The McKenzie Method of Mechanical Diagnosis and Therapy for the Classification and Rehabilitation of Spinal Problems

Thomas J. Lotus

Richard Rosedale

LEARNING OBJECTIVES

After reading this chapter you should have some understanding of:

The definitions and criteria of the McKenzie Method of Mechanical Diagnosis and Therapy (MDT) classifications of postural, dysfunction, and derangement syndromes and the OTHER MDT subgroups.
The principles of management of the postural, dysfunction, and derangement syndromes.
The application of the four stages of the management of derangement with a specific clinical example.
The concepts of “force progression” and “force alternatives” and their relevance in the MDT assessment and management.
The practice and application of some example lumbar and cervical procedures.
The highlights of some of the supportive studies regarding MDT.
The implications of the MDT system for the global management of musculoskeletal conditions.

“If a condition is very common, persistent, often episodic…it is time patients were fully empowered to deal with these problems in an optimal and realistic fashion. As clinicians, we should be offering this empowerment to our patients.”

–ROBIN MCKENZIE

Introduction

Spinal pain has a well-documented natural history that is persistent, recurrent, and episodic.¹ The goal of rehabilitation should, therefore, be oriented toward enabling patients to address and manage these problems not just for their current episode but potentially over their lifetime. To serve that purpose, spinal rehabilitation needs to promote self-efficacy from the initial patient-therapist encounter through to discharge. Unfortunately, such efforts are often delayed when clinicians provide passive, palliative comfort care while waiting for things to “calm down” before the active and rehabilitative component is introduced. The combined fears of patient and practitioner may be roadblocks to the exploration of patient self-generated movements for therapeutic purposes. The specter of dependency and deconditioning of physique and psyche is raised when patients are passive recipients of care. Any delay in patient active participation is a delay in developing patient empowerment through self-management skills, the ultimate goal of rehabilitation.

This chapter introduces the McKenzie Method of Mechanical Diagnosis and Therapy (MDT) assessment, classification, and management of cervical and lumbar spinal problems, using predominantly patient-generated movements. Whether acute or chronic, MDT concepts and principles promote independence in self-care from day 1, without passive therapy detours on the rehabilitation road to recovery. If the practitioner and patient choose to make self-generated movement and positioning as the centerpiece of care and the patient is educated accordingly regarding movement and positioning strategies, then the majority of patients will have the potential to rapidly ameliorate complaints.

This chapter attempts to introduce the reader to some of the foundations and principles of MDT so they can appreciate that, with appropriate training, the approach can be used as a comprehensive and reliable system for managing all musculoskeletal problems. This brief overview focuses on the fundamentals of the MDT classification and some core aspects of the management in the spine. The reader is encouraged to keep in mind that all the principles and clinical reasoning are also applied to extremity problems, and the research base for MDT in the extremities is expanding rapidly,²^,³^,⁴ with the implications of a self-management approach being just as profound as they are in the spine.

Further study is encouraged by means of the texts authored by Robin McKenzie⁵^,⁶^,⁷ and postgraduate study provided by the McKenzie Institute International and country-specific branches.⁸ We close the chapter with a brief consideration of the research literature pertaining to MDT. The reader is directed to the reference list on the McKenzie Institute International website⁹ to review the up-to-date literature regarding the McKenzie method. MDT Classification: Definitions and Criteria MDT is not just a method of assessment or a selection of patient exercises and specific clinician techniques; it is a comprehensive biopsychosocial framework that clinicians can use to screen their patients, reliably categorize them, and provide a tailored management and preventative program. It is well discussed in the literature that applying interventions to patients without reference to their specific presentation and without any attempt to classify or subgroup patients can lead to suboptimal care.¹⁰ Valuable health care resources can potentially be wasted when clinicians attempt to “fix” the patient without classifying/diagnosing first. This can lead to a prolonged
cycle of randomly applied treatment after treatment, where the clinician draws one intervention after another from their “toolbox” in the hopes that one of the therapies will eventually be effective. This can be a frustrating experience for both the clinician and the patient, not to mention the other parties that may have a vested interest in the patient’s recovery. The choice of the specific classification/diagnostic system is one that clinicians need to make very carefully, weighing the evidence, as well as the pros and cons in regard to their patients and the broader implications for health care. It is also important that clinicians choose a system that considers the psychosocial components of spinal pain and the potential barriers to recovery that may accompany different presentations.

