Definition

Thoracic strain or sprain refers to the acute or subacute onset of pain in the region of the thoracic spine due to soft tissue injury, including muscles, ligaments, tendons, and fascia, of an otherwise normal back. Sprain relates to injury in ligament fibers without total rupture, whereas strain is an overstretching or overexertion of some part of the musculature [1]. Because the thoracic cage is unified by the overlying fascia, thoracic sprain or strain can translate into pain throughout the thoracic spine.

Epidemiology

Although the scientific literature on musculoskeletal pain in the cervical and lumbar spine is abundant, similar information about the thoracic region is sparse because of its lower prevalence [2]. The lifetime prevalence in the general population of having a musculoskeletal complaint in the thoracic spine is 17% in contrast to 57% in the low back and 40% in the neck [3]. Therefore observation and characterization of such lesions are minimal, subsequently limiting the potential to improve treatment methods for thoracic sprain and strain disorders. Moreover, pain felt in the thoracic spine is often referred from the cervical spine, mistakenly giving the impression that the incidence is higher [4].

Thoracic strain or sprain may be the indirect result of disc lesions, which have been reported to be evenly distributed in incidence between the sexes and are most common in patients from the fourth to sixth decades of life [5]. Muscles adjacent to the injured disc tend to become tight in response to the local inflammatory process, which may jeopardize the local muscle equilibrium, possibly leading to ligament strains and muscle sprains in the thoracic region. Other structures that may lead to strain or sprain in the mid back due to the same inflammatory rationale are the thoracic facet joints and the nerve roots [6].

As with most nonspecific mechanical disorders of the cervical and lumbar regions, the natural history of the majority of patients with nonspecific thoracic strain or sprain is resolution within 1 to 6 months [7].

Mechanisms

The thoracic spine is considered to be the least mobile area of the vertebral column secondary to the length of the transverse processes, the presence of costovertebral joints, the decrease in disc height compared with the lumbar spine, and the presence of the rib cage. Movements that occur in the thoracic spine include rotation with flexion or extension.

Thoracic sprain and strain injuries can occur in all age groups, but there is an increased prevalence among patients of working age [8]. Intrinsic mechanisms include bone disease as well as alteration of normal spine or upper extremity biomechanics. This includes cervical or thoracic deformity from neuromuscular or spinal disease as well as shoulder or scapular dysfunction. The most common intrinsic cause of thoracic strain, however, is poor posture or excessive sitting. Poor posture may be related to development of Scheuermann disease in the young and osteoporosis in the elderly that leads to kyphosis and compression deformities seen in those patients.

Poor posture is often manifested as excessive protraction or drooping of the neck and shoulders as well as decreased lumbar lordosis or “flat back.” With the classic “slouched position” encountered in children and adolescents and often carried on through adulthood, there is excessive flexion of the thoracic spine with a decrease in rotation and extension.

Postural alterations promote increased thoracic kyphosis, resulting in the “flexed posture.” Excessive flexion results in excessive strain on the “core,” including the small intrinsic muscles of the spine, the long paraspinal muscles, and the abdominal and rib cage muscles. Excessive flexion can increase the risk of rib stress fractures as well as costovertebral joint irritation. This can cause referral of pain to the chest wall with subsequent development of trigger points in the erector spinae, levator scapulae, rhomboids, trapezius, and latissimus dorsi. Poor motion in extension and rotation can place an increased load on nearby structures, such as the lumbar or cervical spine and shoulders.

Extrinsic or environmental mechanisms include repetitive strain, trauma, and obesity. Risk factors include occupational and recreational activities characterized by repetitive motions, such as lifting, twisting, and bending. Occupations requiring manual labor or extended periods in a sitting position are predisposed to a higher incidence of such disorders [9]. Traumatic causes include falls, violence, and accidents leading to vertebral fractures, chest wall contusions, or flail chest.

Symptoms

Patients typically report pain in the mid back, which may be related to upper extremity or neck movements. Symptoms may be exacerbated by deep breathing, coughing, rotation of the thoracic spine, or prolonged standing or sitting. The pain can be generalized in the mid back area or focal. If it is focal, it is usually described as a “knot,” which is deep and aching. It may radiate to the anterior chest wall, abdomen, upper limb, cervical spine, or lumbosacral spine and may be accentuated with movement of the upper extremity or neck. As described by McKenzie [4], the location of pain in mechanical disorders of the thoracic spine is either central (symmetric) or unilateral (asymmetric).

Other symptoms include muscle spasm, tightness, and stiffness as well as pain or decreased range of motion in the mid back, low back, neck, or shoulder.

