Early evidence of a rehabilitation approach to the injured person or worker dates back to the Egyptians under Ramses II in 1500 BC where organized treatments of injured workers, fees for treatment, and compensation for injury were established.⁵ The development of more expertise and a more rational treatment and management approach of pain was delayed until the birth of the field of anesthesia in the 1840s and the isolation and synthesis of morphine by Serturner in 1806 and salicylates from willow bark in the late 1800s.⁶ The modern development of a rehabilitation model evolved only after World War I and World War II with the birth of the fields of physical and occupational therapy as a means to “rehabilitate” injured returning soldiers.⁷ Pain rehabilitation developed in the context of evolution of the medical specialties of physical medicine and rehabilitation, anesthesia, psychiatry, and occupational medicine during the 20th century. John Bonica championed a more comprehensive “multidisciplinary” approach in the United States in 1947 and later at the University of Washington in 1960.⁸ Wilbert Fordyce, a psychologist and collaborator of Bonica, incorporated operant conditioning and other behavioral approaches with more specialized 8-week inpatient programs in the late 1960s. In 1982, John Loeser formalized a more “structured program” at the University of Washington, a 3-week daily program, which has become a model for “interdisciplinary” treatment. A more biopsychosocial approach to pain rehabilitation has also been facilitated by the merging of behavioral and cognitive fields and the subsequent cognitive-behavioral approach to the assessment and treatment of pain in the 1980s and 1990s.^9,10,11 A proliferation of pain treatment facilities was seen between 1980 and 1995 and included the advancement of interventional procedures.¹² A more recent conceptualization of pain focuses on behaviors within the pain system, a biopsychomotor model of pain, which incorporates three interdependent behavioral subsystems: (1) communicative, (2) protective, and (3) social response behaviors.¹³ This model assumes that a pain system can only be adaptive if the sensory component of the pain system is accompanied by behaviors designed to act on the source or cause of injury or illness. This may help to explain the wide variability observed in pain behaviors seen across different patients despite relatively similar levels of reported pain intensity and objective tissue pathology. The biopsychomotor model of pain can be extended to include behavioral factors such as communicative behavior (grimacing), protective behaviors (i.e., withdrawing a limb from the fire), and behaviors designed to elicit social responses (i.e., empathy and solicitous behavior from others). This model, like the biopsychosocial one, emphasizes that dysfunction may develop in behavioral systems separate from pain sensation, and subsequent treatments targeting pain behavior would more likely lead to greater clinical outcomes and provide a more pragmatic and inclusive model for the spectrum of pain rehabilitation (Fig. 90.1).

Functional restoration (FR) programs, based on a return-towork model, evolved along with advancements in occupational medicine beginning in the 1970s. Prior to this, programs of “habit training” focused on restoring workers affected by disease or injury in the 1920s and later by the incorporation of vocational rehabilitation mandated at the federal level in 1923 and the Vocational Rehabilitation Act. In the 1950s, more objective measures were used to track progress and measure outcomes and served as the starting point for more formal work conditioning and work hardening programs championed by Lillian Wegg and Florence Cromwell.^14,15 In the 1970s, work hardening emerged as a formal industrial management service¹⁶ and adopted a similar multidisciplinary approach used in the management of chronic pain and disability. Standardized work stimulation equipment, assessment, and treatment protocols were incorporated into standard practice in the 1980s and led to formal accreditation by the Commission on Accreditation of Rehabilitation Facilities (CARF) in the late 1980s and early 1990s.^17,18,19

Gatchel et al.²⁰ described eight classic critical elements of an FR approach which serves as the foundation for most multiand interdisciplinary rehabilitation-based programs. Elements include quantification of physical deficits on an ongoing basis, psychosocial and socioeconomic assessment used to individualize and monitor progress, and an emphasis on reconditioning of the injured area or body part. The team-centered FR approach also includes generic simulation of work or activity, disability management with cognitive-behavioral approaches, psychopharmacologic management focusing on improving analgesia, sleep, and affective distress, many times detoxifying patients from medications (i.e., opioids or benzodiazepines).²⁰

