on the gives guidelines on when and how physical agents can be use of electrical stimulation for muscle contraction, most effectively and safely applied, and describes the out- pain control, and tissue healing comes that can be expected from integrating physical Part V: Electromagnetic Agents, discusses lasers, light, and agents within a program of rehabilitation. The book cov- ultraviolet therapy ers the theory underlying the application of each agent Part VI: Mechanical Agents, covers hydrotherapy, traction, and the research concerning its effects, providing a ratio- and compression nale for the treatment recommendations. Information Video clips demonstrating various application tech- on the physiological processes influenced by physical niques are an important addition to the Evolve site for this agents is also provided. After reading this book, the reader edition. The Electrical Stimulation, Ultrasound, and Laser Light 1 2 PART I Introduction to Physical Agents Handbook is also available on Evolve, as well as links to affect one type of tissue more than another. For example, Medline for all cited journal references, additional re- a hot pack produces the greatest temperature increase in sources, review exercises using figures from the book, and superficial tissues with high thermal conductivity in the glossary activities to help reinforce new terminology. PDF area directly below it. In contrast, ultrasound produces versions of chapter glossaries, case studies, application heat in deeper tissues and produces the most heat in tis- techniques, and the handbook are available for use as a sues with high ultrasound absorption coefficients such as custom quick reference or study guide. tendon and bone. Diathermy, which involves the applica- tion of shortwave or microwave electromagnetic energy, WHAT ARE PHYSICAL AGENTS? heats deep tissues with high electrical conductivity. Physical agents consist of energy and materials applied to Thermotherapy is used to increase circulation, meta- patients to assist in rehabilitation. Physical agents include bolic rate, and soft tissue extensibility or to decrease pain. heat, cold, water, pressure, sound, electromagnetic radia- Cryotherapy is applied to decrease circulation, metabolic tion, and electrical currents. The term physical agent can be rate, or pain. A full discussion of the principles underlying used to describe the general type of energy, such as elec- the processes of heat transfer; the methods of heat transfer tromagnetic radiation or sound; a specific range within used in rehabilitation; and the effects, indications, and the general type, such as ultraviolet (UV) radiation contraindications for applying superficial heating and or ultrasound; and the actual means of applying the cooling agents is provided in Chapter 8. The principles energy, such as a UV lamp or an ultrasound transducer. and practice of applying deep-heating agents are discussed The terms physical modality, physical agent modality, in Chapter 9 in the section on thermal applications of electrophysical agent, and modality are frequently used in ultrasound and in Chapter 10 in the section on diathermy. place of the term physical agent and are used interchange- Ultrasound is a physical agent that has both thermal ably in this book. and nonthermal effects. Ultrasound is defined as sound with a frequency greater than 20,000 cycles/second. It can- CATEGORIES OF PHYSICAL AGENTS not be heard by humans because of its high frequency. Physical agents can be categorized as thermal, mechani- Ultrasound is a mechanical form of energy composed of cal, or electromagnetic (Table 1-1). Thermal agents in- alternating waves of compression and rarefaction. Thermal clude deep-heating agents, superficial heating agents, and effects, including increased deep and superficial tissue tem- superficial cooling agents. Mechanical agents include perature, are produced by continuous ultrasound waves of traction, compression, water, and sound. Electro- sufficient intensity, and nonthermal effects are produced magnetic agents include electromagnetic fields and by both continuous and pulsed ultrasound. Continu- electrical currents. Some physical agents fall into more ous ultrasound is used to heat deep tissues to increase than one category. Water and ultrasound, for example, circulation, metabolic rate, and soft tissue extensibility can have mechanical and thermal effects. and to decrease pain. Pulsed ultrasound is used to facilitate tissue healing or to promote transdermal drug penetration THERMAL AGENTS by nonthermal mechanisms. Further information on the Thermal agents transfer energy to a patient to produce an theory and practice of applying ultrasound can be found increase or decrease in tissue temperature. Examples of in Chapter 9. thermal agents include hot packs, ice packs, ultrasound, whirlpool, and diathermy. Cryotherapy is the thera- MECHANICAL AGENTS peutic application of cold, whereas thermotherapy is Mechanical agents apply force to increase or decrease pres- the therapeutic application of heat. Depending on the sure on the body. Examples of mechanical agents include thermal agent and the body part to which it is applied, water, traction, compression, and sound. Water can provide temperature changes may be superficial or deep and may resistance, hydrostatic pressure, and buoyancy for exercise or can apply pressure to clean open wounds. Traction de- creases the pressure between structures, and compression TABLE 1-1 Categories of Physical Agents increases the pressure on and between structures. Ultra- sound is discussed in the previous section. Category Types Clinical Examples The therapeutic use of water is called hydrotherapy. Thermal Deep-heating agents Ultrasound, diathermy Water can be applied with or without immersion. Immer- Superficial heating Hot pack sion in water increases pressure around the immersed agents area, provides buoyancy, and, if there is a difference in Cooling agents Ice pack temperature between the immersed area and the water is Mechanical Traction Mechanical traction present, transfers heat to or from that area. Movement of Compression Elastic bandage, water produces local pressure that can be used as resis- stockings tance for exercise when an area is immersed, and for Water Whirlpool cleansing or debriding of open wounds with or without Sound Ultrasound immersion. Further information on the theory and prac- Electromagnetic Electromagnetic Ultraviolet, laser tice of hydrotherapy is provided in Chapter 17. fields Electrical currents TENS Traction is most commonly used to alleviate pressure on structures such as nerves or joints that produce pain or TENS, Transcutaneous