Severe biomechanical lesions of the thoracic spine are seen less frequently than those of the cervical or lumbar spine. But when they occur, they may be serious if related to disc protrusion or a dynamic facet defect. Shoulder girdle, rib cage, spinal cord, cerebrospinal fluid flow, and autonomic visceral problems originating in the thoracic spine are far from being scarce. Common biomechanical concerns are the prevention of thoracic hyperkyphosis, flattening, or twisting, as each can be suspected to contribute to both local and distal, acute and chronic possibly health-threatening manifestations.


Thoracic Fixations

The study of the thoracic spine is often perplexing. It was Gillet's opinion that many fixations found in the thoracic spine were secondary (compensatory) to focal lesions in either the upper cervical spine or the sacroiliac joints. Thus, a maze of potential variables exists. Empiric evidence has suggested that many thoracic problems have their origin in its base, the lumbar spine or lower, while others are reflections of cervical reflexes. Also, a thoracic lesion may manifest symptoms in either the cervical or the lumbar spine. Foremost in an examiner's thoughts should be the recognition that the thoracic spine is the structural support and sympathetic source for the esophagus, heart, bronchi, lungs, diaphragm, stomach, liver, gallbladder, pancreas, spleen, kidneys, and much of the pelvic contents. Referred pain and tenderness from these organs to the spine are common.


Screening Thoracic Vertebral Fractures

Thoracic fractures occur most frequently at the T12 transitional area, next in the midthoracic (kyphotic apex) region. Most are compression fractures with collapse of a vertebral body. Midthoracic fractures generally result from falls on the pelvis or when the head is severely forced between the knees.

Fractures of the thorax sometimes occur during convulsions or seizures and usually occur in the T5–T7 region. The mechanism is strong abdominal contraction accompanied by paraspinal cervical and lumbar spasm. This places the midthoracic area under severe compression forces.

Gozna/Harrington point out that bending moments and axial compressive forces produce compressive normal stresses that are cumulative at the anterior portion of the thoracic spine. They feel this fact explains the high incidence of spinal fracture in the thoracic region.

Soto-Hall Test

The Soto-Hall test is primarily employed when fracture of a vertebra is suspected. The patient is placed supine without pillows. One hand of the examiner is placed on the sternum of the patient, and a mild pressure is exerted to prevent flexion at either the lumbar or the thoracic regions of the spine. The other hand of the examiner is placed under the patient's occiput, and the head is slowly flexed toward the chest. Flexion of the head and neck toward the chest progressively produces a pull on the posterior spinal ligaments from above. When the spinous process of the injured vertebra is reached, acute local pain is experienced by the patient.

Roentgenography

Fracture lines are rarely recognized within vertebral bodies unless the area is crushed. These fractures are usually the result of considerable violence such as sudden extreme flexion, a heavy crushing injury, or extreme muscular exertion. Abnormalities in outlines and relations with neighboring vertebrae are the usual findings, especially in the lateral view. There are two general centrum types of fracture: compression and comminuted.

Compression fractures vary from a single slight irregularity in the anterior or lateral margins of the vertebral body similar to a long-bone torus fracture to a complete collapse of a portion of the centrum. Milder forms are usually asymptomatic, but there may be persistent local tenderness. Chronic vertebral compression forces such as occurring in trampolining or horseback riding accidents are usually diagnosed without difficulty except for the active adolescent with end-plate irregularities. Vertebral margin irregularities usually point to old trauma or infection.

Comminuted fractures are the result of greater trauma in which the vertebra is severely shattered by either direct violence or another vertebra impacting it.

Neural Arch Fractures.   In comparison to vertebral body fractures, fractures of the neural arch including the articular processes are more disabling because of the neuroreceptor irritation increased by motion or distortion. Fortunately, they are infrequently seen. Demonstration of a definite break is often difficult in the thoracic region, but callus formation later offers indirect evidence. Unlike vertebral bodies, the posterior aspects of the vertebral motion unit readily form a callus that becomes calcified in a few weeks. Severe acute traumatic subluxation may call attention to a subtle fracture.

Transverse Process Fractures.   Fractures of the transverse processes are usually multiple among adjacent vertebrae, but single processes may be broken by a blow from a sharp object. A slight callus can be expected, and fibrous union sometimes develops. Black lines formed by muscle shadows crossing transverse processes should not be confused with fracture. Muscle lines are smooth, straight, and extend beyond the bony margins.

Fracture vs Infection.   Traumatic lesions are sometimes difficult to distinguish from infectious lesions. Traumatic lesions usually reveal a substantial portion of the intervening disc still present, while the disc commonly disappears or greatly thins in prolonged infection. The infectious process is frequently accompanied by or an extension of a paravertebral abscess.

