Physical Therapy—The Science

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CHAPTER 106 Physical Therapy—The Science

Eric A.K. Mayer, MD, Julie Fritz, PhD, PT ATC

Physical therapy has long been the “backbone” in the care continuum to return patients with spine disorders or injuries to full function. Physical therapy lies at the heart of preoperative “conservative care,” postoperative rehabilitation, and the tertiary functional restoration. The specific therapeutic his interventions may very, but the goals of increasing range of motion and increasing strength are shared goals in each of these time periods. Injuries to the spine are often more complicated than musculoskeletal injuries to the extremities, and multiple factors can confound straightforward physical rehabilitation of muscles, joints, tendons, and ligaments. Spine injuries often do not respond to the standard recovery timeline seen in musculoskeletal injuries in the extremities. Factors that complicate spinal injury recovery include statutory vagaries, financial disincentives, charismatic practitioners, false beliefs, and erratically applied medical evidence.^1,² Scientific literature has helped to assuage fears about rehabilitation and functional capacity/limitation after injury. It is now recognized that minimizing bed rest and maximizing early activity return is not harmful and shows the greatest beneficial functional outcomes over “restful waiting.”^3,⁴ Moreover, rehabilitation based on measured, progressive increases in resistance has demonstrated improvement in return to function, employment, social role, and reduction in symptoms.⁵^–¹⁰ Unfortunately, there is an acknowledged lack of level I and II data as to the best type of therapeutic exercise to limit functional loss and to decrease the probability of chronicity. In the absence of clear and consistent research, rehabilitation has often relied on traditional patterns of practice that are not always evidence based. These traditional patterns have, at times, involved excessive reliance on modalities and passive intervention, rather than principles of active motion and strengthening.^11,¹² This chapter is a brief primer for the spine surgeon to maximize the chances of full benefit from conservative care and decrease the chances of creating a functional failure that progresses to disability.

Overview—Two Steps Forward, One Step Back

The past two decades have seen remarkable advances in spine surgical techniques and technology such as motion-sparing technology, muscle-sparing techniques, smaller surgical incisions, biomechanical stability, biologic restoration, and faster postsurgical recovery. Unfortunately, over the past 10 years total spine expenditures have increased by 82% while corresponding health status measures have declined. In 2006 (last available data), nearly 30% of the population reported physical limitations related to spinal problems (up from 20% in 1997).¹³ Disabling, benign spinal pain medication costs increased 139% nationwide, and the number of physician visits increased almost 300% in North Carolina.^14,¹⁵ Approximately 65% of workers receiving a fusion in Washington State were disabled 2 years after surgery.¹⁶ Finally, the years 1991 to 2006 saw a staggering increase in “injured” workers dropping out and ceasing their societal contributions. The number of musculoskeletal disease claims awarded Social Security Disability Insurance rose from 15% to nearly 30%, making it the second highest group behind mental health.¹⁷ These metrics are an important indicator that physicians (and spine specialists in particular) are failing to provide the type of care that encourages function.

The answers behind this epidemiologic trend are not forthcoming. Cady and colleagues ¹⁸ showed in 1979 that stronger, more physically fit individuals have fewer injuries. Their conclusion was that “… physical fitness and conditioning are preventive of back [spinal] injuries… .”¹⁸ Subsequent studies have shown that strong, aerobically fit individuals have fewer absences from “heavy” vocational or avocational activity. Furthermore, when physically fit individuals are injured, they tend to return to function more rapidly.¹⁹^–²² Even with these findings in mind, there remains a lack of consensus on achieving flexibility, strength, balance, and overall fitness when rehabilitating spine injury. One consistent confounder has been the so-called “cumulative trauma” theory. This theory postulates that repetitive loading of the spine or postural effects such as driving significantly contribute to disc and facet joint degenerative changes that are themselves associated with pain. Recent studies seem to find little evidence that “cumulative trauma” is independent of genetics for sedentary work, heavy work, body weight, or work position.²³^–²⁵

