Posttraumatic Deformity

A. Karim Ahmed, Randall J. Hlubek, and Nicholas Theodore

Abstract

The thoracic spine is particularly susceptible to ischemia and life-threatening complications after traumatic injury because of its poor collateralization of vasculature and its proximity to vital structures. Traumatic injuries of the thoracic spine are classified as flexion, distraction, or torsional injuries. The most common presenting symptoms of posttraumatic deformity are pain and neurological deficit. An assessment of focal deformity, as well as global balance, is critical in these patients. Surgical management for posttraumatic deformity may be indicated if the patient has increasing back pain, increasing neurological deficit, instability, and severe or progressive deformity.

Keywords: deformity, ischemia, kyphosis, laminectomy, neurological deficit, thoracic spine, trauma

Clinical Pearls

• Imaging for posttraumatic deformity is multimodal and should include an assessment of osseous structures, interosseous spaces, soft tissue ligamentous structures, neural element compression, spinal instability, global balance parameters, and flexibility of the deformity.

• Surgical indications are increasing back pain, increasing neurological deficit, instability, and severe or progressive deformity.

• Surgical approaches for the treatment for posttraumatic deformity include an anterior approach, a posterior approach, or a combination of the two.

• The thoracolumbar junction serves as a transition zone between the semirigid thoracic spine and the mobile lumbar spine, requiring special consideration to prevent aberrant motion and iatrogenic deformity.

• Osteotomies may be necessary for a patient with rigid deformities including Smith–Petersen osteotomy, pedicle subtraction osteotomy, or vertebral column resection, listed by increasing angle of correction.

11.1 Thoracic Spinal Anatomy

The thoracic spine is relatively immobile and does not impart significant range of motion during activity. The 12 thoracic spine segments are caudal to the cervical spine. The thoracic vertebrae have vertically oriented articulating facets that connect with adjacent vertebrae. The posterolateral surface of the vertebral body in the thoracic spine has two demifacets. The cranial demifacet articulates with the head of the corresponding numbered rib, and the caudal demifacet articulates with the head of the rib below. An additional facet on the lateral aspect of the transverse process articulates with the tubercle of the rib; T1, T11, and T12 are exceptions to this rule. T1 has a single facet that articulates with the head of the first rib and an inferior demifacet that articulates with the head of the second rib. T11 and T12 do not contain costal facets on their transverse processes, but they do contain singular facets on their pedicles that articulate with the 11th and 12th ribs, respectively.¹^,²

The anterior and posterior aspects of the vertebral bodies and discs are enclosed by the anterior and posterior longitudinal ligaments. The ligamentum flavum forms the posterior aspect of the central canal, connecting adjacent laminae. The interspinous ligament travels in between the spinous processes, draped superficially by the supraspinous ligament.¹^,²^,³

The intervertebral discs between the vertebral bodies are composed of an outer annulus fibrosis and an inner nucleus pulposus. Composed primarily of type I collagen fibers, the annulus fibrosis is the fibrocartilaginous portion that resists motion and restricts the nucleus pulposus. The nucleus pulposus, as the primary shock absorber, is abundant in proteoglycan for water retention. The high water content of the nucleus pulposus creates hydrostatic pressure that resists compressive forces on the spinal column. Compared to the intervertebral discs in the cervical or lumbar spine, those in the thoracic spine are relatively thin and narrow, maintaining the immobility of this region.⁴^,⁵

The blood supply to the spinal cord is composed of two systems: the central system and the peripheral system. The central system, arising from the anterior spinal artery, supplies the anterior two-thirds of the spinal cord, which consists of the anterior gray matter, the anterior portion of the posterior gray matter, the anterior portion of the posterior white columns, the inner half of the anterior and lateral white columns, and the base of the posterior white columns. The peripheral system, arising from the posterior spinal arteries and pial arterial plexus, supplies the outer portion of the anterior and lateral white columns and the remainder of the posterior gray matter and posterior white columns.⁶^,⁷^,⁸ In the thoracic spine, posterior intercostal arteries from the aorta and subclavian artery give rise to segmental arteries. Branches of the segmental spinal arteries (the anterior and posterior radicular arteries) supply the anterior and posterior nerve roots. The segmental spinal arteries further branch into radiculomedullary arteries, which contribute to the anterior spinal artery and radiculopial arteries, which contribute to the posterior spinal arteries and pial network.⁹ The largest radiculomedullary artery, arising around T9 to T10, is the artery of Adamkiewicz. Compared to the cervical or lumbar spinal cord, the thoracic cord has a particularly inadequate collateralization of vasculature and is especially susceptible to ischemia.⁹^,¹⁰