Physical Examination

The essential finding in the physical examination of thoracic sprain or strain is thoracic muscle spasm with normal neurologic examination findings. Pain may be exacerbated when the patient lifts the arms overhead, extends backward, or rotates. Rib motion may be restricted and may be assessed by examining excursion of the chest wall. This is accomplished by laying hands on the upper and lower chest wall and looking for symmetry and rhythm of movement. The upper ribs usually move in a bucket-handle motion, whereas the lower ribs move in a pump-handle motion. Restriction of specific ribs can be assessed by examining individual rib movements with respiration.

The position of comfort is usually flexion, but this is the position that should be avoided. Sensation and reflex examination findings should be normal. A finding of lower extremity weakness or neurologic deficit on physical examination suggests an alternative diagnosis and may warrant further investigation [10].

As the thoracic cage and spine are the anchors for the upper limbs, the thoracic spine influences and is influenced by active and resisted movement of the extremities, cranium, and lumbar and cervical spine [11]. Therefore, a careful spinal and shoulder examination is essential to rule out restrictive movements, obvious deformity, soft tissue asymmetry, and skin changes (that may be seen in infection or tumor). Detailed examination of other organ systems is important because thoracic pain can be referred.

Examination includes static and dynamic assessment of posture. The patient should be observed in relaxed stance with the shirt removed. Viewing is from the posterior, lateral, and anterior perspectives, and deviations from an ideal posture are noted [11]. With dynamic assessment, it is important to provoke the patient’s symptoms by moving and stressing the structures from which pain is thought to originate.

In addition, the presence of deformities and the site of pain and tenderness are noted. Pain is often felt between the scapulae, around the lower border of the scapula, and centrally in the area between T1 and T7. Much of the pain felt in the thoracic area, however, has been shown to originate in the cervical spine. Pain in the region above an imaginary line drawn between the inferior borders of the scapulae is most likely secondary to the cervical region, mainly lower cervical facet joints [12].

Functional Limitations

Functional limitations include difficulty with bending, lifting, and overhead activities, such as throwing and reaching. These limitations affect both active and sedentary workers. Activities of daily living, such as upper extremity bathing and dressing, might be affected. General mobility may be impaired. As most sports-related or leisure activities involve use of the upper extremity, extension, or rotation of the thorax, athletic participation and functional capacity may be limited as well.

Diagnostic Studies

Thoracic sprain and strain injuries are typically diagnosed on the basis of the history and physical examination. No tests are usually necessary during the first 4 weeks of symptoms if the injury is nontraumatic. If there is suspicion of tumor (night pain, constitutional symptoms), infection (fever, chills, malaise), or fracture (focal tenderness with history of trauma or fall), earlier and more complete investigation is warranted.

Plain films are indicated as an initial image diagnostic approach if the injury is associated with recent trauma or malignant disease. Magnetic resonance imaging is the study of choice in considering thoracic malignant neoplasia and osteoporotic compression fracture or when the patient has unilateral localized thoracic pain with sensory-motor deficits to rule out a thoracic disc herniation with consequent radiculopathy [13]. A computed tomographic scan or triple-phase bone scan can identify bone abnormalities if magnetic resonance imaging is contraindicated. Magnetic resonance imaging, however, can detect abnormalities unrelated to the patient’s symptoms because many people who do not have pain have abnormal imaging findings [14]. This fact emphasizes the importance of a meticulous clinical evaluation of patients with thoracic pain.

The initial treatment of a thoracic sprain or strain injury generally involves the use of cold packs to decrease pain and edema during the first 48 hours after the injury. Thereafter, the application of moist heat to reduce pain and muscle spasm is indicated. Bed rest for up to 48 hours may be beneficial, but prolonged bed rest is discouraged because it can lead to muscle weakness. Relative rest by avoidance of activities that exacerbate pain is preferable to complete bed rest. Temporary use of a rib binder or elastic wrap may reduce pain as well as increase activity tolerance and mobility. A short course of nonsteroidal anti-inflammatory drugs, acetaminophen, muscle relaxants, or topical anesthetics such as Lidoderm patches may be beneficial. Narcotics are generally not necessary.

Rehabilitation

Most acute thoracic sprain or strain injuries will heal spontaneously with rest and physical modalities used at home, such as ice, heating pad, and massage. Body mechanics and postural training are important aspects of the rehabilitation program for thoracic sprain or strain [15,16]. A focus on correct posture at work, at leisure, and while driving is important. In the car, patients can use a lumbar roll to promote proper posture; at work, patients are advised to sit upright at the computer in an adjustable, comfortable chair with an adequate monitor adjustment. The monitor should be adjusted to be aligned with the keyboard and in a height that aligns the first row of text with eye level. Finally, the correct depth should be achieved in a way that the user does not need to lean forward to comfortably read [17]. Other workplace modifications include forearm seat rests to support the arms, foot rests, and the use of a telephone earpiece or headset to prevent neck and upper thoracic strain.