electrical nerve stimulation. other sensory changes, or that become inflamed when  The Physiology of Physical Agents CHAPTER 1 3 compressed. Traction can normalize sensation and pre- vent or reduce damage or inflammation of compressed EFFECTS OF PHYSICAL AGENTS structures. The pressure-relieving effects of traction may The application of physical agents primarily results in be temporary or permanent, depending on the nature of modification of tissue inflammation and healing, relief of the underlying pathology and the force, duration, and pain, alteration of collagen extensibility, or modification means of traction application used. Further information of muscle tone. A brief review of these processes follows; on the theory and practice of applying traction is pro- more complete discussions of these processes are provided vided in Chapter 18. in Chapters 3 through 6. A brief discussion of physical Compression is used to counteract fluid pressure and to agents that modify each of these conditions is included control or reverse edema. The force, duration, and means here, and the chapters in Parts III through VI of this book of applying compression can be varied to control the mag- cover each of the physical agents in detail. nitude of the effect and to accommodate different patient needs. Further information on the theory and practice of INFLAMMATION AND HEALING applying compression is provided in Chapter 19. When tissue is damaged, it usually responds predictably. Inflammation is the first phase of recovery, followed by ELECTROMAGNETIC AGENTS the proliferation and maturation phases. Modifying this Electromagnetic agents apply energy in the form of elec- healing process can accelerate rehabilitation and reduce tromagnetic radiation or an electrical current. Examples adverse effects, such as prolonged inflammation, pain, of electromagnetic agents include UV radiation, infra- and disuse. This in turn leads to improved patient func- red (IR) radiation, laser, diathermy, and electrical tion and more rapid achievement of therapeutic goals. current. Variation of the frequency and intensity of elec- Thermal agents modify inflammation and healing by tromagnetic radiation changes its effects and depth of changing the rates of circulation and chemical reactions. penetration. For example, UV radiation, which has a fre- Mechanical agents control motion and alter fluid flow, quency of 7.5 3 1014 to 1015 cycles/second (Hertz, Hz), and electromagnetic agents alter cell function, particularly produces erythema and tanning of the skin but does not membrane permeability and transport. Many physical produce heat, whereas IR radiation, which has a fre- agents affect inflammation and healing and, when appro- quency of 1011 to 1014 Hz, produces heat only in super­ priately applied, can accelerate progress, limit adverse ficial tissues. Lasers output monochromatic, coherent, consequences of the healing process, and optimize the directional electromagnetic radiation that is generally in final patient outcome (Table 1-2). However, when poorly the frequency range of visible light or IR radiation. Con- selected or misapplied, physical agents may impair or tinuous shortwave diathermy, which has a frequency of potentially prevent complete healing. 105 to 106 Hz, produces heat in both superficial and deep During the inflammatory phase of healing, which tissues. When shortwave diathermy is pulsed (pulsed generally lasts for 1 to 6 days, cells that remove debris shortwave diathermy [PSWD]) to provide a low aver- and limit bleeding enter the traumatized area. The inflam- age intensity of energy, it does not produce heat; how- matory phase is characterized by heat, swelling, pain, red- ever, the electromagnetic energy is thought to modify cell ness, and loss of function. The more quickly this phase membrane permeability and cell function by nonthermal is completed and resolved, the more quickly healing can mechanisms and may thus control pain and edema. proceed, and the lower the probability of joint destruc- These agents are thought to facilitate healing via bios- tion, excessive pain, swelling, weakness, immobilization, timulative effects on cells. Further information on the and loss of function. Physical agents generally assist theory and practice of applying electromagnetic radiation during the inflammation phase by reducing circulation, and on lasers and other forms of light is provided in reducing pain, reducing the enzyme activity rate, controlling Chapter 15. UV radiation and diathermy are discussed in motion, and promoting progression to the proliferation Chapters 16 and 10, respectively. phase of healing. Electrical stimulation (ES) is the use of electrical During the proliferation phase, which generally starts current to induce muscle contraction (motor level ES) and within the first 3 days after injury and lasts for approxi- changes in sensation (sensory level ES), reduce edema, or mately 20 days, collagen is deposited in the damaged area accelerate tissue healing. The effects and clinical applica- to replace tissue that was destroyed by trauma. In addi- tions of electrical currents vary according to the wave- tion, if necessary, myofibroblasts contract to accelerate form, intensity, duration, and direction of the current closure, and epithelial cells migrate to resurface the flow and according to the type of tissue to which the cur- wound. Physical agents generally assist during the prolif- rent is applied. Electrical currents of sufficient intensity eration phase of healing by increasing circulation and the and duration can depolarize nerves, causing sensory or enzyme activity rate and by promoting collagen deposi- motor responses that may be used to control pain or in- tion and progression to the remodeling phase of healing. crease muscle strength and control. Electrical currents During the maturation phase, which usually starts with an appropriate direction of flow can attract or repel approximately 9 days after the initial injury and can last charged particles and alter cell membrane permeability to for up to 2 years, both deposition and resorption of colla- control the formation of edema, promote tissue healing, gen occur. The new tissue remodels itself to resemble the and facilitate transdermal drug penetration. Further infor- original tissue as closely as possible to best serve its original mation on the theory and practice of electrical current function. During this phase, the healing tissue changes in application is provided in Part IV. both shape and structure to allow for optimal functional 4 PART I Introduction to Physical Agents TABLE 1-2 Physical Agents for Promoting Tissue Healing Stage