Figure 6.1
The thoracic spine
Introduction
The thoracic spine is a common site for dysfunction, including rheumatological (e.g. ankylosing spondylitis), infective (e.g. tuberculosis), metabolic (e.g. Paget’s disease) and degenerative (e.g. osteoporosis) problems, to name a few. In comparison to the lumbar and cervical spine, the thoracic spine has received less focus in epidemiological, clinical and occupational research (Briggs et al 2009a). One explanation for this is that researchers investigating back pain have often grouped lumbar and thoracic spine pain into one category (Briggs et al 2009a). In a study by Dionne et al (2007), thoracic spine pain was found to be a major factor in working hours lost and reported work disability. Many occupations are at risk of developing thoracic spine pain, among them manual laborers, office workers, health professionals and drivers (Briggs et al 2009b), with some groups experiencing up to 50% incidence. Briggs et al (2009b) also found that females experienced a higher occurrence of thoracic spine pain than males.
Recent studies have found an increasing incidence of thoracic pain in adolescents (Wedderkopp et al 2001, Grimmer et al 2006, Trevelyan & Legg 2006, Jeffries et al 2007, Briggs et al 2009b). Some of this has been linked to poor posture or ergonomics within the classroom (Murphy et al 2004, Lafond et al 2007) or to the use of heavy school bags and backpacks for transporting books to and from school (Sheir-Neiss et al 2003, Skaggs et al 2006, Papadopoulou et al 2013). Links have also been made between thoracic spine pain and poor posture, inactivity and prolonged sitting when playing computer games (Zapata et al 2006, Hakala et al 2012). Back problems in adolescence could potentially cause further issues and problems as these young people progress into adulthood (Hakala et al 2002, Ståhl et al 2014). Kujala and colleagues (1999) found that up 10% of adolescents suffered thoracic spine pain to the point that it restricted their participation in activities. Thoracic spine pain is one of the factors that have been associated with an increase in painkiller consumption among adolescents participating in sports (Selanne et al 2014). Education about posture, ergonomics and training is therefore an important component when treating adolescent patients within the clinical environment.
Interestingly, Imagama et al (2014) found that an increase in thoracic kyphosis, increased spinal inclination and weak posterior musculature are factors associated with shoulder injuries and limitation of shoulder movement. Therefore good maintenance of the thoracic spine not only leads to decreased thoracic spine symptoms, but is also associated with healthy shoulder mechanics.
Articulation of the thoracic spine has been shown to be beneficial in decreasing pressure pain thresholds in that section of the spine. Fryer et al (2004) found that passive rhythmical repetitive articulation of the thoracic spine caused a greater decrease in the pain threshold of participants with thoracic spine symptoms than manipulation of the spine on a short-term basis. Furthermore, Cleland et al (2007) found that thoracic spine articulation caused a reduction in pain and disability in patients experiencing cervical spine pain, although significant reduction and relief were only short term and, like most research, these findings require further investigation to validate them and to investigate long-term effects.
Anatomy
The thoracic spine is one of three regions of the spinal column and is located in the middle segment of the spine, between the cervical spine in the neck and the lumbar spine in the lower back. It comprises 12 vertebrae (labelled T1 to T12) that caudally increase in size, reflecting the caudal increase in body load. However, although it is not common, the number of thoracic vertebrae in the spine can vary from 11 to 13 because they are usually defined by paired ribbearing elements. Early recognition of the precise number of thoracic vertebrae in a patient is important so that the discrepancy does not lead to inappropriate surgical planning, which may endanger the patient’s site of pathology (Wigh 1980).
The thoracic vertebrae are intermediate in size compared with vertebrae of other segments. The size and shape of the superior thoracic segment closely resembles the cervical vertebrae, whereas the inferior thoracic vertebrae are more similar to the lumbar (White & Panjabi 1978). These vertebrae curve inward and outward to give support and stability for the ribs and sternum. They play a significant protective role for the lungs, heart and major blood vessels and provide structure and flexibility for the body, while guarding the vertebral column (McKenzie & May 2006). The intervertebral discs from T1 to T12 also vary considerably in their size and shape.
The thoracic spine is more rigid than other spinal segments, due to the structural integrity provided by the ribcage and its articulations, facet orientations and vertebral body configurations. For this reason, unlike the cervical or lumbar spine, the thoracic spine is presumed to build for load transfer and stability. White (1969) suggested that the compressive load at the first thoracic vertebra (T1) was approximately 9% of the participant’s body weight, which increased up to 33% at T8 and 47% at T12. The vertebral bodies are thought to withstand and distribute the majority of this load. Edmondston and Singer (1997) state that, in order to accommodate this load, the vertebral body’s height, end-plate cross-sectional area and bone mass increase caudally, mainly in the middle and lower parts.