The thoracic spine innervates somatic muscles in the chest and abdomen below T1. Of note, the only preganglionic sympathetic neurons originate from T1 to L2, in the lateral horns of the spinal gray matter. Central (first-order) neurons from the hypothalamus synapse at C8-T2, at the ciliospinal center of Budge. Preganglionic (second-order) neurons exit the spinal cord and synapse at the superior cervical ganglion.

Splanchnic nerves arise from the sympathetic trunk and contain efferent preganglionic sympathetic and visceral sensory afferent nerve fibers. The thoracic splanchnic nerves are from T1 to T4, the greater splanchnic nerves are from T5 to T9, the lesser splanchnic nerves are from T9 to T11, and the least splanchnic nerve is T12; however, there is variation regarding the spinal nerve that contributes to each splanchnic nerve.¹^,²

Trauma to the thoracic spine can be potentially devastating because of the close proximity of many vital structures. The sternal angle (i.e., the angle of Louis), at the level of T4 divides the superior and inferior mediastinum. Additionally, the carina of the trachea and the inner concavity of the aortic arch are located at T4. The inferior vena cava, esophagus, and aorta pass through the diaphragm at the level of T8, T10, and T12, respectively—each representing a potential site of injury.

11.2 Mechanisms of Injury

The thoracolumbar junction, at the inflection point of T12-L1, is the most frequent site of spine fractures, comprising about 64% of all spinal column fractures.¹¹ Traumatic fractures of the thoracic spine are due primarily to high-energy impact, most commonly motor vehicle collisions and falls from a height.¹¹^,¹²^,¹³^,¹⁴^,¹⁵ Posttraumatic deformity is a late complication of spinal column fractures. Traumatic thoracic spine fractures are best described using the AOSpine classification system,¹⁶^,¹⁷ which is based on the three resistive forces of the spine (i.e., flexion, distraction, and torsion)¹⁸ and which replaces the previous Denis classification.¹⁹

11.2.1 Flexion Injuries (Type A)

The flexion fracture pattern encompasses injuries due to vertebral body axial loading. Compression fractures (type A1) represent the most common spinal fracture. In type A1 injuries, the anterior column is the first to fail; the resulting fracture is known as a wedge fracture. Posterior element involvement follows, with greater compressive force. Subgroups of the type A1 injury, in increasing severity, include endplate impaction (A1.1), wedge fracture (A1.2), and vertebral body collapse (A1.3).

Type A2 injuries are split fractures of the vertebral body. These consist of a sagittal split (A2.1), a coronal split (A2.2), and a pincer fracture (A2.3). Pincer fractures often contain intervertebral disc material impacted within the vertebral body defect, leading to possible pseudarthrosis.¹⁶^,¹⁷^,²⁰

The most severe compression injury is a burst fracture (type A3), which may include fragment retropulsion into the spinal canal. Subtypes of burst fractures are classified by increasing severity as incomplete (A3.1), complete (A3.2), or burst split fractures (A3.3).

11.2.2 Distraction Injuries (Type B)

Type B injuries are primarily due to a failure of the posterior column. The posterior ligamentous complex, often referred to as the tension band, plays a critical role in spinal column stabilization. The posterior ligamentous complex, which resists distraction, consists of the supraspinous ligament, interspinous ligaments, articular facet capsules, and ligamentum flavum.¹²^,¹⁶^,¹⁷^,²¹

Type B1 injuries are due to flexion–distraction and are predominantly posterior ligamentous injuries. Posterior disruption with predominantly osseous involvement is classified as a type B2 injury, also known as a Chance or seat belt fracture. However, a hyperextension-shear injury, denoted as a type B3 injury, results in a combined anterior column disruption through the disc.

