Chapter 22. Vertebral Column

The design specification for the human vertebral column is the provision of structural stability affording full mobility as well as protection of the spinal cord and axial neural tissues.1 While achieving these seemingly disparate objectives, the spine also contributes to the functional requirements of gait and to the maintenance of static weight-bearing postures (see Chap. 6).1

At the component level, the basic building block of the spine is the vertebra. The vertebra serves as the weight-bearing unit of the vertebral column, and it is well designed for this purpose. Although a solid structure would provide the vertebral body with sufficient strength, especially for static loads, it would prove too heavy and would not have the necessary flexibility for dynamic load bearing.2 Instead, the vertebral body is constructed with a strong outer layer of cortical bone and a hollow cavity, the latter of which is reinforced by vertical and horizontal struts called trabeculae.

The term vertebral column describes the entire set of vertebrae excluding the ribs, sternum, and pelvis (Fig. 22-1). The normal vertebral column is made up of 29 vertebrae (7 cervical, 12 thoracic, 5 lumbar, and 5 sacral) and four coccygeal segments. The adage that “function follows form” is very much applicable when studying the vertebral column. Although all vertebrae have similar characteristics, each has specific details that reflect its unique function (Table 22-1). The overall contour of the normal vertebral column in the coronal plane is straight. In contrast, the contour of the sagittal plane changes with development. At birth, a series of primary curves give a kyphotic posture to the whole spine. With development of the erect posture, secondary curves develop in the cervical and lumbar spines, producing a lordosis in these regions. The curves in the spinal column provide it with increased flexibility and shock-absorbing capabilities.2

A motion segment in the vertebral column is defined as two adjacent vertebrae and consists of three joints. One joint is formed between the two vertebral bodies and the intervertebral disk (IVD). The other two joints are formed by the articulation of the superior articular processes of the inferior vertebra and the inferior articular processes of the superior vertebra(Fig. 22-2). These latter joints are known as the facets or zygapophyseal joints.

The vertebral column contains 24 pairs of zygapophyseal joints, which are located posteriorly, and project from the neural arch of the vertebrae. The regional characteristics of the zygapophyseal joints are described in the relevant chapters. Mechanically, zygapophyseal joints are classified as plane joints as the articular surfaces are essentially flat.3 The articular surfaces are covered in hyaline cartilage and like most synovial joints, have small fatty or fibrous synovial meniscoid-like fringes that project between the joint surfaces from the margins.4 These intra-articular synovial folds act as space fillers during joint displacement and actively assist in the dispersal of synovial fluid within the joint cavity.1 The articular processes act as a mechanical barricade, particularly against excessive torsion and shear, permitting certain movements while blocking others3:

• Horizontal articular surfaces favor axial rotation.
• Vertical articular surfaces (in either sagittal or frontal planes) act to block axial rotation.

Most zygapophyseal joint surfaces are oriented somewhere between the horizontal and vertical planes. In the cervical spine, the zygapophyseal joints are relatively horizontal while progressively increasing toward 45 degrees to the horizontal from the upper to the lower segments.5–8 In the thoracic region, the joints assume an almost vertical direction while remaining essentially in a coronal orientation, which facilitates axial rotation and resists anterior displacement.9 In the lumbar spine, the zygapophyseal joints are vertical with a curved, J-shaped surface predominantly in the sagittal plane, which restricts rotation and also resists anterior shear.1 Understanding the variable structure and function of the human zygapophyseal joints and their relationship with the other components of the vertebral column is an important requirement in the examination and intervention of individuals with mechanical spinal pain disorders.1

The IVDs of the vertebral column lie between the adjacent superior and inferior surfaces of the vertebral bodies from C2 to S1 and are similar in shape to the bodies (Fig. 22-3). The IVD forms a symphysis or amphiarthrosis between two adjacent vertebrae and represents the largest avascular structure in the body.10 Each disk is composed of an inner nucleus pulposus (NP), an outer annulus fibrosus (AF), and limiting cartilage end plates. The annulus and end plates anchor the IVD to the vertebral body. The IVDs contribute 20–25% of the length of the vertebral column. In cervical and lumbar regions, the IVDs are thicker anteriorly and this contributes to the normal lordosis. In the thoracic region, each of the IVDs is of uniform thickness. Phylogenically, the IVD is a relatively new structure. In the human spinal column, the combined heights of the IVDs account for approximately 20–33% of the total length of the spinal column.11 The presence of an IVD not only permits motion of the segment in any direction up to the point that the disk itself is stretched, but also allows for a significant increase in the weight-bearing capabilities of the spine.12 A normally functioning disk is extremely important to permit the normal biomechanics of the spine to occur and to reduce the possibility of mechanical interference among any of the neural structures. Although the disk is incapable of independent motion, movement of the disk does occur during the clinically defined motions of flexion–extension, side bending, and axial rotation.13 The major stresses that must be withstood by the IVD are axial compression, shearing, bending, and twisting, either singly or in combination with each other.

The role of the IVD is unique because it operates as an osmotic system, holding neighboring vertebral bodies together, while simultaneously pushing them apart. As such, the IVD is a dynamic structure that responds to stresses applied from vertebral movement or from static loading.

There are regional differences within the spine, each with its own specific demands and function. As discussed, all vertebral disks have traditionally been described as being composed of three parts: the AF, the vertebral end plate, and a central gelatinous mass, called the NP (Fig. 22-1). However, this description is based on the anatomy of a lumbar disk, the region where most research has occurred and for which many authors have extrapolated the anatomy to all IVDs.14 An appreciation of the differing anatomy of the IVDs throughout the spine is important when developing clinical examination and intervention models.14

The spine contains four junctions, each of which is different in posterior element orientation and spinal curvature. Transitional vertebrae can occur at any of the junctions. The transition can be “complete” but is more commonly partial. These junctions, described by Schmorl and Junghanns15 as ontogenically restless, are often rich in anomalies16:

• The craniovertebral junction is located between the cervical spine and the atlas, axis, and head. This region is covered in Chapter 23.
• The cervicothoracic junction represents the region where the mobile cervical spine and the relatively stiffer superior segments of thoracic spine meet, and where the powerful muscles of the upper extremities and shoulder girdle insert. The cervicothoracic junction is described in Chapters 25 and 27.
• The thoracolumbar junction is located between the thoracic spine, with its large capacity for rotation, and the lumbar spine, with its limited rotation. This region is described in Chapter 27.
• The lumbosacral junction is located between the lumbar spine, with its ability to flex and extend, and the relative stiffness of the sacroiliac joints. This region is described in Chapters 28 and 29.