Scapular fractures are not frequently seen. In severe trauma, however, fractures of the body and spine of the scapula can occur. The strong muscular attachments usually prevent significant displacement. All that is usually required in uncomplicated cases is rest in a sling until acute pain subsides, then early mobilization. In rare cases, the brachial plexus or axillary nerve may be injured. Fractures of the scapular neck (uncommon) are usually impacted and present little displacement. Acromion fractures are the result of a downward blow on the shoulder, often leading to avulsion of the brachial plexus. Fractures of the coracoid process, easily confused with an ununited epiphysis, are uncommon; and when they occur, they are usually associated with acromioclavicular separations.

      PATHOLOGIC CONSIDERATIONS

Pain, both local and referred, and paravertebral thoracic spasm are common manifestations of local and/or visceral disorders. The possibility of myelopathy, nerve root irritation, and bone disease should be weighed against the common complaints of a postural origin. Arthrosis, spondylosis, osteochondrosis, gout, and osteoporosis are common pathologies affecting the thoracic spine producing or contributing to biomechanical faults and spinal distortions affecting spinal design, dynamics, and equilibrium. Only a thorough physical, orthopedic, neurologic, blood, and roentgenographic examination will help differentiate the many possible syndromes that have their origin in the thoracic spine.

Spinal Tumors.   A gross screening test can be performed by having the patient sit or recline while the examiner holds digital pressure over the jugular veins from 30–45 seconds (Naffziger's test). The patient is then instructed to cough deeply. Pain following the distribution of a nerve may indicate nerve root compression. Though more commonly used for low back involvements, thoracic and cervical root compression may also be aggravated. Local pain in the spine does not surely indicate nerve compression; it may suggest the site of a strain, sprain, or another type of lesion.

Naffziger's test is almost always positive in the presence of cord tumors, particularly spinal meningiomas. The resulting increased spinal fluid pressure above the tumor causes the growth to compress or pull sensory structures to produce radicular pain. The test is contraindicated in geriatrics, and extreme care should be taken with anyone suspected of having atherosclerosis. In all cases, the patient should be alerted that jugular pressure may result in vertigo.

Scheuermann's Disease.   Osteochondrosis of the vertebral plates is sometimes associated with backache (thoracodynia) and round shoulders in adolescents. It can be asymptomatic and is unlikely to be associated with sports injury except when activity results in a superimposed injury. This growth disturbance of the vertebral epiphyseal ring results in deformity of the vertebral end plate with formation of Schmorl's nodes, vertebral body wedging, and a smooth kyphosis. Taut hamstrings are often associated. Unless symptoms and signs are severe, corrective adjustments and therapeutic exercises may allow continued sports participation with close monitoring.

Ankylosis.   To check for ankylosis, chest measurements are taken after the patient inhales and exhales completely (chest expansion test). A 2-inch difference is a negative sign (may be less in females). A positive sign is indicated by no or very little difference in measurements and suspect of spinal ankylosis or spondylitis. Roentgenography offers confirmatory evidence.

Spinal Meningitis.   Two physical tests are helpful in supporting a suspicion of meningitis.

1. Brudzinski's test:   A positive sign is elicited when the patient's head is passively flexed toward the chest that is followed by involuntary flexion of the lower limbs. Such a reaction is indicative of meningeal irritation. The neck is rigid and painful to flexion and, in most cases, also to rotation. This test is unreliable in children below 2 years of age.

2. Trousseau's line test:   This sign of meningitis consists of a bright red line produced where the finger is drawn across the trunk or forehead. Diagnosis is confirmed by a spinal tap.

      PERTINENT FUNCTIONAL ANATOMY OF THE THORACIC SPINE

Unlike the rectangular centrum of a cervical or lumbar vertebra when viewed laterally, the body of a typical thoracic vertebra is wedge shaped, with its posterior aspect 1–2 mm higher than its anterior aspect. For this reason, lines drawn through the inferior vertebral body planes on a lateral roentgenograph normally meet anteriorly. This osseous wedge produces the relatively stiff primary thoracic kyphosis and encourages acquired exaggeration after prolonged axial loading.

The Articular Facets.   The flat oval superior articular facets face posterior and superior near a 60° angle, with a slight lateral slant to match the inferior facets above. From above, they appear as an arc of a circle whose axis is slightly anterior to the vertebral body.

A common error in adjusting the thoracic spine is to direct the force closer to an 80 ° angle than the proper 60° angle. An improperly directed force on facets produces a jamming, rather than a sliding, action resulting in articular trauma. However, one should rely on individual roentgenographic findings rather than textbook averages.

The Intervertebral Discs.   Thoracic spine flexibility is minimal because disc height in comparison to vertebral body height is less in the thoracic spine than that of any spinal region. This is readily apparent by noting there is little decrease in the thoracic curve on forward flexion or in the supine or sitting positions.