For patients with abnormally flexed or slouched posture, household modifications can be made that might help encourage extension and subsequently decrease pain. These include pillows or lumbar rolls on chairs and replacement of sagging mattresses with firm bedding. Also, use of paper plates and lightweight cookware in the kitchen and reassignment of objects in overhead cabinets to areas that are more accessible can help if lifting or reaching is painful.

If pain persists beyond a couple of weeks, physical therapy may be indicated. In general, physical therapy will apply movements that centralize, reduce, or diminish the patient’s symptoms while discouraging movements that peripheralize or increase the patient’s symptoms [4]. In most cases, an active approach that encourages stretching and strengthening exercises is preferred to a more passive approach. To correct sitting posture, patients are advised to continue to use the lumbar roll in all sitting environments. To correct standing posture, patients are shown how to normalize lumbar curvature and to move the lower part of the spine backward while at the same time moving the upper spine forward, raising the chest and retracting the head and neck. To correct lying posture, patients should use a firm mattress as previously indicated. In the case of patients who experience more pain in the thoracic spine when lying in bed, this advice often leads to worsening of the symptoms rather than a resolution. In these patients, advice should be given to deliberately sag the mattress by placing pillows under each end of the mattress so that it becomes dished. In this manner, the thoracic kyphosis is not forced into the extended range in lying supine, and the removal of this stress allows a comfortable night’s sleep. Long-term goals, however, still include improvement in extension range of motion [4].

After a formal physical therapy program is completed, a home exercise or gym regimen is essential and should be prescribed and individualized for all patients to maintain gains made during physical therapy. Exercises at home are aimed at improvement in flexibility of the thoracic spine and may include extension in lying, standing, and sitting performed six to eight times throughout the day. In addition, alternating arm and leg lifts and active trunk extension in the prone position should be performed. Finally, regular stretching to improve extension and rotation with trigger pointing can decrease muscle tension over the affected muscles. A thoracic wedge, which is designed to increase extension range of motion, can be used. The wedge is a hard piece of molded plastic or rubber with a wedge cut out to accommodate the spine. The patient lies on the ground with the wedge placed in between the shoulder blades. The patient is instructed to arch over it. Alternatively, two tennis balls can be taped together for the same effect. These exercises can be done before regular stretching to increase excursion. Regular massage therapy can maintain flexibility and prevent tightening from more regular exercise.

At the gym, progressive dynamic movements such as rowing, latissimus pull-downs, pull-ups, and an abdominal crunch strengthening program should be emphasized. Instruction in proper positioning and technique should be provided to prevent further injury. Use of a “physio-ball” at home or at the gym can facilitate trunk extension as well as abdominal stretching and strengthening to increase overall conditioning of the thoracic cage and core musculature. This can be done in conjunction with use of Thera-Bands with progressive resistance to facilitate stretching of the arms and shoulders with mild strengthening of the shoulder, arm, and core muscles. Finally, a pool program can be prescribed. Swimming strokes such as the crawl, backstroke, and butterfly emphasize extension and can be very useful to prevent or to correct a flexion bias. With the crawl, patients are instructed to breathe on both sides to prevent unilateral strain in the neck and upper thoracic spine.

Procedures

Trigger point injections may help reduce focal pain caused by taut bands of muscle, allowing the patient to exercise to restore range of motion, to correct postural imbalance, and to increase strength and balance of the dysfunctional segment [18]. Acupuncture can be used for local as well as for systemic treatment. Finally, botulinum toxin type A (Botox) has been used for specific muscles, including rhomboids, trapezius, levator scapulae, and serratus, that often contribute to thoracic strain and sprain.

Although there are no studies specifically looking at the use of botulinum toxin type A for treatment of thoracic strain, there are studies that looked at treatment of regional myofascial pain disorders. One study showed effective pain relief for generalized myofascial pain syndrome [19]. In another study, there was no statistically significant improvement in pain with direct trigger point injections of patients with cervicothoracic myofascial pain syndrome [20]. A recent comprehensive review found inconclusive evidence on the use of botulinum toxin type A for muscle treatment, although some encouraging data are available [21].

Another possible treatment of myofascial pain syndrome that can be applied in thoracic sprain or strain cases is extracorporeal shock wave therapy. This may be an effective alternative to needling or medication infusion [22].

Surgery

Surgery is not usually indicated unless focal disc herniation with neurologic abnormalities such as radiculopathy (see Chapter 43) has occurred or there is instability of particular spinal segments from fracture or dislocation.

Potential Disease Complications

Thoracic sprain and strain injuries can occasionally develop into myofascial pain syndromes.

Potential Treatment Complications

Possible complications include gastrointestinal side effects from nonsteroidal anti-inflammatory drugs. Other possible complications include somnolence or confusion from muscle relaxants; addiction from narcotics; bleeding, infection, postinjection soreness, and pneumothorax from trigger point injections; excessive weakness and development of antibodies from botulinum toxin; and temporary post-treatment exacerbation of pain from manual medicine or extracorporeal shock wave therapy [23].