So, before we launch into the rehabilitation process, we need to know what specific interventions and exercises to provide for which particular patients and we need some means of screening and evaluation in order to effectively do this. MDT provides this means; it does not start with rehabilitation exercises, it starts with a detailed history and physical examination that allows the clinician to appropriately recognize not only clinical patterns (syndromes and subgroups) of mechanical and symptomatic responses to loading, but also psychosocial issues that may adversely impact the outcome. The majority of patients will have a recognized pattern that will respond rapidly to mechanical (movement and positioning) intervention,¹¹ some will have a pattern that will respond more slowly,¹² and some will be flagged as having presentations that will not respond to conservative intervention and need referral and further investigation.¹³ The key to successful rehabilitation is finding which classification the patient’s symptoms conform to and then introducing the matched intervention.

Many articles¹⁴^,¹⁵^,¹⁶ still refer to McKenzie’s three “mechanical syndromes” as if they were the sole focus of the system. The recognition and description of these syndromes is certainly unique to MDT. Robin McKenzie was the first to describe these specific patterns of musculoskeletal presentation, but he recognized that they do not in themselves entail the full breadth of possible classifications. Within the McKenzie system, there are OTHER subgroups, and over the decades, as the system has been updated and fine-tuned, these OTHER subgroups have been formalized. Now these subgroups have established definitions and criteria that complete the diagnostic options available to the MDT clinician for the spine (Table 17.1) and for the extremities.

We will start by discussing the three patterns of mechanical and symptomatic responses to loading that McKenzie recognized, noting the definitions, criteria, and characteristics. The three syndromes are:

Derangement syndrome
Dysfunction syndrome
Postural syndrome

It is first to be noted that these syndromes, though very definitive in their criteria, are nonpathoanatomic classifications; they are not specific to a particular structure or pathology, but are clinical presentations that lead onto targeted therapeutic interventions. There has been a steady movement away from the use

of pathoanatomic diagnosis for conservative care clinicians in the spine. The reasons for this change are numerous, including the lack of validated diagnostic criteria and subsequent diagnostic inaccuracy,¹⁷ the poor reliability and validity of orthopedic diagnostic testing,¹⁸ the lack of relationship between abnormal imaging finding and pain,¹⁹ and the negative impact on outcomes of the patient interpreting the information about potential pathoanatomic sources of symptoms.²⁰ All these factors have hindered the clinician’s ability to make a precise diagnosis and hence a logical and effective management pathway.

Table 17.1 Table of OTHERs

Category	Clinical Findings (Red Flags)	Clinical Examples
Cancer	Age > 55, history of cancer, unexplained weight loss, progressive, not relieved by rest	May be primary site of metastases
Cauda equina/cord compression	Bladder retention, bowel incontinence, saddle anesthesia, global or motor weakness in legs. Clumsiness in legs
Spinal fracture	History of severe trauma, older age, prolonged steroid use OR young, active with sport-related back pain	Compression fracture, stress fracture of the pars
Spinal-related infection	Fever, malaise, constant pain, all movements worsen	Epidural abscess, discitis, transverse myelitis
Vascular	Vascular disease, smoking history, family history, age over 65, male > female	Abdominal aortic aneurysm, cervical artery dysfunction
Subgroup	Definition	Criteria (Common)	Clinical Examples
Chronic pain syndrome	Pain-generating mechanism influenced by psychosocial factors or neurophysiologic changes	Persistent widespread pain, aggravation with all activity, disproportionate pain response to mechanical stimuli, inappropriate beliefs and attitudes about pain
Inflammatory	Inflammatory arthropathy	Constant pain, morning stiffness, excessive movements exacerbate pain	RA, seronegative arthritis, ankylosing spondylitis
Mechanically inconclusive	Unknown musculoskeletal pathology	All other classifications excluded. Symptoms affected by positions or movement but no recognizable pattern identified or inconsistent symptomatic and mechanical responses on loading
Mechanically unresponsive radiculopathy	Radicular presentation consistent with a currently unresponsive nerve root compromise	Symptoms presenting in a radicular pattern in the upper or lower extremity. Accompanied by varying degrees of neurologic signs and symptoms. There is no centralization and symptoms do not remain better as a result of any repeated movements, positions, or loading strategies
Postsurgery	Presentation relates to recent surgery	Recent surgery and still in postoperative protocol period
SIJ/PGP	Pain-generating mechanism emanating from the SIJ or symphysis pubis	Three or more positive SIJ pain provocation tests have excluded the lumbar spine and hip	If related to pregnancy: PGP
Spinal stenosis	Symptomatic degenerative restriction of spinal canal or foramina	Lumbar spine: older population, history of leg symptoms relieved with flexion activities and exacerbated with extension, long-standing loss of extension Cervical spine: arm symptoms consistently produced with closing foramen, abolished or decreased with opening	Lumbar stenosis, cervical lateral foraminal stenosis
Structurally compromised	Soft tissue and/or joint integrity or bony changes compromising joint integrity	Mechanical symptoms (range of motion restricted, clunking, locking, catching). May have a sensation of instability. Long history of symptoms or trauma, irreversible with conservative care	Painful structural scoliosis, painful osteoporosis, grade 3-4 spondylolisthesis, upper cervical instability—RA
Trauma/recovering trauma	Recent trauma associated with onset of symptoms	Recent trauma associated with onset of constant symptoms/recent trauma associated with onset of symptoms, not improving and pain intermittent	Post-whiplash
PGP, pregnancy-related girdle pain; RA, rheumatoid arthritis; SIJ, sacroiliac joint.