of Tissue Healing Goals of Treatment Effective Agents Contraindicated Agents Initial injury Prevent further injury or bleeding Static compression, cryotherapy Exercise Intermittent traction Motor level ES Thermotherapy Clean open wound Hydrotherapy (immersion or nonimmersion) Chronic inflammation Prevent/decrease joint stiffness Thermotherapy Cryotherapy Motor ES Whirlpool Fluidotherapy Control pain Thermotherapy Cryotherapy ES Laser Increase circulation Thermotherapy ES Compression Hydrotherapy (immersion or exercise) Progress to proliferation stage Pulsed ultrasound ES PSWD Remodeling Regain or maintain strength Motor ES Immobilization Water exercise Regain or maintain flexibility Thermotherapy Immobilization Control scar tissue formation Brief ice massage Compression ES, Electrical stimulation; PSWD, pulsed shortwave diathermy. recovery. The shape conforms more closely to the original vascular lesions through vasodilation.5-7 Hydrotherapy, tissue, often decreasing in size from the proliferation involving immersion or nonimmersion techniques, can phase, and the structure becomes more organized. Thus be used to cleanse the injured area if the skin has been greater strength is achieved with no change in tissue mass. broken and the wound has become contaminated; how- Physical agents generally assist during the remodeling ever, because thermotherapy is contraindicated, only neu- phase of healing by altering the balance of collagen deposi- tral warmth or cooler water should be used.8 tion and resorption and improving the alignment of new collagen fibers. Acute Inflammation. ​During the acute inflammatory stage of healing, the goals of intervention are to control Physical Agents for Tissue Healing pain, edema, bleeding, and the release and activity of in- The stage of tissue healing determines the goals of inter- flammatory mediators and to facilitate progression to the vention and the physical agents to be used. The following proliferation stage. A number of physical agents, includ- discussion is summarized in Table 1-2. ing cryotherapy, hydrotherapy, ES, and PSWD, can be used to control pain; however, the use of thermotherapy, Initial Injury. ​Immediately after injury or trauma, the intermittent traction, and motor level ES is not appropri- goals of intervention are to prevent further injury or ate.9-13 Thermotherapy is not recommended because it bleeding and to clean away wound contaminants if the causes vasodilation, which may aggravate edema, and it skin has been broken. Immobilization and support of the increases the metabolic rate, which may increase the in- injured area with a static compression device, such as an flammatory response. Intermittent traction and motor elastic wrap, a cast, or a brace, or reduction of stress on the level ES should be used with caution because the move- area with the use of assistive devices, such as crutches, can ment produced by these physical agents may cause further limit further injury and bleeding. Motion of the injured tissue irritation, thereby aggravating the inflammatory area, whether active, electrically stimulated, or passive, is response. A number of physical agents, including cryo- contraindicated at this stage because this can lead to fur- therapy, compression, sensory level ES, PSWD, and con- ther tissue damage and bleeding. Cryotherapy will con- trast bath, may be used to control or reduce edema.14-17 tribute to the control of bleeding by limiting blood flow Cryotherapy and compression can also help to control to the injured area through vasoconstriction and in- bleeding; furthermore, cryotherapy inhibits the activity creased blood viscosity.3,4 Thermotherapy is contraindi- and release of inflammatory mediators. If healing is cated at this early stage because it can increase bleeding at delayed because of inhibition of inflammation, which the site of injury by increasing blood flow or reopening may occur in the patient who is on high-dose catabolic  The Physiology of Physical Agents CHAPTER 1 5 corticosteroids, cryotherapy should not be used because provided by the water may also assist motion should it may further impair the process of inflammation, thus the muscles be very weak, and water-based exercise and potentially delaying tissue healing. Evidence indicates thermotherapy may promote circulation and help to that pulsed ultrasound, laser light, and PSWD may pro- maintain or increase flexibility.35,36 mote progression from the inflammation stage to the proliferation stage of healing.18-20 Maturation. ​During the final stage of tissue healing— maturation—the goals of intervention are to regain or Chronic Inflammation. ​If the inflammatory response maintain strength and flexibility and to control scar persists and becomes chronic, the goals and thus the selec- tissue formation. At this point in the healing process, tion of interventions will change. During this stage of injured tissues are approaching their final form. There- healing, the goals of treatment are to prevent or decrease fore, treatment should focus on reversing any adverse joint stiffness, control pain, increase circulation, and pro- effects of earlier stages of healing, such as weakening mote progression to the proliferation stage. The most of muscles or loss of flexibility. Strengthening and effective interventions for reducing joint stiffness are ther- stretching exercises most effectively address these prob- motherapy and motion.21,22 Superficial structures, such as lems. Strengthening may be more effective with the the skin and subcutaneous fascia, may be heated by super- addition of motor level ES or water exercise, whereas ficial heating agents, for example, hot packs or paraffin, stretching may be more effective with prior application which is a waxy substance that can be warmed and used of thermotherapy or brief ice massage.21,37 If the injury to coat the extremities for thermotherapy. However, to is the type particularly prone to excessive scar forma- heat deeper structures, such as the shoulder or hip joint tion, such as a burn, control of scar formation with capsules, deep-heating agents, such as ultrasound or dia- compression garments should be continued throughout thermy, must be used.23-25 Motion may be produced by the remodeling stage. active exercise or ES, and motion can be combined with heat by having the patient exercise in warm water, or PAIN fluidotherapy. Thermotherapy and ES can be used to Pain is an unpleasant sensory and emotional experience relieve pain during the chronic inflammatory stage; how- associated with actual or threatened tissue damage. Pain ever, cryotherapy generally is not recommended during usually protects individuals by