Unlike the cervical and lumbar regions, thoracic disc spaces are fairly parallel rather than wedge shaped. Thus, the primary thoracic kyphosis is produced by bone while the secondary cervical and lumbar lordoses are produced by fibrocartilage. Also, a thoracic nucleus sits slightly more central within the anulus. It is more posterior to the midline in the cervical and lumbar regions. This means the thoracic apophyses play less of a role in dispersing axial forces.

During axial rotation, oblique anular fibers running in the direction of rotation become tensed while those coursing in the opposite direction relax. This twists the anulus, but there are no appreciable shear forces involved in the thoracic spine during pure axial rotation.

The Spinal Muscles.   As mentioned in earlier papers of this series, little muscle activity is necessary to maintain the erect posture if the weight-bearing structures are in good alignment and the ligaments are healthy. It would then appear logical that if distortion exists, greater muscle activity and ligament strength are necessary to maintain balance. Many medical and chiropractic authors emphasize this in scoliosis and exaggerated A-P spinal curves, as well as in hip deformities; genu varum, genu valgum, and recurvatum; pes planus, etc.

In most approaches to functional scoliosis, it has been presumed that the initial distortion is muscular in nature; ie, either agonist weakness on the side of the convexity or hypertonicity or spasticity of antagonists on the side of the concavity. Here, attention is on the strong posterior and intrinsic spinal musculature. This purely kinesiologic approach must be considered against facts brought out by research studies.

• Cailliet points out that electromyographic studies on paraspinous muscles in idiopathic scoliosis fail to reveal significant muscle activity on either side of the curvature.

• Roaf's experiments have added to the complexity of understanding the etiology in all cases of scoliosis. He shows that unilateral shortening (eg, abdominal wall hypertonicity) of the prevertebral components of the spine relative to the posterior component results in severe lateral distortion of the spine. This would appear to support but not necessarily confirm the theory of T. J. Bennett that many situations of scoliosis are the result of noxious viscerosomatic reflexes.

Effects of Righting Reflexes on Scoliosis.   Experiments by Ponsetti and associates show unilateral labyrinthine stimulation or removal can result in scoliosis. This points to the delicate relationship between righting reflexes and spinal balance and offers an explanation to how cervical disrelationships with vertebral artery or vasomotor effects can produce scoliosis. Yamada et al found that 99 out of 100 scoliotic patients studied had an associated equilibrium defect and that the greater the spinal distortion, the greater the dysfunction in the proprioceptive and optic reflex systems. However, this finding has not been confirmed by studies in this country.

The Spinal Ligaments.   In comparison to the cervical and lumbar regions, the elastic ligamentum flava and the anterior and posterior longitudinal ligaments are thicker and stronger in the thoracic region. On the other hand, the interspinous and capsular ligaments are thinner and looser in the neutral position. These latter ligaments receive support from ligaments radiating from the costovertebral and costotransverse joints.

      KINESIOLOGY OF THE THORAX

The major muscles of the trunk, their functions, and their innervation are shown in Table 1.


Table 1.   Major Muscles of the Trunk

Muscle	Major Functions	Spinal Segment
Diaphragm	Inspiration	C4
Erector spinae	Extension	T1–S3
External oblique	Rotation, flexion, forced respiration	T1–T11
Intercostals, external	Inspiration, extension	T1–T11
Intercostals, internal	Expiration, extension	T1–T11
Interspinalis	Extension, lateral flexion, rotation	T1–S3
Intertransversarii	Lateral flexion, rotation	T1–T8
Internal oblique	Rotation, flexion, forced respiration	T7–T11
Longissimus dorsi	Extension	T1–L5
Multifidus	Extension, lateral flexion, rotation	T1–S3
Quadratus lumborum	Extension	T12–L3
Rectus abdominis	Flexion, forced respiration	T7–T11
Rotators	Extension, lateral flexion, rotation	T1–S3
Semispinalis	Extension, lateral flexion, rotation	T1–S3
Serratus posterior inferior	Expiration	T9–T11
Serratus posterior superior	Inspiration	T1–T4
Spinalis thoracis	Extension	T1–S3
Transverse abdominis	Forced respiration	T7–L1

Note:   Spinal innervation varies somewhat in different people. The spinal nerves listed here are averages and may differ in a particular patient; thus, an allowance of a segment above and below those listed in most text tables should be considered.

Movements in the thoracic spine are relatively limited compared to those of the cervical area, especially in the upper region, due to the restrictions imposed by the costovertebral and costotransverse articulations, the direction and shape of the articular facets, the relatively thin discs, and the tension of the ligamentum flava.

All thoracic movements are somewhat three-dimensional. Rotation and lateral flexion are the most evident. Movement of the thoracic spine cannot occur in any direction without the involved vertebrae somewhat carrying their attached ribs with them.