Classifying Derangement Syndrome

The derangement syndrome is reported to be by far the most common clinical presentation of spinal problems.²¹^,²² Prevalence rates vary depending on the chronicity, but with trained therapists in different settings, it has been shown to be between 60% and 78% in the lumbar spine.¹¹^,²¹^,²²^,²³^,²⁴^,²⁵ A 2019 survey of 750 spinal patients from 15 different countries found a prevalence rate of 73% in the lumbar spine.²² In the cervical spine, the rates are reported to be between 72% and 87%.²¹^,²³^,²⁶ The 2019 survey that included 181 cervical patients confirmed the high prevalence with a finding of 82%; the numbers seem consistently high.²² It is, therefore, very frequently seen in clinical practice and in principle would be important for the clinician to identify, as by its nature the patient with a derangement will respond positively and rapidly to end range exercise. Rehabilitation should be brief, relatively simple, and effective.¹¹

By definition, a presentation of derangement has a “directional preference” and a directional preference is only found with the presentation of derangement.² So what exactly is a “directional preference” and how do clinicians go about finding one? Directional preference has been defined in various ways in the literature. Perhaps the most common definition as quoted in the 2018 systematic review of directional preference and centralization²⁷ is, “Directional preference is defined as the repeated movement that produces centralization, or an abolition or decrease in symptoms, or an increase in restricted range of movement.” This quote is from the text by McKenzie and May.⁶ The positive changes that occur should be lasting and result in the ultimate resolution of the presenting problem.

The experienced MDT clinician will use repeated movements or sustained positions in different directions and planes, with varying loading strategies in order to discover the specific direction. For example, in the lumbar spine, it may be a movement in the sagittal plane (flexion or extension), lateral movements, or combinations of sagittal and lateral that become established as the directional preference. A high proportion of those that are derangements in the spine will also demonstrate centralization.²⁴ Centralization is defined as the abolition of distal and spinal pain in response to repeated movements or sustained postures.²⁷ The location of the pain is an essential guide during the examination process and it is the most distal pain that is tracked meticulously for a location change. If, during the assessment, pain moves to a more distal location and remains there, that particular movement or posture is stopped; this is referred to as peripheralization.²⁸

Essentially, derangement exhibits rapid symptomatic and mechanical changes within the assessment session and these should translate into a good prognosis if the appropriate direction of movement is performed by the patient. This has been verified by multiple studies on the lumbar spine,¹¹^,²⁹^,³⁰^,³¹ with fewer studies on the cervical spine.²⁶ Those derangements that also centralize have an even more positive outlook, and this subgroup of derangement has been studied more extensively. Centralization is associated with positive outcomes in regard to both low back pain and disability in both the short and long term.³²^,³³ Additionally, centralizers were less likely to have surgery,³² tend to decrease the potential negative influences of depression and somatization on outcomes,³⁴ have a higher return to work rate and reduced ongoing health care usage.¹¹ Centralization is clearly an important variable to recognize and essential to attempt to elicit in the evaluation and treatment process. The assessment and rehabilitation of spinal pain that does not take centralization into account would be missing a large piece of the picture and would be forgoing a potentially rapid and positive outcome. But, of course, centralization and directional preference are just clinical features of derangement. Ultimately, it is the recognition and appropriate management of derangement that holds all the potential for effective and efficient spinal rehabilitation.

Classifying Dysfunction Syndrome

With derangement exhibiting a relatively variable presentation, dysfunction has a nature that demonstrates much more consistency. It is important at this point to delineate the two types of dysfunction that can present clinically. The dysfunction can be “articular” or “contractile.” An articular dysfunction is the type of dysfunction seen in the spine; it is identified by intermittent pain consistently produced at a restricted end
range with no rapid change of symptoms or range.² When the tissues are loaded appropriately and repeatedly over time, the tissues will adapt and resolution will occur.³⁵

As already stated, in spinal rehabilitation, articular dysfunction is by far the most common type of dysfunction we are dealing with; however, the prevalence rates have been reported to be low. In the 2019 survey, for the lumbar spine, the rate was only 1.8%, for the thoracic spine 2%, and for the cervical spine 1%.²² Rates may vary in different populations, but this study took into account the data from 54 clinicians in 15 countries, so one would expect that the proportions might be relatively representative of the patients seen by rehabilitation specialists across the world.