preventing them from per- this stage because it can increase the joint stiffness fre- forming activities that would cause tissue damage; how- quently associated with chronic inflammation. Selection ever, it may also interfere with normal activities and cause between thermotherapy and ES generally depends on functional limitation and disability. For example, pain can the need for additional benefits of each modality and on interfere with sleep, work, or exercise. Relieving pain can the other selection factors discussed later. Circulation may allow patients to participate more fully in normal activi- be increased through the use of thermotherapy, ES, com- ties of daily living and may accelerate the initiation of pression, water immersion, or exercise, and possibly by an active rehabilitation program, thereby limiting the the use of contrast baths.5,26-30 A final goal of treatment at adverse consequences of disuse and allowing more rapid the chronic inflammatory phase of tissue healing is to progress toward the patient’s functional goals. promote progression to the proliferation phase. Some Pain may be the result of an underlying pathology, studies indicate that pulsed ultrasound, electrical currents, such as joint inflammation or pressure on a nerve that is and electromagnetic fields may promote this transition. in the process of resolution, or a malignancy that is not expected to fully resolve. In either circumstance, relieving Proliferation. ​Once the injured tissue moves beyond pain may improve the patient’s levels of activity and par- the inflammation stage to the proliferation stage of heal- ticipation. Pain-relieving interventions, including physi- ing, the primary goals of intervention become controlling cal agents, may be used as long as pain persists and should scar tissue formation, ensuring adequate circulation, main- be discontinued when pain resolves. taining strength and flexibility, and promoting progression Physical agents can control pain by modifying pain to the remodeling stage. Static compression garments transmission or perception or by changing the underlying can control superficial scar tissue formation, promoting process causing the sensation. Physical agents may act by enhanced cosmesis and reducing the severity and inci- modulating transmission at the spinal cord level, chang- dence of contractures.31-33 Adequate circulation is required ing the rate of nerve conduction, or altering the central or to provide oxygen and nutrients to newly forming tissue. peripheral release of neurotransmitters. Physical agents Circulation may be enhanced by the use of thermotherapy, can change the processes that cause pain by modifying electrotherapy, compression, water immersion, or exercise, tissue inflammation and healing, altering collagen exten- and possibly by the use of contrast baths. Although active sibility, or modifying muscle tone. The processes of pain exercise can increase or maintain strength and flexibility perception and pain control are explained in greater detail during the proliferation stage of healing, the addition of in Chapter 4. motor level ES or water exercise may accelerate recovery and provide additional benefit. The water environment Physical Agents for Pain Modulation reduces loading and thus the potential for trauma to The choice of a physical agent for treating pain depends weight-bearing structures, and thereby may decrease the on the type and cause of the pain. Physical agents used for risk of regression to the inflammatory stage.34 Support pain are summarized in Table 1-3. 6 PART I Introduction to Physical Agents TABLE 1-3 Physical Agents for the Treatment of Pain Type of Pain Goals of Treatment Effective Agents Contraindicated Acute Control pain Sensory ES, cryotherapy Control inflammation Cryotherapy Thermotherapy Prevent aggravation of pain Immobilization Local exercise, motor ES Low-load static traction Referred Control pain ES, cryotherapy, thermotherapy Spinal radicular Decrease nerve root inflammation Traction Decrease nerve root compression Pain caused by malignancy Control pain ES, cryotherapy, superficial thermotherapy ES, Electrical stimulation. Acute Pain. ​For acute pain, the goals of intervention are function, should be discouraged in this patient popula- to control the pain and any associated inflammation and tion, and because passive physical agent treatments pro- to prevent aggravation of the pain or its cause. Many vided by a clinician can encourage dependence on the physical agents, including sensory level ES, cryotherapy, clinician rather than improving the patient’s own coping and laser light, can relieve or reduce the severity of acute skills, such interventions generally are not recommended pain.9,10 Thermotherapy may reduce the severity of acute for the treatment of chronic pain. The judicious use of pain; however, because acute pain is frequently associated pain-controlling physical agents by patients themselves with acute inflammation, which is aggravated by thermo- may be indicated when this helps to improve the patient’s therapy, thermotherapy generally is not recommended for ability to cope with pain on a long-term basis; however, it the treatment of acute pain.38 Cryotherapy is thought to is important that such interventions do not excessively control acute pain by modulating transmission at the spi- disrupt the patient’s functional activities. For example, nal cord, by slowing or blocking nerve conduction, and by transcutaneous electrical nerve stimulation (TENS) ap- controlling inflammation and its associated signs and plied by a patient to relieve or reduce chronic back pain symptoms.9 Sensory level ES also relieves acute pain by may promote function by allowing him to participate in modulating transmission at the spinal cord or by stimulat- work-related activities; however, a hot pack applied by the ing the release of endorphins. Briefly limiting motion of a patient for 20 minutes every few hours would interfere painful area with the aid of a static compression device, an with his ability to perform normal functional activities assistive device, or bed rest can prevent aggravation of the and therefore would not be recommended. symptom or cause of acute pain. Very low-load, prolonged static traction may be used for several hours or even a few Referred Pain. ​If the patient’s pain is referred to a mus- days to temporarily immobilize a symptomatic spinal culoskeletal area from an internal organ or from another area, thereby relieving the spinal pain and inflammation musculoskeletal area, physical agents may be used to con- that would be aggravated by lumbar spine motion.39,40 trol it; however, the source of the