Flexion and Extension.   Flexion and extension of the thoracic spine are quite limited. An average of only 4° occurs in the upper discs, 6° in the middle discs, and about 12° in the lower discs. As in the other spinal areas, excessive A-P motion is restricted by the check ligaments, but the thoracic cage adds an additional mechanical barrier to flexion and intercostal straps to restrict extension.

Thoracic extension from full flexion takes places in two phases:

(1) The articular surfaces glide posterior and inferior, the interspinous spaces diminish, and the stretched posterior anulus of the disc returns to its neutral shape as the individual achieves the erect position. There is no appreciable change in the anterior portion of discs or nucleus.
(2) It is not until the shingle-like facets, transverse processes, and spinous processes reach their limit as the spine is extended posteriorly to the midline that the anterior portion of discs and anterior intercostal spaces begin to widen. On forced extension, the articular processes impact. The vertebrae then push between their ribs, and the rib heads and their angles are moved slightly aside by the transverse processes.

Thoracic A-P mobility includes a good amount of facet gliding, but it is far less than that of the cervical region where the facets almost separate on forward flexion. Because of the rather limited normal movement of the thoracic spine, gross idiopathic scolioses in this area are difficult to comprehend when little structural damage is present.

As in other spinal areas, the anulus and its nucleus bulge in opposite directions during A-P and lateral bending moments to stabilize each other. During forced extension, the anulus thins and bulges posteriorly and stretches and contracts anteriorly. The nucleus bulges anteriorly without appreciable shifting. The anterior ligaments tense while the posterior ligaments relax. At the end of forced extension, the inferior facets tend to pivot open anteriorly as their posterior aspect jams on its neighbor below. These actions are fairly minimal when the normal kyphosis is present, but it may be exaggerated in the flat "military" spine. During flexion, the mechanisms are essentially the opposite.

Rotation.   Rotation of the thoracic spine, usually coupled with some vertebral body tilting, is somewhat greater than flexion and extension that are approximately equal in range. Rotation up to about 10° occurs at the T1 segment but progressively diminishes inferiorly to a maximum of 2° –3° at the T12 area. The total range of thoracic rotation is about 40°. Grice reports there are also a few degrees of coupled flexion during upper thoracic rotation and a few degrees of coupled extension during lower thoracic rotation. This becomes a significant point in analyzing scolioses.

Rib Changes.   During thoracic rotation, the spine does not rotate between the ribs but with the ribs. This is accompanied by a degree of lateral gliding of the vertebrae involved. However, when rotation is forced beyond the limit of rib motion, there is a slight push by the transverse processes against the rib heads on the side moving anteriorly and a slight pull by the transverse processes on the rib heads moving posteriorly. This motion is often revealed by dynamic palpation, rarely by roentgenography. It is recognized easier in the upper thoracic region where rotation is greater and the ribs are firmly attached to the sternum than in the lower thoracic area where the floating ribs more readily follow vertebral movement.

According to its design, the thoracic spine would have a considerable range of rotary motion if it were not for the restricting thoracic cage. This is seen in scoliosis where every movement of the spine is registered by a corresponding movement in the attached ribs.

Lateral Flexion.   Although lateral flexion is hampered by the rib cage, the average person should be able to touch the ipsilateral knee with the fingertips. In the average adult spine, less than 10° of motion occur at the upper and middle discs, and a few more degrees of motion are attained by the lower discs. The total range of lateral flexion for the healthy thoracic spine is slightly greater than 50°.

During lateral flexion in either the neutral or the flexed (Adams) position, there is some coupled rotation where the upper vertebral bodies swing toward the concave side and the spinous processes rotate toward the convexity as in the cervical spine. This bending-rotation requires anterior transverse process movement pushing against the respective rib on the convex side and posterior transverse process movement pulling away from the rib on the concave side. This is the primary restricting mechanism. The ligaments play only a minor role except in traumatic forces.

In the lower thoracic segments, the vertebral bodies swing toward the convex side and the spinous processes rotate toward the concavity as in the lumbar spine. However, Grieve states that an opposite effect occurs during lateral flexion when the spine is in the extended position and vertebral body rotation is toward the convexity in the upper thorax and toward the concavity in the lower thoracic region. This fact tends to explain how various primary subluxations influence the direction a scoliosis will take; ie, a focal vertebral motion unit locked in either neutral, flexion, or extension.

Some authors give more credit to the thoracic ligaments than they deserve because they study the thoracic spine separate from the rib cage. But it is not separate in vivo, and studying the spine by itself does not reveal the total mechanics involved (eg, using a plastic model of the spine). A thoracic spine detached from the rib cage is fairly flexible in all directions except extension.

If the thoracic ligaments are supple (eg, those of a child), the ribs react to this movement of the transverse processes and enhance rotation. The rib spaces on the convex side will not open until the ribs on the concave side have reached their limit of approximation. In the adult thoracic spine, however, there is little rotation accompanying lateral bending except in the lower thoracic region where the ribs "float." On forced lateral bending where the ribs approximate on the concave side and their limit is reached, the associated vertebrae are capable of slight additional lateral gliding.