Although highly variable, the line of gravity acting on a standing person with ideal posture passes through the mastoid process of the temporal bone anterior to the second sacral vertebra, posterior to the hip, and anterior to the knee and ankle (see Chap. 6).3 In the vertebral column, the line of gravity is on the concave side of the apex of each region's curvature. As a consequence, ideal posture allows gravity to produce a torque that helps maintain the optimal shape of each spinal curvature.3

Spinal stability is characterized by the behavior of the spinal column and the coordination of muscles that surround the spine. There are two types of stability:

• Static. This type of stability refers to a state of equilibrium where the velocity of the object or body is zero. When a person is standing perfectly still with no swing back and forth, the person said to be in static equilibrium.
• Dynamic. This type of stability implies a change over time but the velocity is constant. Theoretically, if a perturbation is applied to the spine and the spine behaves as it did in its undisturbed state, it is said to be stable, whereas if the spine's kinematic behavior changes as a result of the disturbance, it is unstable.17 States requiring dynamic stability are far more common than those requiring static stability.

From the mechanical point of view, the spinal system is inherently unstable. Panjabi18,19 indicates that there are three subsystems that contribute to spinal stability:

• Passive system. The spinal column, which includes the vertebrae, IVDs, zygapophyseal joints, joint capsules, and ligaments (Fig. 22-4) are the load-bearing units and the source of passive stiffness for stabilizing the spine. Passive stiffness of the ligaments and joint capsules is mainly a factor at the extremes of range of motion (ROM). The effectiveness of the passive support system is a factor of the ability of its structures to resist the forces of translation, compression, and torsion.
• Active system. Muscles, which serve to reduce or prevent movement and are the source of active stiffness (i.e., muscles act like stiff springs) by using stored elastic energy and the level of activation or force.18,20 Because the passive stiffness is mainly engaged at the extremes of range, the primary source of stiffness for stability during movements in healthy individuals is from the active stiffness of the trunk muscles and not the passive stiffness from ligaments. A large number of muscles have a mechanical effect on the spine and pelvis and all muscles are required to maintain optimal control.20 Muscle activity must be coordinated to maintain control of the spine within a hierarchy of interdependent levels: control of intervertebral translation and rotation, control of spinal posture/orientation, and control of body with respect to the environment, in addition to maintaining a number of homeostatic functions such as respiration and continence.20–22 The concept of different trunk muscles playing differing roles in the provision of dynamic stability to the spine was proposed by Bergmark23 and later refined by others.24–29 The specific muscles that provide stability and their interactions are described in the relevant chapters.
• Central nervous system (CNS), which utilizes feedforward (anticipatory) control to generate active muscle stiffness and uses feedback (reflex) control to augment the stiffness.30 The CNS must continually interpret the status of stability, plan mechanisms to overcome predictable challenges, and rapidly initiate activity in response to unexpected challenges.20

The neutral zone is a term used by Panjabi18 to define a region of laxity around the neutral resting position of a spinal segment. The neutral zone is the position of the segment in which minimal loading is occurring in the passive structures (IVD, zygapophyseal joints, and ligaments) and the active structures (the muscles and tendons that control spinal motion), and within which spinal motion is produced with minimal internal resistance.2 Panjabi and colleagues31 have studied the effect of intersegmental muscle forces on the neutral zone and ROM of a lumbar functional spinal unit subjected to pure moments in flexion–extension, side bending, and rotation. Simulated muscle forces were applied to the spinous process of the mobile vertebra of a single motion segment using two equal and symmetric force vectors directed laterally, anteriorly, and inferiorly. The simulated muscle force maintained or decreased the motions of the lumbar segment for intact and injured specimens with the exception of the flexion ROM which increased.31

The interaction between the passive and active systems of the spine changes when there has been prolonged tension or cyclic loading of the passive system resulting in a change to the muscle responses in the form of a delayed response. Furthermore, it is hypothesized that these changes in muscle activation may lead to increased spinal compression forces, which have been recognized as a risk factor for vertebral end-plate fracture, especially if applied repetitively.35,36 An alternate consequence is that muscle insufficiency resulting from fatigue may shift the loading to the passive tissues,37,38 which may put the spine at increased risk of injury.

Under normal circumstances, when large perturbations are expected, preparatory coactivation of the spinal muscles enhances active stiffness, and reflexes augment the stiffness at the appropriate time.41 These anticipatory postural adjustments and corrective responses are part of a motor control strategy executed by the CNS that was learned from previous experience when performing similar movements or activities.42–45

The emphasis on spinal stability exercises should be to:

• Strengthen the trunk muscles so that they are able to produce sufficiently large forces and active stiffness. The timing and sequencing of muscle activity, coupled with the appropriate magnitude of muscle activation, produces smooth, accurate, and efficient movement behavior that is adjusted to the immediate demands and consequences within the environment.30
• Increase the endurance of the trunk muscles so that the force output of the muscles does not deteriorate.
• Incorporate sound motor learning principles to address impaired motor control strategies.

The various strategies to incorporate with the intervention for spinal instability are addressed in the appropriate chapters.

The movements of the vertebral column occur in diagonal patterns as a combination of flexion or extension with a coupled motion of side bending and rotation. Movements of the spine, like those elsewhere, are produced by the coordinated action of nerves and muscles. Agonistic and synergistic muscles initiate and perform the movements, whereas the antagonistic muscles control and modify the movements. The amount of motion available at each region of the spine is a factor of a number of variables. These include

• disk-vertebral height ratio
• compliance of the fibrocartilage
• dimensions and shape of the adjacent vertebral end plates
• age
• disease
• gender

The type of motion available is governed by

• the shape and orientation of the articulations
• the ligaments and muscles of the segment, and the size and location of its articulating processes

Including translations and rotations around three different axes, the spine is considered to possess 6 degrees of freedom.46 Although the ROM at each vertebral segment varies, the relative amounts of motion that occur at each region is well documented11,47:

• In the upper craniovertebral region (occiput to C2), there is comparatively little flexion–extension, whereas the mid to lower cervical spine permits increasing flexion–extension movements from approximately 10 degrees at the C2–3 level to about 20 degrees at C5–6 and C6–7. Axial rotation in the upper cervical spine is 30–40 degrees in each direction, whereas it is 5–6 degrees in the lower cervical spine.
• Flexion–extension movements (see Fig. 22-3) are about 4 degrees in the upper thoracic spine, 6 degrees in the midthoracic spine, and 12 degrees in the lower thoracic spine. Side bending in the upper thoracic spine is approximately 6 degrees. Axial rotation in the upper thoracic spine is 5–6 degrees.
• In the lumbar spine, there is a gradual increase of flexion–extension movements from about 12 degrees at L1–L2 to 20 degrees at the L5–S1 level. Side bending in the lumbar spine is greatest at L3–L4 where it is approximately 8–9 degrees. Axial rotation in the lumbar spine is minimal.
• Although various motion patterns have been proposed for the sacroiliac joint,48–51 the precise model for sacroiliac motion has remained fairly elusive (see Chap. 29).52–54 Postmortem analysis has shown that until an advanced age, small movements are measurable under different load conditions.55,56

In general, the human zygapophyseal joints of the spine are capable of only two major motions: gliding upward and gliding downward. If these movements occur in the same direction, flexion or extension occurs. If the movements occur in opposite directions, side bending occurs. Although rotation does occur as a motion component within intervertebral segments, it is always coupled and never an isolated motion.57 Indeed during functional rotation of the spine, the actual motion occurring at any given zygapophyseal joint is a linear glide. Because the orientation of the articular facets of the zygapophyseal joints do not correspond exactly to pure planes of motion, pure motions of the spine occur very infrequently.46 In fact, most motions of the spine occur three-dimensionally because of the phenomenon of coupling. Coupling involves two or more individual motions occurring simultaneously at the segment and has been found to occur throughout the lumbar,58 thoracic,59 and cervical regions.60 Descriptions about the types of coupling that occurs in these regions are provided in the respective chapters. All normal motion in the cervical, thoracic, and lumbar regions involves both sides of the segment moving simultaneously around the same axis. That is to say, a motion of the right side of a segment produces an equal motion on the left side of that same segment. If both sides of a vertebral segment are equally impaired (equally hypomobile or hypermobile), there is no change in the axis of motion except in the case where it ceases to exist, as in a bony ankylosis. Where a symmetric motion impairment exists, there is no noticeable deviation from the path of flexion or extension (impaired side bending and rotation), but rather, the path is shortened with a hypomobility (producing decreased motion) or lengthened with a hypermobility (producing increased motion).

An alteration to the structures of the motion segment can result in a loss of motion, a loss of segment integrity (instability), or a loss of function. These changes result mainly from injury, developmental changes, fusion, fracture healing, healed infection, or surgical arthrodesis.47 The loss of motion segment integrity, which can be measured with flexion–extension roentgenograms, is defined as an anteroposterior motion of one vertebra over another that is greater than 3.5 mm in the cervical spine, greater than 2.5 mm in the thoracic spine, and greater than 4.5 mm in the lumbar spine.61 Loss of motion segment integrity also may be defined as a difference in the angular motion of two adjacent motion segments greater than

• 11 degrees in the cervical spine
• 15 degrees at L1–L2, L2–L3, and L3–L4
• 20 degrees at L4–L5
• 25 degrees between L5 and S1

Fryette's Laws of Physiologic Spinal Motion62

Although listed as laws, Fryette's descriptions of spinal motion are better viewed as concepts because they have undergone review and modifications over time. These concepts serve as useful guidelines in the evaluation and intervention of spinal dysfunction and are cited throughout many texts describing spinal biomechanics.

Fryette's First Law

“When any part of the lumbar or thoracic spine is in neutral position, side bending of a vertebra will be opposite to the side of the rotation of that vertebra.”

The term neutral, according to Fryette, is interpreted as any position in which the zygapophyseal joints are not engaged in any surface contact, and the position where the ligaments and capsules of the segment are not under tension. This law describes the coupling for the thoracic and lumbar spines. The cervical spine is not included in this law because the zygapophyseal joints of this region are always engaged. When a lumbar or thoracic vertebra is side bent from its neutral position, the vertebral body will turn toward the convexity that is being formed, with the maximum rotation occurring near the apex of the curve formed.

Dysfunctions that occur in the neutral range are termed by osteopaths as type I dysfunctions.

Fryette's Second Law

“When any part of the spine is in a position of hyperextension or hyperflexion, the side bending of the vertebra will be to the same side as the rotation of that vertebra.”

Put simply, when the segment is under load, the coupling of side bending and rotation occurs to the same side. The term non-neutral, according to Fryette, is interpreted as any position in which the zygapophyseal joints are engaged in surface contact, the position where the ligaments and capsules of the segment are under tension, or in positions of flexion or extension. This law describes the coupling that occurs in the C2–T3 areas of the spine.

Dysfunctions occurring in the flexion or extension ranges are termed by osteopaths as type II dysfunctions.

Fryette's Third Law

Fryette's third law tells us that if motion in one plane is introduced to the spine, any motion occurring in another direction is thereby restricted.

Combined Motions

It would appear that, irrespective of the coupling that occurs, there is a great deal of similarity between a motion involving flexion followed by left side bending, and a motion involving left side bending followed by flexion. However, although both motions have the same end result, they use different methods to arrive there. The same could be said of the following combined motions:

• Flexion and right side bending followed by right side bending and flexion.
• Extension and right side bending followed by right side bending and extension.
• Extension and left side bending followed by left side bending and extension.

By using combined motions, the clinician can often reproduce a patient's symptom that was not reproduced using the planar motions of flexion, extension, side bending, and rotation.64–66 However, care should be taken when utilizing combined motions, especially with the acute and subacute patient, when a reduction of symptoms through modalities and gentle exercise might be preferable to exacerbating the patient's condition through a comprehensive movement examination.