pain should also be Excessive movement or muscle contraction in the area of treated if possible. Pain-relieving physical agents, such as acute pain is generally contraindicated; thus exercise or thermotherapy, cryotherapy, or ES, may control referred motor level ES of this area should be avoided or restricted pain and may be particularly beneficial if complete resolu- to a level that does not exacerbate pain. As acute pain tion of the problem is prolonged or cannot be achieved. starts to resolve, controlled reactivation of the patient For example, although surgery may be needed to fully re- may accelerate pain resolution. The water environment lieve pain caused by endometriosis, if the disease does not may be used to facilitate such activity. place the patient at risk, interventions such as physical or pharmacological agents may be used for pain control. Chronic Pain. ​Pain that does not resolve within the Radicular pain in the extremities caused by spinal nerve normal recovery time expected for an injury or disease is root dysfunction may be effectively treated by the applica- known as chronic pain.41 The goals of intervention for tion of spinal traction or by the use of physical agents that chronic pain shift from resolution of the underlying cause sensory stimulation of the involved dermatome, such pathology and control of symptoms to promotion of as thermotherapy, cryotherapy, or ES.42,43 Spinal traction is function, enhancement of strength, and improvement of effective in such circumstances because it can reduce nerve coping skills. Although psychological interventions are root compression, addressing the source of the pain, the mainstay of improving coping skills in patients with whereas sensory stimulation may modulate the transmis- chronic pain, exercise should be used to regain strength sion of pain at the spinal cord level.44 and function. The water environment may be used to promote the development of functional abilities and the Pain Caused by Malignancy. ​Treatment of pain caused capacity of certain patients with chronic pain, and both by malignancy may differ from treatment of pain from motor level ES and water exercise may be used to increase other causes because particular care must be taken to avoid muscle strength in weak or deconditioned patients. Bed using agents that can promote the growth or metastasis of rest, which can result in weakness and can further reduce malignant tissue. Because the growth of some malignancies  The Physiology of Physical Agents CHAPTER 1 7 can be accelerated by increasing local circulation, agents such as ultrasound and diathermy, which are known to increase deep tissue temperature and circulation, generally should not be used in an area of malignancy.45,46 However, in patients with end-stage malignancies, pain-relieving Collagen extensibility interventions that can improve the patient’s quality of life but may adversely affect disease progression may be used with the patient’s informed consent. Complex Regional Pain Syndrome. ​Complex regional pain syndrome (CRPS) is pain believed to involve overacti- vation of the sympathetic nervous system. Physical agents can be used to control the pain of CRPS with sympathetic nervous system involvement. In general, low-level sensory Temperature stimulation of the involved area, as can be provided by neutral warmth, mild cold, water immersion, or gentle agi- tation of fluidotherapy, may be effective, whereas more FIG 1-1 ​Changes in collagen extensibility in response to changes in aggressive stimulation, as can be provided by very hot wa- temperature. ter, ice, or aggressive agitation of water or fluidotherapy, probably will not be tolerated and may aggravate this type of pain. the development and treatment of motion restrictions are discussed in detail in Chapter 6. COLLAGEN EXTENSIBILITY AND MOTION RESTRICTIONS Physical Agents for the Treatment of Motion Collagen is the main supportive protein of skin, tendon, Restrictions bone cartilage, and connective tissue.47 Tissues that con- Physical agents can be effective adjuncts to the treatment tain collagen can become shortened as a result of being of motion restrictions caused by muscle weakness, pain, immobilized in a shortened position or being moved soft tissue shortening, or a bony block; however, appropri- through a limited range of motion (ROM). Immobiliza- ate interventions for these different sources of motion tion may result from disuse caused by debilitation or restriction vary (Table 1-4). When active motion is re- neural injury or may be caused by the application of an stricted by muscle weakness, treatment should be aimed at external device such as a cast, brace, or external fixator. increasing muscle strength. This can be achieved by re- Movement may be limited by internal derangement, pain, peated overload muscle contraction through active exercise weakness, poor posture, or an external device. Shortening and may be enhanced by exercise in water or motor level of muscles, tendons, or joint capsules may cause restricted ES. Water can provide support to allow weaker muscles to joint ROM. move joints through greater range and can provide resis- To return soft tissue to its normal functional length and tance against which stronger muscles can work. Motor level thereby allow full motion without damaging other struc- ES can provide preferential training of larger muscle fibers, tures, the collagen must be stretched. Collagen can be isolation of specific muscle contraction, and precise control stretched most effectively and safely when it is most ex- of the timing and number of muscle contractions. When tensible. Because the extensibility of collagen increases in ROM is limited by muscle weakness alone, rest and immo- response to increased temperature, thermal agents are bilization of the area are contraindicated because restricting frequently applied before soft tissue stretching to optimize active use of weakened muscles will further reduce their the stretching process (Fig. 1-1).48-51 Processes underlying strength, thus exacerbating existing motion restriction. TABLE 1-4 Physical Agents for the Treatment of Motion Restrictions Source of Motion Restriction Goals of Treatment Effective Agents Contraindicated Muscle weakness Increase muscle strength Water exercise, motor ES Immobilization Pain At rest and with motion Control pain ES, cryotherapy, thermotherapy, PSWD, spinal traction Exercise With motion only Control pain ES, cryotherapy, thermotherapy, PSWD Exercise into pain Promote tissue healing Soft tissue shortening Increase tissue extensibility Thermotherapy Prolonged cryotherapy Increase tissue length Thermotherapy or brief ice massage and stretch Bony block Remove block None Stretching blocked joint Compensate Exercise Thermotherapy or brief ice massage and stretch ES, Electrical stimulation; PSWD, pulsed shortwave diathermy. 