Thoracolumbar spine trauma classifications: evolution or more confusion

Transcription

1 Thoracolumbar spine trauma classifications: evolution or more confusion Poster No.: C-1713 Congress: ECR 2012 Type: Educational Exhibit Authors: J. P. Salazar, J. Halaburda Berni, C. Torrents, L. Casas; Barcelona/ES Keywords: Trauma, Diagnostic procedure, Decision analysis, MR, CT, Neuroradiology spine, Musculoskeletal spine DOI: /ecr2012/C-1713 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 31

2 Learning objectives To illustrate the variety of traumatic thoracolumbar spine injuries. To review and to compare features, advantages and disadvantages of the main classification systems of thoracolumbar trauma. Background Most spinal fractures occur in the thoracic or lumbar spine. Several classifications have been developed based on morphology, injury mechanism, spinal stability and risk of neurological lesion. Existing thoracolumbar trauma classifications with their publication year and number of categories are shown in Table 1 on page 3. Some of them are complex, inaccurate, not predictive or not validated. This has led to confusion among residents and radiologists creating lack of consensus between radiologists, clinicians and surgeons. The Thoracolumbar Injury Classification and Severity Score (TLICS) was recently developed and proposed to overcome these limitations; however, it has not been universally adopted. Spine trauma is a catastrophic event that causes high morbidity and mortality among young and elder population, in addition to the high financial and social cost for families and society. Its principal causes are motor vehicle accidents, falls, aggressions and sport activities; therefore, excluding, assessing and classifying thoracic and lumbar injuries are important roles of radiologists working in any hospital or emergency service. Anatomy CT scanning is the first choice imaging modality for patients in whom thoracolumbar fracture is suspected, thus the radiologist must be familiarized with some basic and fundamental thoracic and lumbar vertebrae anatomy on CT. This will give us a better understanding of the classification systems. As all we know from our basic anatomical knowledge, there are twelve thoracic (T1-T12) and five lumbar (L1-L5) vertebrae with the same number of intervertebral discs numbered in cephalo-caudal direction. In the thoracic region vertebral bodies and transverse processes articulate with ribs, while lumbar vertebrae are distinguished by a larger size and absence of costal facets. Spinous process increase in length while going downwards Page 2 of 31

3 from thoracic to lumbar, but undergo a progressive transition into horizontal position in the thoracolumbar junction. There is a normal anterior thoracic kyphotic angulation and lumbar lordosis in the sagittal plane. The principal parts of the thoracic and lumbar vertebrae on CT are show in Fig. 1 on page 4 and Fig. 2 on page 5. The vertebral foramen is formed by the posterior portion of the vertebral body, two pedicles and two laminae forming the posterior arch of the foramen. Transverse, spinous, superior articular and inferior articular processes project from the vertebral arch, working as muscle insertions or stabilization of the spine. Even though all vertebral parts share functions, vertebral bodies undergo most of the corporal weight and vertebral arches contain and protect the spinal cord and nerve roots. The conus medullaris lies within the vertebral foramen at the level of L1-L2, after this the cauda equina continues within the vertebral canal. Ligaments are fibrous connective tissue and they maintain bones and cartilages together providing stability during rest or movement and limiting from excessive displacement. The principal ligaments in the spine are the anterior longitudinal ligament, posterior longitudinal ligament, interspinous ligament, supraspinous ligaments, intertransverse ligaments and ligamentum flavum Fig. 3 on page 6. The posterior ligamentous complex or PLC is composed by interspinous ligament, supraspinous ligament and ligamentum flavum). They protect the spine and spinal cord from excessive flexion, rotation, translation and distraction. Images for this section: Page 3 of 31