Using a biomechanical model, a restriction of extension, side bending, and rotation to the same side of the pain is termed a closing restriction, whereas a restriction of the opposite motions (flexion, side bending, and rotation to the opposite side of the pain) is termed an opening restriction. Motions that involve flexion and side bending away from the symptoms tend to invoke a stretch to the structures on the side of the symptoms, whereas motions that involve extension and side bending toward the side of the symptoms produce a compression of the structures on the side of the symptoms.64–66 An example of a stretching pattern would be pain on the right side of the spine that is increased with either flexion followed by a left side-bending movement or a left side-bending motion followed by a flexion movement. A compression pattern would involve pain on the right side of the spine that is increased with a movement involving either extension followed by right side bending or right side bending followed by extension.

The symptom reproduction that occurs with combined motions usually follows a logical and predictable pattern. However, there are situations in which illogical patterns are found. Because the vertebral column consists of many articulating segments, movements are complex and usually involve several segments resulting in restrictions that may be complex and apparently illogical. An example of such a pattern would be pain on the right side of the spine that is increased with a flexion and right side bending combination but decreased with an extension and right side bending combination. The movements just described involve a combination of stretching and compression movements. These illogical patterns typically indicate that more than one structure is involved.64–66 Of course, they could also indicate to the clinician that the patient does not have a musculoskeletal impairment.

The examination of the spine is complicated by the number of conditions that can cause pain in this region of the body. In addition, there is little scientific evidence for the establishment of many of the diagnostic labels attributed to spinal pain, such as instability, degenerative disc disease, and subluxation.67

The purpose of the examination is to correctly identify those patients who will benefit from a physical therapy intervention. The correct identification of a diagnosis requires the use of evidence-based measuring tools that are valid, specific, and sensitive. There are numerous methods for examining and evaluating the spine, and each results in a conclusion that determines the course of the intervention.68,69 Unfortunately, many of the procedures that are used today to examine the spine demonstrate methodologic shortcomings.67–69 The interventions for spinal conditions fair no better. Despite the ever-increasing numbers of randomized controlled trials evaluating interventions for low back pain (LBP),70 treatment outcomes remain less than optimal.71 One reason for this may be the fact that many trials test interventions in a heterogeneous population of patients with LBP and such a diverse group of patients may not correspond to the one treatment approach.72 This hypothesis has led to the design of classification systems to identify subgroups of patients who may respond preferentially to certain treatments.73

Use of Traditional Classification Systems

In recent years, attempts have been made to use a variety of methods to classify spinal pain, particularly LBP, into syndromes. The term syndrome implies that the specific diagnosis is unknown. A syndrome is a collection of signs and symptoms that, collectively, characterizes a particular condition. In the spine, where determining a specific diagnosis has historically been proven to be extremely difficult, syndromes have become popular By classifying syndromes, it is proposed that a patient is more likely to respond to a type of intervention unique to that syndrome. The criteria that have thus been used to categorize a syndrome include the following:

• Pathoanatomy.74,75 This strategy involves using correlations to produce categories. The disadvantage of using pathoanatomy is the difficulty in identifying a relevant pathoanatomic cause for most patients.76
• Presence or absence of radiculopathy.77,78
• Location and type of pain.79
• Duration of the symptoms (acute, subacute, or chronic).80
• Activity and work status.78,81
• Impairments identified during the physical examination.
• Direction of motion that reproduces, peripheralizes, or centralizes the symptoms.82,83

The more common classifications are outlined next. The use of such classification systems may have some prognostic value and can direct clinicians to specific interventions.84

Osteopathic System

Osteopaths rely on the results from the active motion tests and position tests to determine their intervention approach. Note: Osteopaths use the term side flexion instead of side bending.

Position Testing

Position testing involves palpation of the soft tissues over paired transverse processes of the spine, to detect palpable positional irregularity and altered tissue tension at a segmental level when the spine is positioned in flexion or extension compared with neutral. To locate the transverse process in the lumbar spine, the clinician first locates the spinous process to determine the level and then moves slightly laterally and superiorly by placing the thumbs on either side of the spinous process. Thus, the clinician must be very familiar with so-called layer palpation to be sure that the palpating fingers are monitoring the positions of the transverse processes at a particular segmental level. Vertebral dysfunctions occur as a combination of movements in the three planes. The key movement is rotation. Theoretically, the rotational dysfunction, which is a result of the altered axis of rotation produced by the stiffer of the two sides of the segment, will be palpated as a much firmer end-feel to the palpation on that side. The direction of the rotation is named after the more posterior of the two transverse processes, and the positional name is an osteokinematic one having no established relationship with any joint.

Position Testing in Extension

If a marked segmental rotation is evident at the limit of extension, this would indicate that one of the facets is unable to complete its inferior motion (i.e., it is being held in a relatively flexed or superior position). The direction of the resulting rotation (denoted in terms of the anterior part of the vertebral body) informs the clinician as to which of the facets is not moving. For example, if the segment is rotated to the left when palpated in extension, the right zygapophyseal joint is not moving normally. This impairment can be described in one of the three ways as follows:

1. The right zygapophyseal joint cannot extend or “close.”

2. The right zygapophyseal joint is flexed (F), rotated (R), and side-flexed (S) left (L) around the axis of the right zygapophyseal joint.

3. The right zygapophyseal joint is unable to perform any motions that require an inferior glide, such as extension, right side bending, and right rotation.

FRS or extension impairments are more evident in the positional tests than ERS impairments (described next) because there is less overall motion available into extension.

Position Testing in Flexion

If a marked segmental rotation is evident in full flexion, this indicates that one of the facets cannot complete its superior motion. For example, if the segment is found to be left-rotated when palpated in flexion, the left zygapophyseal joint is not moving normally.

This impairment can be described in one of the three ways as follows:

1. The left zygapophyseal joint cannot flex or “open.”

2. The left zygapophyseal joint is extended (E), rotated (R), and side-flexed (S) left (L).

3. The left zygapophyseal joint is unable to perform any motion that requires a superior glide such as flexion, right rotation, and right side bending.

Position Testing in Neutral

Positional testing is performed in the neutral spine position for three reasons as follows:

1. If a rotational impairment of a segment exists only in neutral and is not evident in either full flexion or full extension, the cause of the impairment is probably not mechanical in origin but rather neuromuscular. These neuromuscular impairments are usually found at the spinal junctions, particularly the thoracolumbar and cervicothoracic junctions.

2. If a marked rotation is evident at a segment and this rotation is consistent throughout flexion, extension, and neutral, then the cause is probably an anatomic anomaly (e.g., scoliosis) rather than an articular problem.