8 PART I Introduction to Physical Agents When motion is restricted by pain, treatment selection joint that is blocked by a bony obstruction is not recom- will depend on whether the pain occurs at rest and with mended because this force will not increase ROM at all motion, or if it occurs in response to active or passive that joint and may cause inflammation by traumatizing motion only. When motion is restricted by pain that is intraarticular structures. present at rest and with all motion, the first goal of treat- ment is to reduce the severity of the pain. This can be MUSCLE TONE achieved, as was previously described, with the use of ES, Muscle tone is the underlying tension that serves as back- cryotherapy, thermotherapy, or PSWD. If pain and motion ground for contraction of a muscle.56 Muscle tone is restriction are related to compressive spinal dysfunction, affected by neural and biomechanical factors and can vary spinal traction may be used to alleviate pain and promote in response to pathology, expected demand, pain, and increased motion. When pain restricts motion with active position.57 Abnormal muscle tone is usually the direct motion only, this indicates an injury of contractile tissue, result of nerve pathology or may be a secondary sequela such as muscle or tendon, without complete rupture.52 of pain that results from injury to other tissues.58 When both active motion and passive motion are re- Central nervous system injury, as may occur with head stricted by pain, noncontractile tissue, such as ligament or trauma or stroke, can result in increased or decreased meniscus, is involved. Physical agents may help restore muscle tone in the affected area, whereas peripheral mo- motion after an injury to contractile or noncontractile tor nerve injury, as may occur with nerve compression, tissue by promoting tissue healing or by controlling pain, traction, or sectioning, can decrease muscle tone in the which has already been described. affected area. For example, a patient who has had a stroke When active motion and passive motion are restricted may have increased tone in the flexor muscles of the by soft tissue shortening or by a bony block, the restric- upper extremity and the extensor muscles of the lower tion generally is not accompanied by pain. Soft tissue extremity on the same side, whereas a patient who has shortening may be reversed by stretching, and thermal had a compression injury to the radial nerve as it passes agents may be used before or in conjunction with stretch- through the radial groove in the arm may have decreased ing to increase soft tissue extensibility, thus promoting a tone in the wrist and finger extensors. safer, more effective stretch.35,36,53 The ideal thermal agent Pain may cause an increase or decrease in muscle depends on the depth, size, and contouring of the tissue tone. Muscle tone may be increased in the muscles sur- to be treated. Deep-heating agents, such as ultrasound or rounding a painful injured area to splint the area and diathermy, should be used when motion is restricted by limit motion, or tone in a painful area may be decreased shortening of deep tissues, such as the shoulder joint cap- as a result of inhibition. Although protective splinting sule, whereas superficial heating agents, such as hot packs, may prevent further injury from excessive activity, if paraffin, warm whirlpools, or IR lamps, should be used prolonged, it can impair circulation, retarding or pre- when motion is restricted by shortening of superficial tis- venting healing. Decreased muscle tone as a result of sues such as the skin or subcutaneous fascia. Ultrasound pain—as occurs, for example, with reflexive hypotonic- should be used for treating small areas of deep tissue, ity (decreased muscle tone) of the knee extensors that whereas diathermy is more appropriate for larger areas. causes buckling of the knee when knee extension is Hot packs can be used to treat large or small areas of su- painful—can limit activity. perficial tissue with little or moderate contouring. Paraffin Physical agents can alter muscle tone directly by alter- or a whirlpool is more appropriate for treating small areas ing nerve conduction, nerve sensitivity, or biomechanical with greater contouring. IR lamps can be used to heat properties of muscle, or indirectly by reducing pain or the large or small areas, but they provide consistent heating underlying cause of pain. Normalizing muscle tone gener- only to relatively flat surfaces. Because increasing tissue ally reduces functional limitations and disability, allowing extensibility alone will not decrease soft tissue shortening, the individual to improve performance of functional and thermal agents must be used in conjunction with stretch- therapeutic activities. Attempting to normalize muscle ing techniques to increase soft tissue length and reverse tone may promote better outcomes from passive treat- motion restrictions caused by soft tissue shortening. Brief ment techniques such as passive mobilization or position- forms of cryotherapy, such as brief ice massage or vapo- ing. Processes underlying changes in muscle tone are coolant sprays, may be used before stretching to facilitate discussed fully in Chapter 5. greater increases in muscle length by reducing the discom- fort of stretching; however, prolonged cryotherapy should Physical Agents for Tone Abnormalities not be used before stretching because cooling soft tissue Physical agents can temporarily modify muscle hyperto- decreases its extensibility.54,55 nicity, hypotonicity, or fluctuating tone (Table 1-5). Hy- When a bony block restricts motion, the goal of inter- pertonicity may be reduced directly by the application of vention is to remove the block or to compensate for loss neutral warmth or prolonged cryotherapy to hypertonic of motion. Physical agents cannot remove a bony block, muscles, or it may be reduced indirectly by stimulation of but they may help with compensation for loss of motion antagonist muscle contraction motor-level ES or quick by facilitating increased motion at other joints. Motion icing. Stimulation of antagonist muscles indirectly re- may be increased at other joints by the judicious use duces hypertonicity because stimulated activity in these of thermotherapy or brief cryotherapy with stretching. muscles causes reflex relaxation and tone reduction in Such treatment should be applied with caution to avoid opposing muscles.59 In the past, stimulation of