These epidemiologic data strongly suggest that physical fitness, as well as the progressive resistance necessary to maintain fitness, is protective of injury and poses minimal independent risk of injury. Longitudinal industrial analysis of workers lifting over 5000 kg net per shift (observed over 2 years) concluded that although low back pain development was multifactorial, the best predictor of future back pain was decreased physical fitness at time zero.¹⁰ This study, although informative for preinjury planning, does not address postinjury treatment. The remainder of this chapter is devoted to discussing what to do after an injury has occurred. Physical therapists have several modes of treatment at their disposal, each with variable evidence as to efficacy. These modes include spinal manipulative therapy, stabilization (core exercise protocol), directional (McKenzie-type) exercises, and general reconditioning/strengthening exercises. In addition to the therapies listed earlier, cognitive behavioral therapy has an important, adjunctive role in rehabilitating a patient whose psychosocial factors prevent or delay improvement. Additionally, the thoughts and beliefs of clinicians including physical therapists and physicians can play an important role in patient recovery. Clinicians’ thoughts and beliefs may be the most important independent predictor of a patient’s perceptions of his or her own disability.²⁶ In general, clinicians who want to manage expectations (to avoid patient anger and frustration if there is subsequent residual pain) should be wary of perpetuating beliefs that pain indicates ongoing harm or injury. There is a fine line between managing expectations of residual symptoms and feeding patient beliefs of permanent impairment. False ideas about persistent disability reinforced by interactions with clinicians are difficult to extinguish and may lead a patient to enter into expensive, tertiary-level care or the disability system.^27,²⁸ In summary, active physical reconditioning through physical therapy remains the mainstay of functional return after injury, with clinicians needing to remain cognizant of false perceptions of disability that may also need rehabilitation.

Evaluation and Treatment: Importance of Classification

One problem in developing evidence-based treatments for spinal conditions has been difficulty identifying the anatomic structure responsible for a patient’s symptoms. In fact, up to 90% of patients with back pain cannot be given a precise diagnosis on the basis of pathology.²⁹ Instead, nonspecific diagnostic labels like “lumbago” or “lumbar strain” are common. This group of patients has historically been managed as a homogenous entity. More recently, many practitioners and some researchers have demonstrated that patients with nonspecific back pain are not a homogeneous group but instead consist of subtypes of patients who can be classified on the basis of specific signs and symptoms noted during the examination.^30,³¹ Evidence suggests that patient classification that allows specifically tailored treatment based on a patient’s back pain subtype improves outcomes compared with giving all patients a stereotypical one-size-fits-all treatment regimen.³²^–³⁴

Some investigators have proposed a treatment-based classification system for the evaluation and treatment of patients with low back pain.^30,³⁵ This system uses information gathered from the physical examination and from patient self-reports to guide patient management. Three basic levels of decision making or classification are required: (1) the patient is screened for medical “red flags” to ascertain his or her suitability for rehabilitation, (2) the acuity of the low back condition is determined, and (3) the patient is evaluated and placed into a classification that determines the treatment approach to be used.

Medical “red flags” are signs or symptoms that may indicate a serious underlying pathology such as spinal neoplasm, cauda equina syndrome, or infectious process. Specific signs and symptoms that have been identified include a history of cancer, widespread and progressive neurologic loss, unexplained weight loss, fever, chills, or a recent history of an infectious condition. More complete explanations of medical red flags for consideration in individuals with back pain can be found in other sources.³⁶

The acuity of a patient’s back pain is an important consideration in determining the most appropriate treatment. Acuity is not simply a matter of number of days since the onset of symptoms but is also based on the nature of the patient’s course of back pain and the examination findings. The natural history of back pain tends to be one of periods of exacerbation and remission.³⁷ A patient who experiences a new exacerbation may be considered in an acute stage. Patients in an acute stage will also have examination findings related to a classification category indicating the need for specific type of intervention (e.g., directional exercise, spinal manipulative therapy, stabilization exercises) as outlined later. In contrast, patients reporting persistent, unremitting low back symptoms and related disability are considered to have chronic symptoms. These patients often lack objective examination findings that indicate a specific classification and may be best managed with a strengthening and conditioning treatment strategy. Patients with chronic symptoms may also be more likely to have psychosocial risk factors that may respond favorably to a combination of physical and cognitive-behavioral approaches to rehabilitation.³⁸