3. If the cause of the rotational impairment is articular (zygapophyseal joint), the positional testing in neutral gives the clinician an idea as to the starting position of the corrective technique.

The terminology used to describe the rotational disruption of the pure spinal motions (ERS or FRS) describes the positional and kinetic impairments only. It does not indicate what the pathology might be. Reasons for these impairments, other than movement dysfunctions, may include bony anomalies such as a deformed transverse process, compensatory adaptation, structural scoliosis, or a hemivertebra.

The analysis of the change in the rotational impairment between full flexion and full extension theoretically gives clues as to the pathology. Thus, in conjunction with other tests, such as active motion testing, this analysis can assist in ascertaining a biomechanical diagnosis.

Position testing has been found to be very reliable when used by experienced clinicians to identify segmental levels based on the relative position of spinous processes.85 The results for inter-rater reliability have been mixed when clinicians are asked to determine lumbar segmental abnormality using position testing,86,87 and poor when attempting to determine the segmental level of a marked spinous process.88

McKenzie System82,83

The McKenzie mechanical diagnostic and classification approach is a noninvasive and an inexpensive method of assessing patients with cervical and LBP that uses physical signs, symptom behavior, and their relation to end range test movements to determine appropriate classification and intervention.

The McKenzie approach focuses on the following three components.

• Providing a mechanical diagnosis.
• Providing a mechanical treatment, based on the mechanical diagnosis.
• Prevention of recurrence which is achieved by
  • emphasizing the patient's responsibility for their own recovery
  • fully exploring the patient's self generated forces before progression to externally applied forces.

According to McKenzie, symptoms of lumbar and/or cervical pathology can demonstrate a phenomenon of centralization and peripheralization.82,89,90

• Centralization of symptoms is the immediate or eventual abolition of the most distal extent of referred or radicular pain toward the midline of the spine in response to therapeutic loading strategies. Centralization occurs more commonly with extension, especially with end range repeated movements. Although centralization of the symptoms can be associated with an increase in spinal pain, it normally indicates improvement in the patient's condition and provides the clinician with a directional preference.
• Peripheralization of symptoms indicates movement in the opposite direction and is usually associated with a poorer prognosis.

The history taking is an integral component of the McKenzie approach. The purpose of the history is to provide the clinician with information regarding

• an overall impression of the clinical presentation
• the site of pain
• the stage of the disorder
• the status of the presenting condition. The severity of problem is used to guide the vigor of the examination
• the identification of red flags
• the baseline of symptomatic/mechanical presentation against which improvements can be judged
• any aggravating/relieving factors (especially the role of posture). This helps the clinician to develop a hypothetical diagnosis by syndrome
• functional limits on the patient's quality of life

During the initial observation, the patient's sitting and standing postures are noted to reveal how the spine is habitually subjected to static loading by the patient. In addition, the patient is asked to perform a single movement of each movement plane direction (see below) while the clinician notes the quantity and quality of movement—the ability of the patient to achieve end range with spinal curve reversal and without deviating from the intended movement plane.91 The accurate assessment of the effect of repeated movements/sustained positions on the patient's pain patterns is a key component of the McKenzie examination (Table 22-2). The movement plane directions evaluated for both the cervical and lumbar spines are those within which the clinically presenting antalgic postures occur.91

• Cervical spine. The movements observed include protrusion, flexion, retraction, extension, side bending right, side bending left, rotation right, and rotation left.
• Lumbar spine. The movements observed include flexion, extension, side gliding right, side gliding left.

  After the quantity and quality of movement is assessed by the performance of single movements in each movement plane direction, dynamic and static tests are performed.91 The effects of loading in a certain movement plane direction are highlighted best by repetition (dynamic) or sustained (static) loading. Static loading tests are generally used when dynamic tests do not provide a clear preferred loading strategy. With both the static and dynamic tests, loading in a sagittal movement plane direction is typically explored first, unless the patient has significant antalgia in a coronal movement plane direction, in which case, the coronal movement plane is explored first.91 Should loading in the coronal plane not provide satisfactory answers, the transverse movement plane is explored.

• Dynamic tests. These tests involve performing a single motion within the movement plane direction being studied, followed by repetitive motion in the same movement plane direction while the clinician closely monitors how mechanics and symptoms respond during motion, at end range, and after the dynamic loading. The testing progression applied includes the following91:
  • Cervical spine: flexion in sitting, retraction in sitting, retraction-then-extension in sitting, retraction in lying, and retraction extension in lying. If required, the following tests are also performed: protrusion in sitting, retracted side bending right in sitting, retracted side bending left in sitting, retracted rotation right in sitting, and retracted rotation left in sitting.
  • Lumbar spine: flexion in standing, extension in standing, flexion in lying, and extension in lying. If required, the following tests are also performed: side gliding right in standing or prone extension with right lateral shift and side gliding left in standing or prone extension with left lateral shift.
• Static tests. These tests are often used as ancillary tests to confirm dynamic testing or to further explore the effects of loading when dynamic testing yields no definitive conclusion.91
  • Cervical spine: protrusion, flexion, retraction (sitting or supine), retraction and extension (sitting, prone, or supine), retracted side bending right or left, and retracted rotation right or left.
  • Lumbar spine: sitting slouched, sitting erect, standing slouched, standing erect, lying prone in extension, long sitting, lateral shift right or left, and rotation in flexion.

The clinical reasoning intrinsic to the McKenzie method classifies mechanical and symptomatic responses to loading into three main syndromes: postural, dysfunction, and derangement (Table 22-3) and (Fig. 22-4).

The posture syndrome is proposed to result from sustained loading of the tissues during end range positions/postures. The pain associated with the postural syndrome is of a gradual onset, dull, local, midline, symmetric, and never referred. Prolonged postures worsen the pain, whereas movement abolishes it. On examination, the patient demonstrates no spinal deformity or loss of range and repeated movements do not produce the symptoms. The onset of symptoms, which is time-dependent (usually occurring after more than 15 minutes), is provoked with sustained end-of-range positions.