11.2.3 Torsional Injuries (Type C)

Type C injuries are attributed to axial rotation and are characterized by dual-column involvement and rotational displacement. Type C injuries may be present concomitantly with other fracture patterns such as a type A fracture with rotation (C1), a type B fracture with rotation (C2), or a rotation-shear injury (C3). Type C injuries have the potential for translational displacement and have the greatest association with posttraumatic neurological deficits.¹⁶^,¹⁷

In accordance with the AOSpine classification,¹⁶^,¹⁷ the increasing severity of injury is indicated by type (i.e., A–C) and respective subtype (e.g., A1.1–A1.3). However, with respect to severity, a comparison cannot be made between subtypes of different groups (e.g., B1.3 vs. C1.1). The AO classification system indicates severity of bony involvement, ligamentous involvement, neurological deficit, and mechanical instability.

Most posttraumatic deformities occur as a direct result of a traumatic insult, but they may also be the result of treatment. Kyphosis is the most common posttraumatic deformity of the thoracic spine. However, injuries such as lateral compression fractures or torsional injuries may lead to coronal deformity and should be carefully evaluated.

Injuries affecting the anterior, middle, and posterior columns are more likely to result in instability. As such, a stable compression fracture confined to the anterior column with minimal focal kyphosis (< 20 degrees) is unlikely to progress and will be compensated to maintain sagittal alignment. However, it should be noted that compensation from adjacent levels is biomechanically unfavorable and accelerates degenerative changes. Injuries with a focal kyphosis greater than 20 degrees may indicate posterior ligamentous involvement from a distraction injury, and they have a significantly greater chance of progressing to posttraumatic deformity.²²^,²³^,²⁴ The sagittal index, as will be described later in this chapter, is a useful tool for guiding the management of posttraumatic deformity. An injury that affects all columns, such as a complete burst fracture, has a greater likelihood of progression. Moreover, the potential for posttraumatic deformity is exacerbated with lower thoracic injury to the thoracolumbar junction, which is devoid of rib cage support.²²^,²³^,²⁴^,²⁵^,²⁶

Posttraumatic deformity that occurs after surgical treatment may be caused by pseudarthrosis, hardware failure, short fusions, and iatrogenic instability. Pseudarthrosis, or nonunion, may be due to various factors such as deep infections and inadequate bone mineralization, resulting in progressive deformity and adjacent segment instability.²⁷ Hardware failure is a potential risk for any patient undergoing instrumented surgery. Young’s modulus (the modulus of elasticity) is a measure of the resistance, or stiffness, of a material under tension and is a fixed property equal to the ratio of stress over strain. For a given stress, or force, a material has a finite capacity to deform; this capacity is defined as strain. Hardware failure occurs when the force placed on either the implanted hardware or the bone exceeds the material’s capacity for strain. Such failure may include hardware migration, rod fracture, screw fracture, and screw pullout, often necessitating larger surgical revisions.²⁸^,²⁹ Both laminectomy and short fusion constructs (less than five levels), particularly at the thoracolumbar junction, have been associated with progressive posttraumatic deformity and are generally not advised.²²^,²³^,²⁴^,³⁰

Rarely, neuropathic spinal arthropathy (Charcot’s spine) or vertebral body osteonecrosis (Kümmell’s disease) may occur after trauma. Charcot’s spinal arthropathy may occur after spinal cord injury and is characterized by a sequence of sensory feedback loss, atypical joint motion, microtrauma, bone resorption, joint destruction, and adjacent segment pseudarthrosis.³¹^,³²^,³³^,³⁴ In Kümmell’s disease, avascular osteonecrosis and nonunion lead to vertebral body collapse and progressive deformity.³⁵^,³⁶