Note:   The position of a thoracic vertebra in lateral flexion is identical to that of the common subluxation in the neutral position where one facet has slipped inferoposteriorly while its counterpart has glided superoanteriorly.

      BIOMECHANICAL INSTABILITY

As explained previously, it is fallacy to consider the thoracic spine biomechanically apart from the rib cage. The attached ribs, although individually quite flexible, offer increased stiffness and strength to the vertebral segments. The thoracic spine's moment of inertia is increased by the rib cage, which also increases the area's stiffness against torques and bending moments. The stiffness property of the thoracic spine is decreased at least in half in all loading directions once the ribs are removed.

It has been explained that the thoracic cage is stressed during axial rotation so that the ribs are pushed posteriorly on the side of movement and pulled anteriorly on the other side. This subjects the sternum to shear forces, and the sternum minutely tips obliquely toward the direction of rotation.


Unique Factors of the Thoracic Spine

Several unique factors arise regarding the stability of the thoracic spine have been explained. In review, the major points are that it

      BIOMECHANICAL ARTHROLOGY OF COSTOVERTEBRAL
      AND COSTOTRANSVERSE JOINTS

In terms of biomechanical stability, the costovertebral joints exhibit their highest stiffness property in the lateral direction and their lowest stiffness against superior or inferior loading. The sternocostal joints are just the opposite. They exhibit higher resistance against vertical forces and lower resistance against A-P forces.

Note:   Because of the low stiffness property in cephalad-caudad loading, an adjustive force placed too far laterally can easily sprain one or more costovertebral and/or costotransverse joints.

The Costovertebral Joints.   Posteriorly, the convex-shaped head of a rib articulates (slides and pivots) on two adjacent thoracic vertebral bodies at the concave demifacets, above and below disc level. This occurs within a richly innervated synovial joint. Exceptions to this motion are the 1st rib and floating ribs whose heads articulate with only one vertebra.

The capsule of a costovertebral joint is typically quite thin and weak by itself but stronger anteriorly than posteriorly. It is attached to the anulus via the intermediate intra-articular ligament, which divides the cavity and attaches to the rib head between the facets. Interosseous fibers also extend from the rib head superiorly to the vertebral body above and inferiorly to the vertebral body below. These intermediate, superior, and inferior fibers strengthen the inherently weak capsule proper. Capsule fibers merge posteriorly with the lateral extensions of the posterior longitudinal ligament. During inhalation, the rib heads undergo a slight rotatory and gliding movement.

The Costotransverse Joints.   As a rib is directed posteriorly from the attachment of its head, a convex posterior tubercle on the rib articulates with a concave facet on the anterior tip of the transverse process of the same thoracic vertebra. This is also a richly innervated synovial joint that allows lubricated movement. The T1–T7 joints are concave-convex shaped to allow rotation, while the T8–T10 joints are flat to allow gliding.

Strength is provided to the thin capsules by medial and lateral costotransverse ligaments. A strong superior costotransverse ligament connects an adjacent rib neck below to the transverse process above, but it offers only slight protection to the costotransverse capsule. During inhalation, the tubercles glide superiorly and posteriorly. The lower two or three ribs have neither articular tubercles nor costotransverse joints.

Costovertebral and Costotransverse Coupling.   Kapandji points out that the costotranverse joint and the costovertebral joint serve as a mechanical couple restricting normal movement to only rotation about an axis that passes through the center of each of these joints. These joints, along with the elasticity of the sternocostal articulations, produce pivot points from which the ribs elevate and depress laterally.

Because the axis running through the costotransverse and costovertebral joints lies close to the frontal plane in the upper ribs and nearly parallel to the sagittal plane in the lower ribs, elevation of the ribs during inhalation appreciably increases only the A-P diameter of the upper thorax, increases both the A-P and transverse diameters in the mid thorax, and increases only the transverse diameter of the lower thorax. All these changes of thoracic diameter can be accomplished by the diaphragm itself.

Scapular Coupling.   For every 3° of lateral arm abduction, 1° occurs at the scapulothoracic articulation for every 2° at the glenohumeral joint. If you wish to check solely glenohumeral joint passive abduction, your stabilizing hand should anchor the scapula while your active hand passively abducts the patient's arm horizontally. The shoulder blade will normally not be felt to move until about 20° of abduction have occurred. Abduction normally continues in this position to about 120° where the surgical neck of the humerus meets the tip of the acromion. Then turn the patient's forearm to externally rotate the humerus, turn the surgical neck away from the acromion, and continue abduction to its maximum.