The dysfunction syndrome is proposed to result from an adaptive shortening of some soft tissues and an overstretching of others. The intermittent pain associated with this syndrome is local, adjacent to the midline of the spine, and not referred. The exception occurs in the case of an adherent nerve root (ANR) where the pain may be felt in the buttock, thigh, or calf (Table 22-4). The ANR represents the only time when distal pain is experienced in the dysfunction syndrome, and the only time when distal symptoms are repeatedly reproduced as part of its management. Activities and positions at the end of range worsen the pain of the dysfunction syndrome, whereas activities that avoid end ranges lessen the symptoms. On examination, the patient demonstrates a loss of motion or function that distinguishes this syndrome from the posture syndrome. Repeated movements do not alter the symptoms and the loss of motion, or function, may be symmetric or asymmetric.

The derangement syndrome is thought to result from a displacement or an alteration in the position of joint structures. The joint structure most commonly involved is the IVD, and McKenzie divides these disturbances into posterior disk and anterior disk derangements. The posterior derangements are further subdivided into seven derangement categories. Derangements 1 through 6 describe posterior derangements, whereas derangement 7 describes the anterior derangement (Table 22-5).

The pain of a derangement syndrome, which is usually of a sudden onset and associated with paresthesia or numbness, is dull or sharp and can be central, unilateral, symmetric, or asymmetric. Although the pain may be referred into the buttock, thigh, leg, or foot, it varies in both intensity and distribution. Bending, sitting, or sustaining positions worsen a posterior derangement, whereas walking and standing worsen an anterior derangement. Patients with a posterior derangement often feel better when walking and lying, whereas patients with an anterior derangement usually feel better in sitting and other flexed positions. On examination, a lateral shift may be noted. There is always a loss of motion and function. Certain motions produce, increase, or cause the symptoms to peripheralize (move away from the spine), whereas other motions decrease, abolish, or centralize the symptoms. McKenzie advocates a variety of loading principles for the reduction of the derangement.

• Extension
• Flexion
• Lateral movement
• Force progression
  • Start position: loaded versus unloaded
  • Positioning to mid range
  • Positioning at end range
• Dynamic patient-generated forces
  • Patient motion to mid range
  • Patient motion to end range
  • Patient motion to extreme ranges using patient over-pressure (sag).
• Clinical generated forces
  • Patient motion to mid range with clinician's overpressure
  • Patient motion to end range with clinician's overpressure
  • Clinician mobilization
  • Clinician high-velocity thrust technique
• Force alternatives
  • Static patient-generated forces
  • Strategy: sagittal/frontal/or combination
  • Time factor: sustained/repeated
  • Frontal plane angle during combined procedures

Once the subjective history and mechanical evaluation has been performed on the initial visit, the clinician should have an idea regarding which mechanical category the patient may belong. Depending upon the syndrome, a specific self-treatment program is prescribed for home use, and patients are encouraged to accept responsibility for their intervention and recovery. The specific programs relative to the cervical and lumbar spine are described in the respective chapters.

The inter-rater reliability of the McKenzie method in performing clinical tests and classifying patients with LBP into syndromes has been investigated in a number of studies.68,89,92–99

Repeated movements have been found to be a reliable part of the examination of the spine in a number of studies.98,100

In one study,98 intertester reliability between two therapists trained in the McKenzie method seemed to be high for classifying patients with LBP into McKenzie syndromes, and excellent for judging pain status change, including the centralization phenomenon, during examination of the lumbar spine.96,98 The results from a study by Kilpikoski also suggested that intertester reliability in performing clinical tests and classifying patients with LBP into the main McKenzie syndromes is high when the clinicians have been trained in the McKenzie method.99

Donahue and colleagues92 suggested that the McKenzie method was unreliable for detecting the presence of a lateral shift, but that a relevant lateral component could be reliably detected using symptom response to repeated movements. In contrast, Tenhula and associates95 noted a significant relation between positive results on a contralateral side-bending movement test and a lumbar lateral shift, indicating that the former is a useful clinical test for confirming the presence of a lateral shift in patients with LBP.

Kilby and colleagues97 found the “McKenzie algorithm” (Fig. 22-5) to be reliable in the examination of pain behavior and pain response with repeated movements but unreliable in the detection of end range pain and lateral shift.

Riddle and Rothstein68 found that the McKenzie approach was unreliable when physical therapists classified patients into McKenzie syndromes. They suggested that a potential source of unreliability was in determining whether the patient had a lateral shift and, if so, in which direction and whether the patient's pain centralized or peripheralized during test movements.68

Treatment-Based Classification System

This system, originally proposed by Delitto and colleagues,101 uses information gathered from the physical examination and from the patient's self-reports of pain (pain scale and pain diagram) and disability (modified Oswestry questionnaire) to classify the patient with LBP.101,102 The classification determines whether the patient's condition is amenable to physical therapy or whether care from another practitioner is required. The treatment-based classification (TBC) system is designed for patients judged to be in the acute stage, with the determination of acuity based on the alignment of various body structures, the effect of movements on symptoms, the nature of the patient's symptoms, the degree of disability, and the goals for management, instead of strictly on the elapsed time from injury.102

Patients in the acute stage are those with higher levels of disability (modified Oswestry scores generally greater than 30), who report substantial difficulty with basic daily activities such as sitting, standing, and walking. Intervention goals are to improve the ability to perform basic daily activities, reduce disability, and permit the patient to advance in his or her rehabilitation.102 Patients judged to be in the acute stage are assigned to a classification that guides the initial intervention. Seven classifications are described for patients in the acute stage101:

1. Immobilization.

2. Lumbar mobilization.

3. Sacroiliac mobilization.

4. Extension syndrome.

5. Flexion syndrome.

6. Lateral shift.

7. Traction.

Each of the classifications has key examination findings and recommended interventions. To facilitate comparisons among classifications, these seven classifications may be collapsed further into four classifications based on similarities in the prescribed interventions.

1. Mobilization/manipulation.

2. Stabilization (either sacroiliac or lumbar).

3. Specific exercise (flexion, extension, or lateral shift correction).

4. Traction.

Mobilization/Manipulation

The mobilization classification includes patients believed to have indications for either sacroiliac or lumbar region mobilization or manipulation. Mobilization of the sacroiliac region is indicated by asymmetries of the pelvic landmarks (anterior superior iliac spines, posterior superior iliac spines, and iliac crests) with the patient in the standing position and by positive results in three of four tests as follows:

1. Asymmetry of posterior superior iliac spine heights with the patient sitting.

2. The standing flexion test.

3. The prone-knee flexion test.

4. The supine to long-sitting test.

Acute-stage intervention for this category involves a manipulation technique proposed to affect the sacroiliac joint region, muscle energy techniques, and ROM exercises for the lumbosacral spine.96

Lumbar mobilization is believed to be indicated by the presence of the following:

• Unilateral paraspinal pain in the lumbar region.
• Asymmetric amounts of lumbar side-bending ROM with the patient standing in either an “opening” pattern (limited and painful flexion and side-bending ROM to the side opposite the pain) or a “closing” pattern (limited and painful extension and side-bending ROM to the same side as the pain).