A pain rehabilitation model can be applied to the entire spectrum of pain conditions, from acute musculoskeletal injuries, to subacute and recurrent injuries aggravated by poor ergonomics and/or physical impairments, to more complex chronic pain conditions where interplay of biologic, psychologic, and social influences is more apparent. Pain rehabilitation is based on a structured, individualized approach. The formal assessment identifies specific problems and needs most relevant to the patient and relates the problem to impairments and psychosocial factors, selecting appropriate measures to monitor progress and treatment. The rehabilitation program includes planning and coordinating various interventions with a focus on treating the specific impairments by restoring function and identifying compensatory strategies. Additionally, addressing activity limitations by addressing environmental and personal factors may help in restoring patients to previous levels of functioning and preventing or limiting disability.¹

A traditional definition of rehabilitation, based on a biomedical model, places the concept of rehabilitation as a secondary intervention, used to restore patients to their previous level of (residual) physical, psychologic, and social functioning, and, if possible, return them to (modified) work.²¹ Waddell and Burton²² question this assumption in that the biomedical definition assumes that disability is a “matter of permanent impairment,” that sickness and disability imply an incapacity to work, that rehabilitation focuses on “irremediable permanent impairment,” and that rehabilitation is a second-stage process following acute medical management and only is carried out after treatment ceases. Waddell and Burton²² have implied this may be inappropriate in that in many chronic pain conditions (i.e., low back pain), objective factors (pathology and impairment) accounts for a small part of the incapacity. These chronic conditions are characterized more by “symptoms and distress” than tissue abnormality.²² A number of biopsychosocial risk factors (i.e., lower level of education, higher preoperative pain, low work satisfaction, longer duration of sick leave, somatic complaints, and passive avoidance coping) have been identified as predictors of poor outcomes after surgical interventions contributing to loss of function, increased disability, and persistent elevated levels of subjective reports of pain.^23,24 These biopsychosocial risk factors may serve as important potential targets for pain rehabilitation.

Pain rehabilitation also involves the coordination of a number of important stakeholders involved in the care of the individual patient or worker. Stakeholders may include various health care providers, managed care organizations and insurers, the workers’ compensation carrier, society, the individual patient, and family members. This complex health care process and related list of stakeholders involved may sometimes add, as described by Shultz et al.²⁵ and Gatchel et al.,²⁰ a political dimension to the individual patient’s assessment and treatment process. Success in treatment may vary depending on stakeholder and may indirectly lead to antagonistic, confrontational, and misinterpreted feelings by the patient suffering with pain. Criteria of success may vary significantly depending on whether it is assessed by the patient or by society in general (Fig. 90.2). Many times, contrary to what is seen in other areas of clinical medicine, the pain rehabilitation clinician may find himself or herself in a potentially conflicting role in the treatment of patients with chronic pain (Table 90.1). The focus of care should remain on providing appropriate clinical services, serving as a patient advocate or adjudicator, without crossing ethical boundaries resulting in harm to the client.²⁶

This chapter focuses on an overview of assessment and treatment strategies included in a pain rehabilitation-based approach to acute and chronic pain conditions. As part of the clinical continuum, the more comprehensive and integrated treatment approaches commonly referred to as multidisciplinary, interdisciplinary, and/or FR²⁷ will be examined. Important psychological factors related to chronic pain and disability, the continuum of treatment models from more acute to integrative approaches, specific responsibilities of members of a pain rehabilitation team (i.e., physical and occupational
therapist, psychologist, relaxation therapist, and vocational specialist), and an overview of more specific work rehabilitation approaches including work conditioning, work hardening, and functional capacity testing will be reviewed.

The biomedical model assumes a causal relationship between a specific physical pathology and the presence or intensity of pain symptoms. It emphasizes the importance of eliminating pain by restoring normal function in the organ or body part from which pain is thought to emanate. Although the more disease-based biomedical model enabled the medical sciences to flourish and improved our ability to treat infection and other disease processes, its fundamentally limited scope led to less profound success and relative treatment resistance in the treatment of many chronic pain states. A biomedical model may be more advantageous in treating more acute pain states, where interventional procedures, pharmacotherapy, and surgical interventions may lead to recovery of pain or hasten time to recovery. But the biomedical model poorly addresses related mental health issues and frequently relies on dualistic decision pattern, whereby if the patient does not respond to an intervention, then the pain may be not be “real” or just “in their heads.”³¹ Many more complex pain conditions remain resistant to a purely biomedical approach (i.e., chronic low back pain, neuropathic pain, and fibromyalgia).³² George Engel³³ helped to shift the thinking from a purely biomedical model of disease management to a more comprehensive biopsychosocial model of illness. Recently, the World Health Organization³⁴ has embraced a biopsychosocial model of disability (Fig. 90.3), which incorporates a dynamic interaction between the individual health condition and contextual factors.