Its articulations to the ribcage mean that the thoracic spine is the least mobile segment of the vertebral column. Thin intervertebral discs also contribute to the lower mobility of the thoracic vertebrae, as they comprise only 1/7 of the vertebral body’s height. According to McKenzie and May (2006), the additional vertebral–rib joints (costovertebral and costotransverse joints) and the configuration of the zygapophyseal joints and the spinous processes are all factors that restrict the movement of the thoracic spine.
Bony anatomy
Vertebral bodies
The vertebral bodies of the thoracic spine are wedge-shaped, round blocks of bones that are larger posteriorly than anteriorly. They are concave on their cranial and caudal end-plate surfaces, flat above and below, deeper dorsally than ventrally, and slightly constricted laterally and in front. They vary substantially in their size and shape from T1 to T12, increasing considerably in more inferior segments. The vertebral bodies function primarily to support and transfer the weight of the trunk, because of the anterior concavity of the thoracic kyphosis (Singer & Goh 2000). The thoracic vertebral bodies also support two demifacets on each of their lateral posterior surfaces, superiorly and inferiorly adjacent to the end-plate surfaces. These are present for the articulation of the head of each respective rib bilaterally.
Vertebral arches
The vertebral arch is a thin, bony ring attachment at the posterior portion of each vertebral body. Each vertebral arch encloses the vertebral foramen and provides space for the spinal cord. It acts to protect the spinal cord and the roots of the spinal nerves (McKenzie & May 2006).
Pedicles
Pedicles are short bones that extend posteriorly from the vertebral body to form the vertebral arch. They act as a connector between the vertebral body and its posterior elements.
Laminae
Laminae are broad, thick bones that connect with the pedicles to complete the vertebral arch. They are the outer rim of the bony ring and form the posterior border of the vertebral foramen.
Transverse processes
The bony knobs that project from the lateral sides of each vertebral arch, one on the left and one on the right, are called transverse processes. They articulate with a pair of ribs, forming the costotransverse joints and provide attachment sites for muscles and ligaments.
Spinous processes
The spinous process is a long bony structure that is directed obliquely downward especially in the mid thoracic area. The spinous process extends so far downward that, in the mid thoracic area (T4–T8), it is level with the vertebral body of the vertebra below. It arises from the junction of the laminae and ends at a tuberculated extremity. It serves to attach several muscles of the back.
Articular processes
Articular processes are projections of the vertebra that spring from the junctions of the pedicles and laminae, and extend superiorly and inferiorly toward the adjacent vertebrae. There are four articular processes, two superior and two inferior, that project from a vertebra. They serve to stabilize the spine, forming a facet joint where they join with an adjacent vertebra (Moore et al 2013).
Ligaments
The thoracic spine has the same ligaments as elsewhere in the vertebral column. These include the anterior and posterior longitudinal ligaments, supraspinous and interspinous ligaments, intertransverse ligaments and the ligamentum flavum. However, the ligamentous support provided for the ribs by the thoracic spine also involves the costotransverse and radiate ligaments and the ligaments of the costovertebral joint capsule (Putz & Muller-Gerbil 2000).
Lang et al (2013) found that ossification of the ligamentum flavum was relatively common in the patients they examined, with a predictive occurrence of 63.9%. The peak occurrence of this was in patients between 50 and 59 years of age, but they did find some evidence of it occurring in adolescents between 10 and 19 years of age. The main area where this occurred was the lower thoracic spine between T10 and T12, and more commonly in males, which led Lang et al to suggest that it is triggered by higher mechanical stresses to the tissue.
Joints
Costovertebral joints
The costovertebral joints are formed when the head of the rib articulates with the costal facets of adjacent vertebral bodies and the intervertebral disc between. The heads of ribs 2 to 9 articulate with two vertebral bodies; the heads of ribs 1 and 10 to 12 connect with only one vertebra each. Each costovertebral joint is composed of a fibrous capsule, the fan-shaped radiate ligament and the interarticular ligament (Macdonald 1986).
Costotransverse joints
The costotransverse joints are formed when the tubercle of the rib articulates with the transverse process of the corresponding vertebra. These joints include the neck and tubercle ligaments, a capsule and the costotransverse ligaments. They are absent in T11 and T12 (Duprey et al 2010).
Zygapophyseal joints
The zygapophyseal joints, also known as the facet joints, are synovial, plane joints formed joining the articular processes of two neighboring vertebrae. They primarily serve to guide and constrain the motion of the vertebrae (Pal et al 2001). Manchikanti (2004) found that 42% of chronic thoracic spine pain originated from the facet joint.