Although most traumatic fractures of the thoracic spine occur because of high-energy impact, patients with poor bone quality may sustain traumatic injury and progress more easily to posttraumatic deformity or hardware failure. Conditions associated with poor bone quality include osteoporosis, ankylosing spondylitis, osteogenesis imperfecta, and other endocrine disorders.²²^,²³^,²⁴^,³⁷ Osteoporosis is the condition of having bone mineral density 2.5 standard deviations or more below that of young adults (t-score ≤ −2.5); patients with osteoporosis are at high risk for spinal compression fractures.³⁸ A single compression fracture in a patient with osteoporosis substantially increases the risk for subsequent compression fractures, propagating kyphosis and sagittal imbalance.³⁹^,⁴⁰

Patients with ankylosing spondylitis require special attention after trauma because of the altered spinal biomechanics present in this population. Bridging ossification leads to a rigid kyphotic deformity and atypical fracture patterns. Most often caused by extension–distraction injuries, these fractures are transverse through the anterior column of ossified discs or vertebral bodies. The fractures result in substantial instability between two adjacent segments and may lead to translational displacement and deformity.⁴¹^,⁴²

Pediatric patients with traumatic thoracic spine injury are a unique population due to their skeletal immaturity and growth potential. In children, ligament laxity and a large head size make trauma of the cervical spine more common than trauma of the thoracic spine. When injury of the pediatric thoracic spine does occur, it can result in posttraumatic kyphosis and paralytic scoliosis with rates as high as 64 and 96%, respectively.⁴³^,⁴⁴^,⁴⁵^,⁴⁶ Various mechanisms exist for posttraumatic spinal deformity in pediatric patients. Muscle spasticity from spinal cord injury, joint surface abnormality from misalignment, and asymmetric physeal closure can all facilitate the development of progressive deformity in children who sustain thoracic spine trauma.⁴⁷^,⁴⁸^,⁴⁹^,⁵⁰^,⁵¹^,⁵²

11.3 Clinical Features of Posttraumatic Deformity

In acute situations, the appropriate identification and management of thoracic spine trauma are essential. Traumatic injury to the upper thoracic cord (above T6) may result in life-threatening autonomic dysreflexia, neurogenic shock, or spinal shock. Poor collateralization makes the thoracic spine especially susceptible to ischemia. Mean arterial blood pressure elevation, decompression, and stabilization are critical components in acute management.⁸^,⁵³^,⁵⁴

After trauma, patients who develop a posttraumatic deformity may have a noticeable curvature with or without compensation. Although kyphosis is the most common posttraumatic deformity, lateral compression fractures or burst fractures may cause focal scoliosis and trunk shift in the coronal plane. Common symptoms of deformity include back pain, a loss in height, neurological deficit, and difficulty standing. Pain is the most common presenting symptom of patients with posttraumatic deformity, and a localized kyphotic deformity greater than or equal to 30 degrees has been shown to significantly increase the risk for chronic pain in that region.²⁴^,⁵⁵^,⁵⁶^,⁵⁷

Patients with posttraumatic deformity may also experience new or progressive neurological deficits. In a study by Malcolm et al⁵⁶ of 48 patients with posttraumatic deformity, 27% experienced increasing neurological deficit. New or worsening neurological deficits may be due to posttraumatic cystic myelopathy, spinal cord tethering, and progression of deformity, but they are most commonly due to posttraumatic syringomyelia. Posttraumatic syringomyelia comprises 25% of all diagnosed syringomyelia cases.⁵⁸^,⁵⁹^,⁶⁰ Syringomyelia may also be closely associated with the underlying deformity. In a study of 207 cases of traumatic paraplegia with fully healed fractures, Abel et al⁶¹ demonstrated that posttraumatic kyphosis greater than 15 degrees and canal stenosis greater than 25% doubled the likelihood of syringomyelia. Interestingly, there was significant correlation between the extent of spinal stenosis and the amount of deformity.

Severe posttraumatic deformity can also have an impact on the overall health of these patients. They may experience premature gastrointestinal satiety, difficulty breathing, or cardiac abnormalities secondary to compression of the abdomen and thoracic cavity.²²

11.4 Sagittal and Coronal Balance

A spinal deformity is an aberrant curvature of the spinal column that may be congenital, iatrogenic, idiopathic, degenerative, or traumatic. Nonetheless, it is necessary to define a few key terms relating to coronal and sagittal balance parameters when assessing spinal deformity. Each of these measurements is best appreciated using standing 36-inch cassette plain films.