The key in the development of the dysfunction is the avoidance by the patient of moving into the painful direction with any degree of frequency. This may be secondary to an adherence to the “if it hurts, don’t do it” mind-set that pain should be avoided. Fear may also play a part in this; the patient may equate pain with tissue damage and so may be afraid of moving in any painful direction. This provides an ideal environment for dysfunction to develop, and weeks and months may go by with a lack of remodeling force being applied to the tissues and disorganization within the tissues being the sequela.

With an articular dysfunction the response should be clear and consistent, but it is important to note that this is not the same response as many clinicians may have witnessed in their own experience of “tissue dysfunction.” This is because the term “dysfunction” outside of the MDT system is used very commonly, broadly, and relatively loosely to denote a whole plethora of problems with a joint or tissue. This can lead to confusion and is likely the reason why beginners using MDT will label a greater proportion of their diagnoses as dysfunction than will experienced MDT clinicians. Once there is a full comprehension of the very specific and definitive criteria of dysfunction, then the proportion diagnosed in the spine naturally diminishes. It is interesting to note that the opposite trend has been discussed for derangements,³ where the longer experience of the clinician leads to greater recognition and a higher proportion diagnosed.

Although the short-term presentation of a dysfunction is static and unchanging, it will respond to therapeutic intervention, but slowly over weeks and months as the painful restriction of range gradually diminishes. This occurs with frequent therapeutic loading of the tissue and as it does, the pain is experienced at an end range that gradually gets closer to the normal range of motion, until eventually no pain is produced when the joint is moved to its full range.³⁵ However, because of the very low prevalence rates of this classification in the spine, it has not been subject to any scientific rigor, so the prediction of response in the spine is garnered from clinical experience and anecdote rather than published evidence. This contrasts with contractile dysfunction that is reported in the extremities and aligns with the well-documented occurrence of tendinopathies. Here the literature is extensive and so the guidance for clinicians as to the appropriate and alternative loading strategies to achieve desirable outcomes is much clearer.

Classifying Postural Syndrome

Although pain because of assuming prolonged postures may be a common experience in the general population, people experiencing pain as a result of it may not frequently present for treatment.³⁶ Because of its intermittent nature and the fact that the pain ceases once the aggravating posture is altered, it may well be considered to be an inconvenience and nuisance rather than something that needs to be, or that can be, treated. In itself, it is indeed benign, although it is proposed that it may lead to more significant musculoskeletal problems and may be an early sign of trouble to come.³⁶ As with spinal dysfunctions, there is little published work exploring postural classification,³⁶ but the prevalence is reported to be very low, only 0.2% in the lumbar spine, and none reported in the 2019 survey for the thoracic and cervical spines.²²

Fortunately, for those few, the treatment of postural syndrome is reportedly simply a matter of education and self-management, no exercises or manual therapy is required.

Sitting is frequently reported by patients to be causing, perpetuating, or aggravating lower cervical and lumbar symptoms. Reports of aggravation from sitting should raise suspicions that a change of sitting posture may have a pivotal role in recovery.

Classifying OTHER MDT Subgroups

The MDT OTHER subgroups complete the full breadth of the MDT classification system. It enables the clinician to be able to classify ALL their spinal patients while staying within the confines of MDT and thus makes the system comprehensive. This has been shown to be the case in several survey studies with over 1,200 patients with neck and back pain²¹^,²⁵^,³⁷ where the clinicians assessing consecutive spinal patients have been able to classify all within the MDT system. Although the majority of patients were
successfully classified as one of the MDT syndromes, 17% of patients were classified as one of the OTHER subgroups in these surveys. In the 2019 survey,²² the OTHER subgroups accounted for 25%, 17%, and 24% of the patients with lumbar, cervical, and thoracic pain, respectively. The most common classification in the lumbar spine of the OTHER subgroups was the mechanically inconclusive classification, followed by the mechanically unresponsive radicular syndrome classification, and then spinal stenosis (Table 17.1).

What is clear from this and previous surveys is the ability of trained clinicians to classify all their patients by using the full breadth of the MDT classification.²² This provides support for the clinical utility of the McKenzie method and makes the case for its capacity to be used as a stand-alone classification system. However, more research needs to be done in exploring classifications other than derangement syndrome. The difficulty of course is with the relatively low prevalence rate of the other classifications and the obvious challenges this would present for study recruitment. In the meantime, most of the nonderangement classifications are driven by collective clinical experience and by the evidence from non-MDT research.

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