The pain rehabilitation approach is based on a fundamental understanding of the individual’s unique condition as it relates to (1) impairment, (2) disability, and (3) functional limitation. Impairment is the loss of normality psychologically, physically, or functionally at the level of the organs and body systems.³⁵ Examples of physiologic impairments include muscle weakness, loss of range of motion, and pain. Disability is a restriction or lack of ability to perform activities due to related impairments such as inability to function in a specific vocation, as a spouse, student, or parent. Functioning has been described as an umbrella term for body functions, body structures, activities, and participation, denoting a positive interaction between the individual or patient and contextual factors (i.e., background of the individual’s life and current situation). Functional limitation is a deviation from the normal behavior of performing activities of daily living (ADLs) and may include problems with transfers, standing, ambulation, running, and stair climbing.³⁵ A formal model proposed by the International Classification of Functioning, Disability and Health integrates the individual components into a biopsychosocial-based model where a “health condition” is substituted by “chronic pain” (Fig. 90.4). Chronic pain is affected by body function, activities, and participation as well as influences from the environment and personal factors.

A patient-centered approach is necessary if one is to effectively address these important individual concepts. A teamcentered approach focuses on helping patients to achieve individual goals, which enable them to improve physical and psychosocial function, decrease pain, and improve quality of life. By working together, the rehabilitation team is able to help patients achieve better outcomes than could be achieved
by an individual practitioner or intervention (i.e., surgical procedure, injection, pharmacotherapy). Basic treatment goals of both acute and chronic pain rehabilitation programs focus on functional improvement; improved abilities to perform ADLs, return to leisure, sport, or vocational activities; and improved pharmacologic management of pain and related affective distress (Table 90.3).

A pain rehabilitation approach encompasses a wide range of treatment options including more directed therapies for acute pain conditions to more comprehensive and collaborative multi- and interdisciplinary approaches (Table 90.4).

Decision making in pain rehabilitation has been found to incorporate common decision values shared by the team members, worker, and stakeholders. Shared “general values,” as described by Loisel et al.,⁶⁰ are those that stress work is therapeutic, pain is multidimensional, and interventions should be graded. These values should in turn be shared by the team members, the worker, and stakeholders facilitated by reassurance and the delivering of a single message as a way of more successfully returning a patient to work or previous level of function.⁶⁰ These same values can be applied to the many barriers presented to the individual patient and stakeholder (Table 90.5).

Assessment of patients prior to entering a rehabilitation program is based on a comprehensive examination of physical, psychological, and social or relevant vocational factors. Also, the evaluating clinician must work to develop trust and rapport with the patient in order to understand barriers to recovery (i.e., contentious relationships involving family, employer, case manager, and/or the legal system) that may potentially lead to a delay or reduction of clinical improvement. Many times, the success of developing that relationship starts at the initial evaluation. Understandably, patients undergoing a rehabilitation program are often asked to make significant changes in the ways they cope with pain and function. Readiness to make such important changes has been found to be associated with treatment success,^61,62 and readiness to self-manage pain increases from pre- to post-MPC treatment.⁶³ Based on the transtheoretical model of behavior change, individuals are seen to progress through a number of stages involving decisions about change and include precontemplation, contemplation, action, maintenance, and acceptance phases.⁶⁴ These basic concepts are important for the physician to explore during the evaluation and often become a focus of discussion between other potential treatment disciplines (i.e., pain psychologist, physician, and vocational counselor) when deciding whether the patient is an appropriate candidate for treatment. The pain rehabilitation clinician must be consistent and clear in promoting exercise and activity as essential, safe, and effective for the correction of functional impairments. The clinician must also be aware of various fears, negative attitudes, financial, and vocational stressors many chronic pain working and nonworking patients
are sometimes struggling with and be able to confront the patients on these issues in an open and understanding manner (Table 90.6).⁶⁵