11.4.1 C7 Plumb Line (C7PL)

On the lateral view, the C7 plumb line is a line drawn caudally from the C7 vertebrae to the sacrum. In normal sagittal alignment, the C7 plumb line should be within 2.5 cm of the posterior aspect on the sacral endplate—also known as the sagittal vertebral axis (SVA). An SVA value greater than 2.5 cm may indicate positive sagittal balance, whereas an SVA value less than 2.5 cm may indicate negative sagittal balance. However, these values should be considered along with other parameters, as the SVA becomes more positive as individuals age.⁶²

On the standing anteroposterior view, a line drawn caudally from the center of the C7 vertebrae should overlap a corresponding line drawn cephalad from the center of the sacral promontory. This is known as the central sacral vertical line. Trunk shift in the coronal plane may be suspected if these two lines do not overlap.⁶³^,⁶⁴

11.4.2 Cervical Lordosis

Cervical lordosis is the angle between the inferior endplate of C2 and the inferior endplate of C7. Lordosis of the cervical spine is typically 40 ± 9.7 degrees and is primarily determined by the T1 slope.³⁴^,⁶² The magnitude of cervical lordosis is highly variable and responds to changes in alignment in the thoracolumbar spine.

11.4.3 Thoracic Kyphosis

Thoracic kyphosis, measured from the superior endplate of the T5 vertebral body to the inferior endplate of the T12 vertebral body, is normally between 20 and 50 degrees. The degree of thoracic kyphosis is greatly influenced both by the position of C7 cephalad and by the extent of lumbar lordosis caudal.⁶⁵^,⁶⁶^,⁶⁷ Focal kyphosis of a single-level fracture is most appropriately measured as the angle formed by the superior endplate and the inferior endplate of the adjacent cephalad and caudal vertebra, respectively.²²^,²³^,²⁴

11.4.4 Lumbar Lordosis

Lumbar lordosis is the angle formed from the superior endplate of L1 and the superior endplate of S1, and it is typically 30 to 60 degrees. The ideal amount of lumbar lordosis is determined by the pelvic incidence and should be within 10 degrees of that value. In general, thoracic kyphosis and lumbar lordosis are proportional in order to maintain balance in the sagittal plane. As such, increasing lumbar lordosis is positively associated with an increase in thoracic kyphosis.⁶²^,⁶⁷^,⁶⁸^,⁶⁹

11.4.5 Pelvic Incidence

The pelvic incidence is measured with a line drawn from the midpoint of the femoral head to the center of the sacral endplate. A second line, drawn inferiorly and perpendicular to the sacral endplate, forms the angle of the pelvic incidence. Spinopelvic parameters dictate the attachment of the spinal column to the pelvis and are fundamental components of global deformity and spinal biomechanics.

As a general rule, the pelvic incidence should be within 10 degrees of the lumbar lordosis. It is influenced by multiple factors such as the sacral slope, pelvic tilt, and shape of the pelvis. The pelvic tilt, or rotation of the pelvis about the femoral heads, is the angle formed between a vertical line and a second line reaching the center of the sacral endplate, both originating from the midpoint of the femoral heads. Moreover, the sacral slope is the downward angle formed from the sacral endplate, relative to the horizontal. Although the pelvic tilt and sacral slope are influenced by posture, the sum of the two values yields the pelvic incidence and highlights both the associations among numerous spinal alignment parameters and the compensation that occurs to maintain upright posture and balance.⁶²^,⁷⁰^,⁷¹^,⁷²^,⁷³^,⁷⁴^,⁷⁵ Moreover, the vertebral loading forces that result from thoracic hyperkyphosis may be compensated for by an increase in lumbar lordosis or pelvic tilt, with the former achieving the more biomechanically favorable vertebral loading.⁶⁸

11.4.6 Sagittal Index

The sagittal index is a measure of segmental kyphotic deformity. It is calculated by subtracting the baseline values for contours of the spine from the kyphotic angle of the involved level. Instrumented arthrodesis is indicated for a sagittal index greater than 15 degrees.⁷⁶^,⁷⁷