Spinal Manipulative Therapy

Spinal manipulative therapy is a treatment approach to spinal pain that has been practiced by some medical practitioners for several centuries. Research studies and evidence-based practice guidelines support early, limited use of spinal manipulation.³⁹ Research further indicates that the subgroup of patients with back pain who may be most likely to benefit from spinal manipulation are those with recent onset of primary back pain or new exacerbation of axial pain without pain symptoms extending distal to the knee(s).^40,⁴¹ Additionally, the presence of spinal stiffness, greater degrees of hip mobility in internal rotation, and low levels of psychologic distress may indicate a patient will benefit from spinal manipulation, especially when fear and avoidance beliefs are absent.⁴² Patients with the previously mentioned examination findings have been shown to respond favorably to a combined rehabilitation approach that includes spinal manipulation.⁴³

Spinal manipulation treatment involves the application of a high-velocity, low-amplitude thrust force to the spine. Although it is not necessary for a successful manipulation, these techniques often result in an audible cavitation or “pop.”⁴⁴ A variety of specific spinal manipulation techniques have been described by different types of clinical practitioners. Some have promoted the use of low-velocity, nonthrust procedures commonly called “mobilization procedures.” Recent research suggests that the use of a high-velocity, thrust manipulation technique is more likely to benefit patients fitting the “acute” classification category. The differences among high-velocity manipulation procedures appears negligible clinically.⁴⁵ The goal of spinal manipulation treatments is to reduce the patient’s pain and permit the patient to proceed to a general conditioning/strengthening program. Therefore when applied to the appropriate patient, spinal manipulation may only be necessary for one to two treatment sessions before symptoms improve to a point where more aggressive exercises can be employed.⁴³ Physicians should understand that it is appropriate to begin flexibility and strengthening exercises concomitantly with spinal manipulation treatment.

Spinal Stabilization Exercises

Strengthening the muscles of the lumbar spine is often the focus of exercise programs for patients with back pain. Research has indicated that the properties of muscular endurance, muscle balance, and neuromuscular control may be important considerations for rehabilitation of the trunk muscles.⁴⁶^–⁴⁸ Some patients with LBP have also been observed to have morphologic changes that include atrophy and fatty infiltration in the lumbar multifidus and erector spinae muscles.^49,⁵⁰ Stabilization exercise programs are typically designed to address the deficits in strength, endurance, and function of the trunk musculature in patients with prolonged back pain and functional impairment. It is thought that improvements in trunk muscle function lead to a decrease in pain and disability by improving the motor control of spinal segments during movement. This hypothesis has been supported by studies showing stabilization exercise improving trunk muscle mobility, strength, and both radiologic and electromyographic morphology in individuals with low back pain.⁵¹^–⁵³

What the most effective stabilization exercise regimen is remains a subject of intense debate in the literature. Some studies have demonstrated the value of trunk stabilization exercises on specific deep muscles, particularly the transversus abdominis and multifidus.^52,⁵⁴ Other studies have demonstrated equivalence between stabilization exercise and more general trunk strengthening exercises.^55,⁵⁶ A systematic review of current literature concluded that stabilization exercises targeting the deep trunk muscles are more effective than usual care, but it was unclear whether or not they were more effective than other active/strengthening rehabilitation interventions.⁵⁷ These findings seem to support the identification of patient subgroups likely to benefit from a particular exercise approach. Ongoing research indicates that subgroups who benefit from a focused program include younger individuals (younger than age 40), those with greater overall flexibility, those with lumbar segmental hypermobility, and those with possible physical examination signs suggesting instability.^58,⁵⁹