The intervention for this category consists of lumbar mobilization or manipulation techniques and ROM exercises for the lumbosacral spine.

Stabilization

The stabilization classification is purported to identify patients with lumbar segmental instability. Key examination findings are typically gleaned from the history and include a history of frequent episodes of symptoms precipitated by minimal perturbations, frequent use of manipulation with short-term relief of symptoms, trauma, or reduced symptoms with the prior use of a corset.101

The intervention for this category focuses on strengthening exercises for the back extensor and abdominal exercises as well as stabilization exercises designed to improve dynamic control of the lumbar spine.102

Specific Exercise

The key examination finding that places patients into a specific exercise classification is the presence of centralization with movement of the lumbar spine based on the McKenzie method.82 When either lumbar flexion or extension is found to produce centralization, the patient is treated with specific exercises in the direction producing the centralization. Patients are also educated to avoid positions found to peripheralize symptoms during examination.

The primary examination findings that lead to a classification of a lateral shift, in which the shoulders are offset from the pelvis in the frontal plane, are a visible frontal plane deformity and asymmetric side-bending ROM in standing. If correction of the deformity produces centralization, the patient is taught specific exercises designed to correct the lateral shift (i.e., pelvic translocation).82

Traction

The traction classification is reserved for patients with signs and symptoms of nerve root compression who are unable to centralize with any lumbar movements. The acute stage intervention involves the use of mechanical traction or autotraction103 in an attempt to produce centralization.

Under the TBC, patients judged to be in a more chronic stage are treated with a conditioning program designed to improve strength, flexibility, and conditioning, or with a work-reconditioning program.101

A recent cross-sectional study73 to evaluate the TBC algorithm found that approximately one-half of patients with acute or subacute LBP met the criteria for only one treatment subgroup. In addition, although approximately 25% of the patients met the criteria for more than one subgroup, 25% of the patient's did not meet the criteria for any of the treatment subgroups. This latter finding suggests that further research is needed to refine the algorithm.

Canadian Biomechanical Model104

The Canadian model is an eclectic approach founded upon an amalgam of doctrines and techniques that incorporate the biomechanical concepts of the Norwegians,105–108 the selective tissue tension principles of Cyriax,79,109 the muscle energy concepts of the American osteopaths,110–112 the combined movement testing of Edwards,68 the manipulative techniques of Stoddard,113 the various approaches to stabilization therapy,25,114–116 the exercise protocols of McKenzie,82,83 the muscle balancing concepts of Janda, Jull, and Sahrmann,117–119 and the movement reeducation principles of the neurodevelopment and sensory integrationist clinicians.120,121

The basic tenet of the Canadian approach is that, given an understanding of the anatomy and biomechanics of a joint, segment or region, the pathologic mechanisms can be extrapolated using a series of testing procedures. These tests include the Cyriax upper and lower quarter scanning examinations for differential diagnosis (see Chap. 4), uncombined (plane) and combined movement testing, passive physiological intervertebral motion (PPIVM) tests, passive accessory intervertebral motion (PAIVM) tests, and segmental stability tests.

Following the active motion tests, the clinician should be able to determine the planar motions (flexion, extension, and side bending and rotation to both sides) that provoke symptoms. However, the clinician cannot yet determine whether a joint or soft tissue is responsible for the pain. Two tests are used to help determine the presence of articular involvement: the PPIVM tests and the PAIVM tests.

Passive Physiologic Intervertebral Mobility Testing

The PPIVM tests are used to determine the amount of segmental mobility available in the spine. The PPIVM tests assess the ability of each segment to move through its normal ROM. The adjacent spinous processes of the segment are palpated simultaneously and movement between them is assessed as the segment is passively taken through its physiologic range. If both spinous processes move simultaneously, there is no movement occurring at the segment and a hypomobility exists. If the movement between adjacent spinous processes appears excessive when compared with the level above or below, a hypermobility or instability may be suspected.

Thus, once the physiologic range has been assessed, it can be categorized as either normal, excessive, or reduced compared with the neighboring segment. Other positive findings for a hypomobility would be a reduced range in a capsular or noncapsular pattern in the active motion tests, a reduced joint glide, and a change in the end-feel from the expected norm for that joint. The end-feel and joint glide are both tested in the PAIVM tests (discussed next).

Therefore, one of three conclusions may be drawn from the PPIVM tests:

1. The joint motion is determined to be normal. If the PPIVM test of a spinal joint has a normal range and end-feel, the joint can usually be considered normal because in the spine, instability will invariably produce a hypermobility. However, in a peripheral joint, it is possible to have a normal range in the presence of articular instability. Thus, if a peripheral joint demonstrates a normal physiologic range, the stability of the joint needs to be tested using the segmental stability tests (see later discussion) before the clinician can deem the joint to be normal.

2. The joint motion is determined to be reduced (hypomobile). A hypomobility can be painful, suggesting an acute sprain of a structure, or painless, suggesting a contracture or an adhesion of the tested structure. If the motion is determined as being reduced (hypomobile), PAIVM testing is performed to determine, using the joint glides, whether the reduced motion is a result of an articular or extra-articular restriction.

3. The motion is determined to be excessive (hypermobile). If the motion is determined to be excessive, segmental stability tests are performed to determine whether a hypermobility or an instability is present (see later discussion).

It is worth noting that the judgments of joint stiffness made by experienced physical therapists examining patients in their own clinics have been found to have poor reliability in a number of studies. In two separate studies, 100,122 manual therapy tests that provoke patient's symptoms were found to be more reliable than judging stiffness in the spine. Smedmark and colleagues123 investigated the interexaminer reliability of passive intervertebral motion testing. In their study, passive intervertebral motion of the cervical spine was assessed independently by two physical therapists whose backgrounds (education and clinical experience) were equal. Sixty-one patients seeking care for cervical problems at a private clinic were included in the study, in which three segments of the cervical spine and the mobility of the first rib were graded as stiff or not stiff. Data analyzed by percentage agreement and κ coefficient indicated an interexaminer reliability that was greater than expected by chance. Results demonstrated interexaminer reliability of between 70 and 87% and κ coefficients ranging between 0.28 and 0.43, considered to be only fair to moderate.