Range of motion
Unlike the other spinal segments, where a considerable number of movement analyses have been performed, serious studies to evaluate the movement of the thoracic spine are very limited. Although there are reports of range of motion, they are based largely on an early cadaver study (White 1969). The study of thoracic movements presents significant methodological difficulties because it includes studying the ribcage and the complex interaction between the vertebrae and the ribs, and Valencia (1994) stated that the measurement of thoracic movements is technically difficult. However, a few in vivo and in vitro studies have been done that suggest some possible range of movements, but these give different measurements (see Table 6.1).
Epidemiology
The epidemiology of thoracic spine pain is hindered by two major drawbacks: the difficulty in defining the thoracic pain and the lack of high-quality literature. Moreover, there are very limited epidemiological data in relation to thoracic pain. Reviewers of the available data suggest that the clinical pain syndromes associated with the thoracic spine are less common than those associated with the cervical and lumbar regions (Lemole et al 2002). According to Singer and Edmondston (2000), the percentage of patients in the chronic pain clinic environment is only 2–3%.
Movement type | Motion unit | Range of motion (°) |
Flexion | C7–T1 | ≈ 9 |
4 | ||
4–8 | ||
T12–L1 | 8–12 | |
Lateral bending | ≈ 6 | |
T11–L1 | ≈ 8 | |
Sagittal | < 5 | |
≈ 5 | ||
Rotation | 8–12 | |
≈ 8 | ||
< 3 |
Table 6.1
Possible range of movement of the thoracic spine
Data from McKenzie & May (2006), Leahy & Rahm (2007)
Although limited literature is available on the epidemiology of thoracic spine pain, there are a few notable population-based studies. In one such study of age group 35–45 years, Linton et al (1998) reported that the annual prevalence of spinal pain in the general population was 66%. Only 15% of individuals with spinal pain symptoms reported pain in the thoracic spine region compared to 56% in the lumbar spine and 44% in the cervical spine. This equates to an annual prevalence of approximately 3% in the general population for thoracic pain. However, the percentage of thoracic pain prevalence varies between studies. According to the majority of reports, including surveys by osteopath clinics, chiropractors and physiotherapists, the thoracic pain prevalence range is between 2.6% and 14%. Considering these data, McKenzie and May (2006) stated that about 5–17% of all spinal problems are thoracic in origin (see Table 6.2).
Condition | Description | Reference |
Spinal canal stenosis | May result from either hypertrophy of the posterior elements of the thoracic spine or congenital deformation Often occurs in relation with generalized rheumatological, metabolic or orthopaedic conditions, such as osteofluorosis, achondroplasia, acromegaly, Paget’s disease or previous fracture Average age of presentation: 65 years | Barnett et al (1987), McRae (2010) |
Vertebral body fractures | Most common in the thoracolumbar spine Usually result from a high-energy accident or osteoporosis May also occur because of an underlying disorder, such as ankylosing spondylitis, a vertebral tumor or infection Symptoms include pain or the development of neural deficits such as numbness, weakness, tingling, spinal shock and neurogenic shock Predominant in men Age of presentation: 2nd to 4th decades | Kostuik et al (1991), Jansson et al (2010) |
Juvenile kyphosis | A form of juvenile osteochondrosis of the spine, which leads to wedge-shaped vertebrae Commonly affects the T7 and T10 vertebrae Usually occurs in adolescence, between 14 and 18 years of age Slightly predominant in women Results in lower and mid-level back pain, poor posture and increased kyphosis | Scheuermann (1934), Bullough & Boachie-Adjei (1988) |
Thoracic neurofibroma | One of the most common tumors of the spine Also known as neurilemmoma, neurinoma or schwannoma Accounts for 1/3 of the spine tumors Often originates from the dorsal root of the spine Usually arises from proliferating nerve fibers, Schwann cells and fibroblasts Often appears at the lower thoracic segment and the thoracolumbar junction Peak incidence: between 4th and 5th decade | Gautier-Smith (1967), Borenstein & Wiesel (1989), Conti et al (2004) |
Paget’s disease | A chronic metabolically active bone disease, characterized by thickening and deformation of the disturbed bone Often caused by hyperactive osteoclasts and osteoblasts Mainly affects flat bones and the ends of the long bones Approximately 45% of patients with this disease have thoracic spine involvement Affects around 3% of the population over 40 years of age Slightly predominant in males Overall prevalence: 3–3.7% | Altman et al (1987), Dell’Atti et al (2007) |
Tuberculosis (TB) of the spine | Usually involves the thoracolumbar region, particularly the lower thoracic and upper lumbar spines May cause anterior and sometimes lateral wedging of the spine May compromise the spinal cord extrinsically and intrinsically and may produce angular kyphotic or scoliotic deformities Accounts for about 50% of all cases of musculoskeletal TB Occurs in less than 1% of patients with TB | Turgut (2001), McRae (2010), Garg & Somvanshi (2011) |
Table 6.2
Common disorders of the thoracic spine
Thoracic spine examination
Medical history
Taking a detailed medical history of the patient is essential for the thoracic spine examination. In most cases, the narrative provided by the patient helps determine the red flags and facilitate the physical examination. The examiner must approach the patient in a friendly and respectful manner. They should collect the necessary information in a logical format and must listen to the patient’s responses very carefully. Apart from questioning about pain, swelling, numbness, tingling or any other issues over the thoracic region, they must inquire about the onset of the problem, behavior since onset, symptom pattern, and exacerbating and relieving factors.