Abduction is painful against resistance in shoulder tendinitis. In the "frozen shoulder" syndrome, scapulothoracic motion will be normal and glenohumeral motion will be absent.

Note:   It has been the author's experience that about 60% of complaints of pain in the lateral upper arm on abduction, including local tenderness, will be found to be primarily due to scapular mobility restriction.

General Problems of the Back and Thoracic Spine

Grieve points out that it is a rare thoracic spine that does not exhibit some areas of tenderness when palpated. There are probably more trigger points and reflex fasciculations located on the thoracic cage than any other area of the body.

The thoracic region can be considered a highly critical zone, even though the predominance of current literature emphasizes the importance of its neighboring regions. It can be said that the thoracic spine suffers the "middle child syndrome" from an orthopedic viewpoint. It is just as important as its structural brother and sister above and below, yet fails to receive the same attention.

Note:   May we remember that chiropractic pioneers took their greatest steps forward when "Meric analysis" was in vogue –long before preoccupation was placed upon the atlas and sacrum. These were the days when the profession was accused of being undereducated and overmotivated. But these were the days when chiropractic "miracles" were taken for granted.

Postural Disorders of the Upper Trunk

To gather as many facts as possible during differential diagnosis, a comprehensive postural evaluation should include a comparative analysis of the physical signs found in the standing, sitting, Adams, prone, and supine positions.

Many clinicians believe that the causes of pain and discomfort in the shoulder girdle can usually be traced to muscular overuse leading to lower cervical or upper thoracic subluxations. While this is often true, fixed misalignments may be found in the shoulder girdle, especially when the scapulae are chronically affected. Acute or chronic fibrositis of the trapezius and rhomboids with trigger points is often superimposed or consequential. Such syndromes are often found in typists, assembly-line workers, and laborers who work overhead with repetitive motions for long duration with little postural change.

Note:   Because chiropractors see so many neuromusculoskeletal conditions arising from the spine, it takes self-discipline not to develop tunnel vision because of these experiences. The author has served as a consultant in five cases during the last 2 years in which the patient complained of paresthesia (eg, numbness) in one or both index and middle fingers in which a thorough trial of cervical adjustments failed to bring adequate relief. All five cases had been diagnosed by allopaths as having carpal tunnel syndrome. It was found that one patient was suffering diabetic neuropathy, another advanced arteriosclerosis, and the remaining three experienced permanent relief simply by correcting fixations existing in the elbow (two patients) or wrist (one patient). Thus, we should not overlook the fact that the spine is just one concern in which the vasomotor system may be adversely affected.

Postural Patterns and Classes

Any postural pattern is a reflection of an individual's biomechanics responding to underlying processes. The process may be essentially antalgic, muscular, ligamentous, osseous, proprioceptive, visceral, or a combination of these factors.

DeJarnette believed that many idiopathic patterns reflect massive movement of structure held in a state of fixation by increased myosensory input. Goodheart places emphasis on muscular weakness, usually of a reflex etiology, and Barge feels the initial distortion is frequently the result of a nuclear shift. B. J. Palmer felt they were the result of proprioceptive or motor disturbances originating in the upper cervical area, and Hugh Logan felt they were responsive mechanisms to sacral base inferiorities. Today, few would disagree that all such mechanisms can be involved singularly or in combination.

There is always a danger in describing classic patterns because they lead to such variances in subjective interpretation. There is almost no limit to the possible distortions that may occur. Classifications tend to encourage the examiner to try to fit an individual's unique distortion into a certain arbitrary category. This limits thought and can lead to error. Patterns only offer visual and palpable clues that require challenging by thorough diagnostic procedures.

Standard muscle testing and inspection may disclose a pathologic weakness in the absence of palpable or measurable atrophy. This type of relative muscle weakness in comparison to its antagonist is often associated with a palpable trigger point at the origin and/or insertion of affected muscles. For example, a weak quadratus lumborum is frequently found associated on the side of pelvic slant and lumbar rotation (eg, a functional short leg). If this is the case, increasing the muscle's strength tends to normalize the pelvic level and consequent thoracolumbar rotation. Any distortion produced by muscular hypo- or hyper-activity is an indication of debilitating postural stress. Seek the cause.


Postural Realignment and Structural Fixations

The entire thoracic region is prone to a number of types of muscular and ligamentous vertebral and costovertebral fixations. Gillet believed that primary thoracic fixations generally tend to produce secondary areas of fixation in the cervical spine.

The lower thoracic region (T9–T12) is probably more prone to fixation than any other area of the spine. This is likely due to the abrupt change in facet planes between the superior and inferior processes of the transitional vertebra, the altered stiffness between thoracic and lumbar vertebrae, the lack of strong supporting muscles enjoyed by the lumbar region, the lack of firm anterior support by the floating ribs, and the large compressive forces concentrated at this area. A sudden change in the stiffness properties of a structure at a given point subjects the structure to stress concentration at that point. This can lead to eventual failure.