11.4.7 Apex

In patients with coronal deformity, the apex is the disc or vertebra that is deviated farthest from the vertebral column.⁶³

11.4.8 Neutral Vertebra

Vertebral rotation in the axial plane often accompanies coronal deformity. Neutral vertebrae are those that are not rotated in the axial plane. They are characterized by clearly visible pedicles and a spinous process in the center of each vertebra.⁶³

11.4.9 Stable Vertebra

In coronal deformity, stable vertebrae are the most cephalad. They are bisected, or nearly bisected, by the central sacral vertical line.

11.4.10 End Vertebra

The end vertebrae in patients with coronal deformity are those that are the most tilted cranially and caudally that surround the curve.

11.4.11 Cobb’s Angle

The Cobb angle is the angle formed by the cranial and caudal end vertebrae.

11.5 Imaging

Imaging is the mainstay for diagnosing a posttraumatic deformity, and it will dictate clinical decision making. As described previously, standing 36-inch plain films are essential in evaluating sagittal deformity, coronal deformity, and global balance. Flexion–extension (anteroposterior) and bending radiographs (lateral) shed light on the flexibility of a deformity.²⁴^,⁷⁸^,⁷⁹^,⁸⁰

Computed tomography (CT) is unparalleled in the evaluation of bony structures, as well as of the interosseous spaces. After acute trauma, many patients undergo a CT scan of the chest, abdomen, and pelvis (CT/CAP, chest abdomen pelvis). In a study by Hauser et al,⁸¹ 215 patients with high-risk thoracolumbar spine trauma were evaluated using CT/CAP and thoracolumbar radiographs. The accuracy of CT compared to radiography for identifying acute thoracolumbar fractures was found to be 99 and 87%, respectively. Similarly, McAfee et al⁸² demonstrated that CT was the most sensitive imaging modality for the diagnosis of posterior element defects and unstable burst fractures.

Soft tissue structures and neural elements are best visualized by magnetic resonance imaging. Posttraumatic cystic myelopathy, spinal cord tethering, and syringomyelia are also best visualized on magnetic resonance imaging. Moreover, serial imaging can be used to monitor the progression of posttraumatic deformity.⁵⁸^,⁸³^,⁸⁴^,⁸⁵^,⁸⁶

11.6 Surgical Treatment

Surgery for posttraumatic deformity may be indicated for increasing back pain, increasing neurological deficit, instability, and severe or progressive deformity.²²^,²³^,²⁴ Patients with posttraumatic deformity may experience debilitating pain related to degeneration and compensation for global alignment. Results of studies on pain related to fixed sagittal imbalance and canal compromise have been promising, with most reports indicating that patients achieved clinically significant pain relief.⁸⁷^,⁸⁸^,⁸⁹^,⁹⁰^,⁹¹ However, patients with degenerative sagittal imbalance had less pain relief and more postoperative complications.⁹⁰^,⁹¹ Nonetheless, the pain level after surgery is difficult to predict and should be assessed along with other symptoms, the extent of surgery, and possible complications.

New or worsening neurological deficit, such as myelopathy and radiculopathy, after posttraumatic deformity is an indication for surgery. Surgery should be aimed both at decompression, often in the anterior column, and at stabilization. An anterior approach and a corpectomy can be used to address neurological deficits related to posttraumatic kyphosis. The anterior approach has demonstrated greater effectiveness than the posterolateral approach in improving neurological deficits, and it allows for anterior column reconstruction.²²^,²³^,²⁴^,⁶¹^,⁹²^,⁹³^,⁹⁴ While the anterior approach historically demonstrated efficacy for the treatment of thoracolumbar burst fractures, newer instrumentation and posterior techniques have made both approaches highly effective.⁹⁵^,⁹⁶^,⁹⁷^,⁹⁸ A meta-analysis comparing anterior and posterior approaches, consisting of seven clinical trials, found no differences in neurological recovery, return to work, complications, and Cobb’s angle between the two approaches. The anterior approach, however, was associated with increased operative duration, blood loss, and cost.⁹⁹ The decision of surgical approach should be taken on a case-by-case basis, with careful consideration of clinical characteristics and operative goals.⁹⁵^,⁹⁶^,⁹⁷^,⁹⁸^,⁹⁹