However, in a study by Gonnella and colleagues124 the performance of five physical therapists in evaluating passive mobility of the vertebral column of five asymptomatic endomorphic subjects was assessed for the reliability within and between therapists, the criteria for grading, and the subjects themselves. Intratester reliability was found to be reasonable to good; there was no intertester reliability. Reliability was highest at L1–L3 and lowest at L5–S1. Problems identified were idiosyncratic behaviors that may develop with experience, subject characteristics, and the instrument itself.

Passive Accessory Intervertebral Mobility Testing

In the PAIVM tests, the clinician assesses the joint glides or accessory motions of each joint and determines the type of end-feel encountered.

Accessory motions are involuntary motions. With few exceptions, muscles cannot restrict the glides of a joint, especially if the glides are tested in the loose-pack position of a peripheral joint and at the end of available range in the spinal joints.125 Thus, if the joint glide is restricted, the cause is an articular restriction such as the joint surface or capsule. If the glide is normal, then the restriction must be from an extra-articular source such as a periarticular structure or muscle.

Determining the type of end-feel is very important, particularly in joints that only have very small amounts of normal range such as those of the spine. To execute the end-feel, the point at which resistance is encountered is evaluated for quality and tenderness. Additional forces are needed as the end range of a joint is reached and the elastic limits are challenged. This space, termed as the end-play zone, requires a force of over-pressure to be reached and when that force is released, the joint springs back from its elastic limits. Because pain generally does not limit movement in specific and deliberate passive tests, the PAIVM tests are better for gauging the reliability of the limitation based on tissue resistance, rather than patient willingness, and are better at determining the pattern of restriction than the active tests. If pain is reproduced with end-feel testing, it is useful to associate the pain with the onset of tissue resistance to gain an appreciation of the acuteness of the problem. A normal end-feel indicates normal range, whereas an abnormal end-feel suggests abnormal range, either hypomobile or hypermobile. If the articular restraints are irritable, the range will be about normal but will be accompanied by a spasm end-feel because a reflex muscle contraction can prevent the motion into an abnormal and painful range.125,126 If nonirritable, the physiologic range will be increased and the end-feel will be softer than the expected capsular one, suggesting a compromise of the structure under examination. A hard, capsular end-feel indicates a pericapsular hypomobility, whereas a jammed end-feel indicates a pathomechanical hypomobility.

The PAIVM tests can be performed symmetrically or asymmetrically. These tests are described in the relevant chapters of this text. Generally speaking, the symmetric tests are used when planar motions have produced pain in the active motion tests, whereas the asymmetric techniques are used when the combined motions have produced pain in the active motion tests.

Caution must be taken when basing clinical judgments on the results of accessory motion testing alone because few studies have examined the validity and reliability of accessory motion testing of the spine or extremities and little is known about the validity of these tests for most inferences.127

Hayes and Peterson128 examined two physical therapists who used standardized positions to evaluate two knee motions and five shoulder motions. Evaluators did not interview subjects and were blinded to previous test results. Evaluators applied overpressure and noted the end-feel while subjects identified the moment their pain was reproduced. Following testing, subjects rated their pain intensity. Analyses included percentage of agreement κ, weighted κ, and maximum κ coefficients and confidence intervals. Analyses were repeated for subjects whose pain intensity during testing did not change between examinations. Intrarater κ coefficients varied from 0.65 to 1.00 for end-feel, and intrarater weighted κ coefficients varied from 0.59 to 0.87 for pain-resistance sequence. Most coefficients remained stable or improved for the unchanged subjects. Inter-rater κ coefficients for end-feel and weighted κ coefficients for pain resistance sequence varied from −0.01 to 0.70. The authors concluded that the reliability of end-feel and pain-resistance judgments at the knee and shoulder was generally good, especially after accounting for subject change and unbalanced distributions. Inter-rater reliability, however, was generally not acceptable, even after accounting for these factors.128

In a separate study by the same authors,129 the relationship between pain and normal and abnormal (pathologic) end-feels during passive physiologic motion assessment at the knee and shoulder were examined. Physical therapists examined subjects with unilateral knee or shoulder pain, and each subject was examined twice. Passive physiologic motions, two at the knee and five at the shoulder, were tested by applying an overpressure at the end of ROM, using standardized positions. Subjects reported the amount of pain (0–10) immediately after the evaluator recorded the end-feel. The authors concluded that abnormal (pathologic) end-feels are associated with more pain than normal end-feels during passive physiologic motion testing at the knee or shoulder. Dysfunction should be suspected when abnormal (pathologic) end-feels are present.129

Based on review of the literature of the MEDLINE and CINAHL databases for the period of 1980 through 2000, using the keywords motion palpation, accessory motion, and intervertebral motion, Huijbregts130 performed a review of 28 reliability studies. The following conclusions were made from this study:

• Intra-rater agreement varied from less than chance to generally moderate or substantial agreement.
• Inter-rater agreement only rarely exceeded poor to fair agreement.
• Rating scales measuring absence versus presence or magnitude of pain response yielded higher agreement values than mobility rating scales.

Segmental Stability Tests

These are tests for movements that should not exist to an appreciable degree. The tests include maneuvers that induce non-physiologic rotational, anterior, posterior, and transverse shears to the segment. The limitation in the clinical diagnosis of segmental instability lies in the difficulty of accurately detecting excessive intersegmental motion, because even conventional radiologic testing is often insensitive and unreliable.131,132 Instability should be suspected in the presence of a positive stability test in conjunction with other clinical findings and symptoms of instability. A positive stability test in the absence of other clinical findings is probably irrelevant. Hypermobility is clinically manifested by the presence of increased physiologic range in one or more directions, or normal range with pain and spasm at the end of that range.

Research indicates that skilled clinicians can distinguish subjects with symptomatic spondylolysis from LBP based on the finding of increased intersegmental motion at the level above the pars defect.133,134

The various stability tests are described in the specific chapters of this text.