hyper- injury, hypermobility, and other types of dysfunction in tonic muscles with motor level ES or quick icing generally previously normal joints. Applying a stretching force to a was not recommended because of concern that this  The Physiology of Physical Agents CHAPTER 1 9 TABLE 1-5 Physical Agents for the Treatment of Tone Abnormalities Tone Abnormality Goals of Treatment Effective Agents Contraindicated Hypertonicity Decrease tone Neutral warmth or prolonged cryotherapy to hypertonic muscles Quick ice of agonist Motor ES or quick ice of antagonists Hypotonicity Increase tone Quick ice or motor ES of agonists Thermotherapy Fluctuating tone Normalize tone Functional ES ES, Electrical stimulation. would further increase muscle tone; however, reports PREGNANCY indicate that ES of hypertonic muscles improves patient Pregnancy is generally a contraindication or precaution function by increasing strength and voluntary control of for the application of a physical agent if the energy pro- these muscles.60,61 duced by that agent or its physiological effects may reach In patients with muscle hypotonicity, in which the the fetus. These restrictions apply because the influences goal of intervention is to increase tone, quick icing or mo- of these types of energy on fetal development usually are tor level ES of hypotonic muscles may be beneficial. In not known, and because fetal development is adversely contrast, application of heat to these muscles should gen- affected by many influences, some of which are subtle. erally be avoided because this may further reduce muscle tone. In patients with fluctuating tone, for whom the goal MALIGNANCY of treatment is to normalize tone, functional ES may be Malignancy is a contraindication or precaution for the applied to cause a muscle or muscles to contract at the application of physical agents if the energy produced by appropriate time during functional activities. For exam- the agent or its physiological effects may reach malignant ple, if a patient cannot maintain a functional grasp be- tissue or alter the circulation to such tissue. Some physical cause he cannot contract the wrist extensors while con- agents are known to accelerate the growth, or metastasis, tracting the finger flexors, contraction of the wrist of malignant tissue. These effects are thought to result extensors can be produced by ES at the appropriate time from increased circulation or altered cellular function. during active grasping. Care must be taken when consideration is given to treat- ing any area of the body that currently has or previously GENERAL CONTRAINDICATIONS had cancer cells because malignant tissue can metastasize AND PRECAUTIONS FOR PHYSICAL and therefore may be present in areas where it has not yet AGENT USE been detected. Restrictions on the use of particular treatment interven- tions are categorized as contraindications or precautions. PACEMAKER OR OTHER IMPLANTED Contraindications are conditions under which a particular ELECTRONIC DEVICE treatment should not be applied, and precautions are The use of a physical agent is generally contraindicated conditions under which a particular form of treatment when the energy of the agent can reach a pacemaker or should be applied with special care or limitations. The any other implanted electronic device (e.g., deep brain terms absolute contraindications and relative contraindi- stimulator, spinal cord stimulator) because the energy cations can be used in place of contraindications and produced by some of these agents may alter the function- precautions, respectively. ing of the device, thus adversely affecting the patient. Although contraindications and precautions for the ap- plication of specific physical agents vary, several condi- IMPAIRED SENSATION AND MENTATION tions are contraindications or precautions for the use of Impaired sensation and mentation are contraindications most physical agents. Therefore, caution should be used or precautions for the use of many physical agents because when application of a physical agent to a patient with any the end limit for application of these agents is the of these conditions is considered. In patients with such patient’s report of how the intervention feels. For exam- conditions, the nature of the restriction, the nature and ple, for most thermal agents, the patient’s report of the distribution of the physiological effects of the physical sensation of heat as comfortable or painful is used as a agent, and the distribution of energy produced by the guide to limit the intensity of treatment. If the patient physical agent must be considered. cannot feel heat or pain because of impaired sensation or cannot report this sensation accurately and consistently because of impaired mentation or other factors affecting CONTRAINDICATIONS his or her ability to communicate, application of the treat- for Application of a Physical Agent ment would not be safe and therefore is contraindicated. Although these conditions indicate the need for cau- Pregnancy tion with the use of most physical agents, the specific Malignancy contraindications and precautions for the agent being Pacemaker or other implanted electronic device considered and the patient situation must be evaluated Impaired sensation before an intervention may be used or should be rejected. Impaired mentation For example, although application of ultrasound to a 10 PART I Introduction to Physical Agents pregnant patient is contraindicated in any area where the presented here in narrative form and are summarized in ultrasound may reach the fetus, this physical agent may Tables 1-2 to 1-5. If the patient presents with more than one be applied to the distal extremities of a pregnant patient problem and has numerous goals for treatment, a limited because ultrasound penetration is limited to the area close number of goals may need to be addressed at any one time. to the applicator. In contrast, it is recommended that dia- It is generally recommended that the primary problems thermy not be applied to any part of a pregnant patient and those most likely to respond to available interventions because the electromagnetic radiation produced by this should be addressed first; however, the ideal intervention type of agent reaches areas distant from the applicator. will facilitate progress in a number of areas (Fig. 1-2). For Specific contraindications and precautions, including example, if a patient has knee pain caused by acute joint questions to ask the patient and features to assess before inflammation, treatment should first be directed at resolv- the application of each physical agent, are provided in ing the inflammation; however, the ideal