Surgical approaches for the treatment of posttraumatic deformity include anterior, posterior, or combined approaches, and they vary based on symptoms and the nature and extent of the deformity. The anterior approach may be useful for extensive decompression (i.e., retropulsed fragments in the canal), spinal mobilization, or anterior reconstruction.⁹⁵^,⁹⁶^,⁹⁷^,⁹⁸^,⁹⁹ Attempts at stabilization must consider iatrogenic instability and posterior element instability, potentially requiring a combined posterior instrumented fixation.²²^,²³^,²⁴^,⁵⁷^,⁹²^,⁹³^,⁹⁴

Osteotomies may be necessary in cases of rigid deformity and should be planned based on the amount and nature of correction. The Smith–Petersen osteotomy allows for a mean correction of 10 to 15 degrees through shortening of the posterior column.²²^,⁹⁷ Pedicle subtraction osteotomy allows 30 to 35 degrees of sagittal correction at a given level and avoids destabilization of the anterior column. Vertebral column resection is the most extensive procedure, and it involves the removal of one or more vertebral segments.¹⁰⁰^,¹⁰¹^,¹⁰²^,¹⁰³ Decisions about surgeries, including osteotomies, for rigid posttraumatic thoracic deformity are outlined well by Buchowski et al¹⁰³ and are based on sagittal balance or imbalance. For normal sagittal balance, smooth thoracic kyphosis may be best treated using the Smith–Petersen osteotomy, whereas sharp angular kyphosis may be best treated using pedicle subtraction osteotomy or vertebral column resection. For patients with global imbalance, both smooth and sharp angular kyphosis can be used based on the extent of imbalance. With smooth thoracic kyphosis, both minor sagittal imbalance (SVA < 2.5–5 cm) and major imbalance (SVA > 5 cm) can be treated by Smith–Petersen osteotomies. However, cases of anterior column fusion or sharp angular kyphosis, with sagittal deformity, may require a more extensive pedicle subtraction osteotomy or vertebral column resection. The posterior vertebral column resection and pedicle subtraction osteotomies are performed from a posterior approach and provide adequate deformity correction, in addition to canal decompression, in such cases. However, the benefits of these technically involved osteotomies should be weighed against risks of blood loss and iatrogenic neurological injury.¹⁰⁴^,¹⁰⁵

11.7 Case Illustration

A 30-year-old woman from Greece presented with progressive kyphosis, worsening neurological function, and a painful gibbus deformity at the thoracolumbar junction. She had sustained a fall 14 years previously that resulted in a T12 burst fracture. She was originally treated with posterior instrumentation consisting of a Luque rectangle. Upon presentation at our institute, she underwent a physical examination, which revealed a Brown–Séquard–type injury. Her strength was assessed as 1 to 2 of 5 in the proximal right lower extremity, and she had good sensation in the left lower extremity. Imaging demonstrated posttraumatic kyphosis at the thoracolumbar junction with spinal cord compression ( Fig. 11.1). Surgery was performed in three stages to prevent further neurological decline and to stabilize the spinal column. In stage 1, the Luque rectangle was removed, and pedicle screws were placed at T10, T11, L1, and L2 ( Fig. 11.2). Osteotomies were performed at the fracture site to allow for reduction of the deformity. In stage 2, a left-sided thoracotomy and a T12 corpectomy were performed to reduce the kyphotic deformity. Then an expandable titanium cage and plating were placed from T11 to L1 ( Fig. 11.3). In stage 3, rods were secured in the previously placed pedicle screws ( Fig. 11.4). Postoperative imaging demonstrated correction of the posttraumatic deformity ( Fig. 11.5). After surgery, the patient experienced no immediate change in neurological function and began working with the neurorehabilitation team.

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Apr 27, 2020 | Posted by admin in CARDIAC SURGERY | Comments Off

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