General Realignment Through Myotherapy

In postural alignment of functional thoracolumbar curves, the common muscles requiring strengthening are

(1) the quadratus lumborum on the side of concavity,
(2) the upper and lower trapezius and the major and minor rhomboids to improve scapular adduction and rotation, and
(3) the infraspinatus and teres minor to improve lateral rotation of the shoulder.

It is also unusual in thoracolumbar distortions that certain muscles do not need stretching such as

(1) the quadratus lumborum on the side of lower thoracic convexity,
(2) the latissimus dorsi, teres major, and subscapularis to improve shoulder adduction and medial rotation, and
(3) the pectoral group to improve shoulder adduction and medial rotation. Invariably, stretching of the intercostals on the side of thoracic concavity is necessary.

The common muscles to be stretched in postural misalignment restricted to the thoracic spine and shoulder girdle are the shoulder adductors and medial rotators; eg, the latissimus dorsi, teres major, subscapularis, and pectoralis major and minor. When these muscles are stretched, the scapula should be firmly stabilized.

In the therapeutic alignment of the thoracic spine and shoulder girdle following adjustive therapy, the common muscles to be strengthened are the scapular adductors and rotators; eg, trapezius, rhomboid major and minor, infraspinatus, and teres minor. An associated weakness will invariably be found in the gluteals and abdominals, inducing primary or secondary pelvic misalignment.


Specific Muscle Hypertonicity

Most fixations seen in the thoracic area are muscular in type. This is fortunate because difficult to manage fibrotic pseudoankylosis can readily develop in the thoracic spine. While this would not contraindicate manipulation, the tough tissues adapt slowly. Correction typically takes frequent care using a wide scope of therapy over many months, if not years, to obtain an appreciable change because of the poor vascularity of the tissues involved.

The Interspinous and Intertransverse Muscles.   Bilateral interspinous and/or intertransverse muscle hypertonicity produces extension fixation. In unilateral intertransverse hypertonicity, the involved transverse processes approximate, the discs thin ipsilaterally, and the height of the IVFs is reduced. The superior articulation is pulled into a stressed position away from the inferior process (facet syndrome). The articular spaces have an abnormal V-shaped appearance. The IVD spaces increase at the anterior and decrease at the posterior. The acute stage is due to muscular spasm. But in prolonged conditions, the ipsilateral muscles become fibrotic and the paravertebral ligaments shorten. Stretching occurs on the contralateral side.

The Rotatores.   A unilateral hypertonic rotatores, which courses in the groove between the spinous and transverse processes, will pull the corresponding spinous process into rotation and the transverse process below into counterrotation, similar in effect to that of intertransverse hypertonicity. This unilateral state, usually acute, commonly extends over several thoracic segments.

Bilateral rotatores hypertonicity, often a generalized reflex condition in the thoracic spine, tends to initiate the interspinous syndrome. Rotation is restricted, and lateral bending is almost nil. This state is more readily palpable in the upper dorsal area and usually accompanied by bulging levator costarum muscles. Gillet believed that this disorder is frequently secondary to a primary fixation in one or both feet.

The Rhomboids.   The rhomboideus major arises from the spinous processes of T2–T5 and inserts at the vertebral margin of the scapula. The rhomboideus minor connects the spinous processes of C7–T1 and the lower part of the nuchal ligament to the vertebral margin of the scapula at the root of the scapular spine. As their function is to retract and fix the scapula, hypertonicity of these muscles produces this normal function in a fixed state. In unilateral involvement, the scapula is pulled medially and upward so that the ipsilateral shoulder is higher than the other. This condition, sometimes secondary, is infrequently symptomatic even though a postural distortion may be quite evident.

Ligament Shortening

The Anterior Longitudinal Ligament. Shortening of the anterior longitudinal ligament is a common site of fixation in the thoracic spine, but it's rare in the lumbar region. It displays on a lateral roentgenograph as an increased kyphosis and decreased anterior disc spaces and may be confused with anulus degeneration, which may or may not be present. IVFs will appear elongated. Gillet believed that this traction appears to have considerable effect on the sympathetic nerves (visceral symptoms), be a source of noxious reflex activity, but have little or no effect on somatic nerves.

The Posterior Longitudinal Ligament. For some unexplained reason, shortening of the posterior longitudinal ligament is rarely found. This could possibly be explained by the greater flexion exercise required in normal activity, keeping in mind that A-P and P-A thoracic motion is minimal at best. While this may explain the thoracic state, one would think that these ligaments would be shortened in chronic cervical or lumbar lordosis, but this is rarely demonstrated.


Trapezius Contusions

Most trapezius bruises will be found in the proximal portion, rarely distal to the scapular spine. That aspect between the occiput and the shoulder is the only significant muscle that can resist forceful shoulder depression. It is also this aspect that suffers contusion from a blow to the body from above that strikes lateral to the neck.