intervention Part II of this book. would also help to relieve pain. When the primary under- lying problem, such as arthritis, cannot benefit directly from intervention with a physical agent, treatment with EVALUATION AND PLANNING FOR physical agents may still be used to help alleviate sequelae THE USE OF PHYSICAL AGENTS of these problems, such as pain or swelling. Physical agents have direct effects primarily at the level of impairment. These effects can promote improved activity Attributes to Consider in the Selection and participation. For example, for a patient with pain of Physical Agents that impairs motion, electrical currents can be used to Given the variety of available physical agents and the stimulate sensory nerves to control pain and allow the unique characteristics of each patient, it is helpful to take patient to increase motion and thus increase activity, such a systematic approach to selection of physical agents, as lifting objects, and participation, such as returning to so the ideal physical agent is applied in each situation work. Physical agents can also increase the effectiveness of (Fig. 1-3). The first consideration should be the goals of other interventions. They are used in conjunction with or the intervention and the physiological effects required to in preparation for therapeutic exercise, functional train- reach these goals. If the patient has inflammation, pain, ing, and manual mobilization. For example, a hot pack motion restrictions, or problems with muscle tone, use may be applied before stretching to increase the extensi- of a physical agent may be appropriate. Looking at the bility of superficial soft tissues and promote a more effec- effects of a particular physical agent on these conditions is tive and safe increase in soft tissue length when the the next step. Having determined which physical agents stretching force is applied. can promote progress toward determined goals, the clini- When considering the application of a physical agent, cian should then decide which of the potentially effective one should first check the physician’s referral, if one is interventions would be most appropriate for the particular required, for a medical diagnosis of the patient’s condition patient and his or her current clinical presentation. In and any necessary precautions. Precautions are condi- keeping with the rule of “Do no harm,” all contraindi- tions under which a particular treatment should be cated interventions should be rejected and all precautions applied with special care or limitations. The therapist’s adhered to. If several methods would be effective and examination should include but should not be limited to the patient’s history, which would include information about the history of the current complaint, relevant Highest / First priority medical history, and information about current and ex- pected levels of activity and participation; a review of systems; and specific tests and measures. Examination 1A. Primary 1B. Problem findings are evaluated to establish a diagnosis, a progno- underlying most likely to sis, and a plan of care, including anticipated goals. Given problem respond to an understanding of the effects of different physical treatment agents, the clinician can assess whether intervention us- ing a physical agent may help the patient progress toward anticipated goals. The clinician can then determine the 2. Treatments that treatment plan, including the ideal physical agents and address more than one problem simultaneously intervention parameters, if indicated. This plan may be modified as indicated through ongoing reexamination and reevaluation. The sequence of examination, evalua- tion, and intervention is followed in the case studies 3. Symptomatic described in Part II of this book. treatment only CHOOSING A PHYSICAL AGENT Physical agents generally assist in rehabilitation by affect- ing inflammation and tissue healing, pain, muscle tone, Lowest / Last priority or motion restrictions. Guidelines for intervention selec- tion based on the direct effects of physical agents are FIG 1-2 ​Prioritizing goals and effects of treatment.  The Physiology of Physical Agents CHAPTER 1 11 applied in conjunction with or during the same treatment Goals and effects of treatment session as other interventions. Interventions are generally combined when they have similar effects, or when they address different aspects of a common array of symptoms. Contraindications and precautions For example, splinting, ice, pulsed ultrasound, laser light, PSWD, and phonophoresis or iontophoresis may be used during the acute inflammatory phase of healing. Splinting can limit further injury; ice may control pain Evidence for physical agent use and limit circulation; pulsed ultrasound, laser light, and PSWD may promote progress toward the proliferation stage of healing; and phonophoresis and iontophoresis may limit the inflammatory response. During the prolif- Cost, convenience and availability eration stage of healing, heat, motor level ES, and exercise may be used, and ice or other inflammation-controlling FIG 1-3 ​Attributes to be considered in the selection of physical interventions may continue to be applied after activity to agents. reduce the risk of recurring inflammation. Rest, ice, compression, and elevation (RICE) are fre- quently combined for the treatment of inflammation and could be applied safely, then evidence related to these edema because these interventions can control inflamma- interventions, ease and cost of application, and availabil- tion and edema. Rest limits and prevents further injury, ice ity of resources should also be considered. After selecting reduces circulation and inflammation, compression ele- physical agents, the clinician must select the ideal treat- vates hydrostatic pressure outside the blood vessels, and ment parameters and means of application and must elevation reduces hydrostatic pressure within the blood appropriately integrate the chosen physical agents into a vessels of the elevated area to decrease capillary filtration complete rehabilitation program. pressure at the arterial end and facilitate venous and lym- Because physical agents have differing levels of associ- phatic outflow from the limb.62-65 ES may be added to this ated risk when all other factors are equal, those with a combination to further control inflammation and the for- lower level of risk should be selected. Physical agents with mation of edema by repelling negatively charged blood a low level of associated risk have a potentially harmful cells and ions associated with inflammation. dose that is difficult to achieve or is much greater than the When the goal of