Red flags
Red flags are used to provide clues to the existence of serious spinal pathology in patients with back problems (Honet & Ellenberg 2003). While questioning the patient, the examiner must look out for the presence of the red flags listed in Table 6.3 in their narrative. The screening process should begin with a detailed medical history and the use of a medical screening form.
Physical examination
After taking a detailed medical history of the patient, the clinician will have sufficient information to make tentative decisions about certain aspects of the case. Based on the findings from the initial interview, the clinician should then proceed to the physical examination. This involves a variety of observations and movements, so that the clinician can confirm initial findings, fully explore the nature and extent of the problem, and make judgments.
Condition | Signs and symptoms |
Spinal tumors | Over 50 years of age Past history of cancer Unintentional loss of weight, about 10 kg within 6 months Constant, severe and progressive back pain at night Pain lasting for more than a month No improvement after a month of conventional treatment |
Spinal infection | Over 50 years of age Recent bacterial infection such as respiratory, urinary tract or skin infection, tuberculosis History of intravenous drug abuse Persistent fever or systemic illness |
Fracture | Over 70 years of age Recent history of major trauma Prolonged use of corticosteroids History of osteoporosis |
Inflammatory arthropathy | Gradual onset: less than 40 years of age Family history Morning stiffness > 1 hour Persisting limitation of movement Involvement of peripheral joint Iritis, colitis, skin rashes or urethral discharge |
Vascular/neurological | Excessive dizziness Blackouts or falls Positive cranial nerve signs |
Table 6.3
Red flags for serious pathology in patients with thoracic spine pain
Data from Nachemson & Vingard (2000), Ombregt (2003), McKenzie & May (2006)
Observation
The physical examination process should start with a careful observation of the patient’s posture. Posture is best observed when the patient is unaware that the clinician is doing so, such as during the history taking. The clinician should note how the patient sits and stands. When the patient is standing, it should be noted whether the thoracic curvature appears regular or increased. While the patient is seated unsupported on a treatment table or examination couch, the clinician should note the curve of the spine. Obliteration of an abnormal curve during unsupported sitting suggests presence of scoliosis. It also suggests that scoliosis is mobile and may be secondary to shortening of a leg.
Movement patterns
Movements in flexion, extension and rotation should be examined in erect sitting. The clinician should initially perform the single movements to check the patient’s ability to move, and then repeated movements to determine the range and quality of movement and pain response to movement. The symptoms and mechanical responses should be noted carefully. The clinician should instruct the patient to repeat the movements that eliminate or reduce symptoms, and temporarily avoid movements that peripheralize or increase symptoms. Any deviations or discrepancies between sides must be recorded properly.
Special tests
See Table 6.4.
Test | Procedure | Positive sign | Interpretation |
Slump test | The patient sits on the edge of a treatment table, with legs supported, hands behind the back and hips in neutral. The examiner instructs the patient to slump forward at full thoracic and lumbar flex. The patient flexes the neck by placing the chin on the chest and the examiner maintains overpressure. The patient actively extends one knee as much as possible and the examiner then dorsiflexes the ankle. | Reproduction of symptoms in back and radicular symptoms | Increased tension in dura or meninges neural tissue sensitivity |
Brudzinski’s sign | The patient lies in the supine position. One of the examiner’s hands is behind the patient’s head and the other hand is on the patient’s chest. The examiner then passively flexes the patient’s neck by pulling the head to the chest, while restraining the body from rising. | Reproduction of pain in the back, and the patient involuntarily flexes the knees and hips to relieve the back pain | Dural or meningeal irritation Nerve root involvement |
Beevor’s sign | The patient lies in supine position and crosses the arms in front of the chest. The examiner then asks the patient to raise the trunk slightly off the couch and carefully observes the umbilicus. | Movement in a cranial or caudal direction or to the side | Denervation of the contralateral muscles |