Posterior Thoracic Strain

The upper trapezius strain syndrome, often loosely labeled cervical fibrositis, is frequently found in patients who have a postural forward head displacement. The head position, which may be compensatory, is associated with a fixed rounded (kyphotic slump) curvature of the upper spine, resulting in fixed hyperextension of the cervical spine and restricted hyperflexion of the upper thoracic spine.

Undue spinal compression posteriorly (on the facets of the vertebrae) is characterized by a flattened area within the normal thoracic kyphosis. The typical clinical picture is posterior neck pain, weakness of anterior neck flexors, and tenderness of the upper dorsal transverse processes. Tension of neck extensors, including the upper trapezius and cervical erectors, causes chronic fatigue and an ache at the base of the neck. The patient frequently stretches the lower neck in an attempt to gain relief. A related impingement of suboccipital nerves as they emerge through fascia and muscle at the base of the skull may account for the commonly associated occipital headaches.

Middle Posterothoracic Strain.   A painful mid-back disorder can result from gradual and continuous tension on the middle and lower trapezius fibers (a stretch-weakness condition). The chief problem is excessive tension on the posterior thoracic muscles. There is also an issue of undue compression on the anterior surfaces of the bodies of the thoracic spine, exhibited by hyperkyphosis and depression of the anterior rib cage. Common causes are habitual posture position of forward (round) shoulders and a rounded upper back, overdevelopment of the anterior shoulder girdle muscles with shortening, or heavy breasts that are not adequately supported.

Lower Posterothoracic Strain.   This state of chronic muscle strain is rarely associated with an acute onset, but the symptoms may reach a point of severe pain after unusual physical activity. The syndrome is characterized by initial soreness and fatigue that progresses to a burning sensation within the course of the middle and lower trapezius. Traction by the muscle on its bony attachments may cause complaints of an isolated sore spot or trigger point. Palpation frequently elicits acute tenderness in the region of the dorsolumbar attachment of the lower trapezius.

Teres Spasm Sign.   When the relaxed standing patient is viewed from behind, the arms normally rest so that the palms face the thighs. If a palm faces distinctly backward (toward the examiner) on the involved side, a spastic contraction of the teres major muscle is suggested.

Thoracic Spine Sprains

Acute traumatic spondylitis may follow contusions or wrenching of the spine. As in sprains of other joints, the symptoms are pain, tenderness, and reflex muscle rigidity limiting function. Symptoms may appear immediately after injury or not become apparent for a few hours or days. Diagnosis is based on history, physical findings, and x-ray to exclude fracture and destructive pathologic lesions.

Concomitant Vertebral Subluxation-Fixation.   Posttraumatic thoracic subluxation complexes are managed in sports and industrial clinics as they are in general practice, but the athletic subluxation is more often associated with acute symptoms of paravertebral strain and sprain. Leverage adjustments on the medial transverse processes are preferred to pisiform recoil corrections with a spinous process contact. Because of the athlete's heavy muscles, moist heat prior to correction is helpful, as a rule, in relieving spasm unless acute symptoms make heat contraindicated.

Concomitant Thoracic Disc Herniation.   Protrusion of a thoracic disc is the least common of any spinal region. It occurs predominantly in males over 50 years of age, commonly occurring in the T11–T12 area. The clinical picture is relative pain, usually unilateral in chronic cases or bilateral in acute cases, with girdle-like distribution. The pain may radiate to the abdomen, flank, or groin. Spastic paraparesis with sensory complaints may be involved. Bowel and bladder incontinence and impotence are infrequently associated. Motion restriction and tenderness on percussion may be the only local physical signs. Hyperactive tendon reflexes in the lower extremity and a positive Babinski are sometimes found. Common differentiation must be made from intercostal neuralgia, ankylosing spondylitis, metastatic or intramedullary spinal cord tumors, neurofibroma, disc-space infection, and viscerosomatic reflexes.

Management.   During the acute hyperemic stage, structural alignment, cold, strapping or bracing, positive galvanism, and rest are indicated. After 48–72 hours, passive congestion may be managed by light massage, gentle passive manipulation, sinusoidal stimulation, ultrasound, and a mild range of motion exercise. During the stage of consolidation, local moderate heat, moderate active exercise, motorized alternating traction, moderate range of motion manipulation, and ultrasound are beneficial. In the stage of fibroblastic activity, deep heat, massage, active exercise, motorized alternating traction, negative galvanism, ultrasound, and joint mobilization speed recovery and inhibit postinjury effects.

Scapular Fixations

Restricted movements are commonly found in the scapular area that influence physical performance and posture. Their usual causes are

(1) the consequence of injury,
(2) trigger-point spasm, or
(3) viscerosomatic reflexes.