4 Table 1: Existing Thoracolumbar Spine Trauma Classifications Page 4 of 31

5 Fig. 1: Thoracic vertebral bone anatomy Page 5 of 31

6 Fig. 2: Lumbar vertebral bone anatomy Fig. 3: Principal ligaments of the spine. Page 6 of 31

7 Imaging findings OR Procedure details Considering main thoracolumbar spine trauma classification and their categories it is clear that in daily practice radiologists use different terms or nomenclature to describe fractures and apply diverse categories combining classifications. We will describe the most widely used thoracolumbar spine trauma classification systems, so that the radiologist can rapidly identify and use them adapting to the classification system used by his or her team. Then we will compare their advantages and disadvantages. More than present a comprehensive review of thoracolumbar spine trauma we will highlight findings on CT that contribute to an adequate classification using the different systems. Preferentially, we will use the three column model proposed by Denis, the AO / Magerl classification based on morphological characteristics of the lesion and the TLICS that uses a point scale that combines imaging findings of CT or MRI and neurological status of the patient. Major categories of the principal thoracolumbar spine trauma classification are shown in Table 2 on page 12. Many classifications use mechanisms of injury to classify a fracture. The principal mechanisms of injury are shown in Fig. 4 on page 13. Boehler (1929): in this classification the author combined anatomical descriptions with injury mechanisms proposing five categories of injuries. Currently, the nomenclature created by Boehler is used to describe fractures even though it was designed for plain X-radiography. Its five categories are: Compression fractures, flexion-distraction Fig. 5 on page 14, injuries (anterior injury secondary to compression and posterior injury secondary to distraction), extension fractures, shear fractures, rotation injuries. Watson-Jones (1938): he was the first to consider that the major determinant of stability of the spine is the integrity of the posterior neural arch, which maintains spine structure avoiding dislocations. He described three injury types: simple wedge fracture Fig. 6 on page 14, comminuted fracture and fracture-dislocation. Nicoll (1949): the mechanical stability of the spine is determined by the vertebral body, the disc, the intervertebral joints and the interspinous ligament, considering the latter as the principal determinant of stability. Its categories are: anterior wedge fractures, lateral wedge fractures, fracture dislocation and neural arch fractures. Holdsworth (1963): he proposed that in accidents the spine is subjected to one of five types of violence: pure flexion, flexion rotation, extension, vertical compression or direct shearing force. In addition, the author introduced the column concept dividing the spine in anterior column (vertebral body and intervertebral disc) and posterior column Page 7 of 31

8 (facet joints and the posterior ligamentous complex). For this classification the principal factor determining stability is the integrity of the posterior ligamentous complex. The classification includes: anterior compression fractures, fracture dislocations, rotational fracture dislocations, extension injuries Fig. 7 on page 15, shear injuries and burst fractures. Kelly and Whitesides (1968): the authors redefined the two column concept of Holdsworth considering vertebral body as the anterior column and neural arch and posterior elements as the posterior column. They emphasized the importance of the posterior elements contributing to the stability of the weight bearing anterior column of the spine. A greater instability generates a greater severity of injury. In their classification the authors also divided stable injuries: anterior wedge, lateral wedge and stable burst; from unstable injuries: flexion-dislocation, flexion-rotation, unstable burst. Denis (1983): usingct imaging technology Denisredefined the two column concept describing a middle column, in addition to the anterior and posterior columns. For this author, the anterior column is formed by the anterior longitudinal ligament and the anterior part of the vertebral body. The middle column consists of the posterior part of the vertebral body, posterior longitudinal ligament and posterior annulus. The posterior column includes all structures posterior to the posterior longitudinal ligament which includes the osseous posterior elements and the posterior ligamentous complex Fig. 8 on page 17. This classification includes is summarized in Table 3 on page 16: Compression fractures: determined by failure of the anterior column under compression Fig. 6 on page 14 and Fig. 9 on page 19. Burst fractures: determined by failure of the anterior and middle columns with fracture of the vertebral body under axial loadfig. 10 on page 19 and Fig. 11 on page 19.There are five types of burst fractures expanding the concept exposed by Holdsworth and Kelly. Seat belt injuries: determined by failure of the posterior and middle column, under flexion-distraction forces Fig. 5 on page 14 and Fig. 12 on page 20 Fracture dislocations. Failure of the three columns Fig. 14 on page 22 and Fig. 15 on page 23 According to Denis spine stability was based on three columns instead of two, being the middle column the most important for structural stability. Denis highlighted the importance of neurological status and described three forms of instability by degrees. The first degree corresponds to isolated mechanical instability, second-degree includes injuries Page 8 of 31

9 with neurologic component but no mechanical instability and third degree refers to injuries with mechanical and neurologic instability. Denis also described subtypes for each classification which are shown in Table 3 on page 16 ; however, their understanding and using by radiologist is not as wide as for the main categories. Ferguson and Allen (1984): they proposed a classification based on the anterior and posterior elements, instead of the column concept described by Denis. In addition, they linked the type and pattern of fracture with de instrumentation required for its treatment. They proposed seven injury types: vertical compression, compression flexion, distraction flexion, lateral flexion, translation, torsional flexion and distractive extension. McAfee (1993): Based on CT imaging and a three column concept authors describe that there are three forces that can produce failure of the middle column: axial compression, axial distraction and translation. If the middle column is preserved it is unlikely that the spine fracture requires surgery. Authors simplified other classifications and described six injury patterns: wedge-compression fracture, stable burst, unstable burst, chance, flexion-distraction, translational shear. McCormack and Gaines (1994): More than a classification system McCormack and Gaines proposed a scale to predict risk of failure after instrumentation. It uses a scoring system from 1 to 3 to assess the amount of damaged vertebral body, the spread of fragments in the fracture sight and the level of sagittal plane deformity. A score greater than 7 is associated with failure. AO/Magerl (1994): This system is based on the AO (Arbeitsgemeinschaft fur Osteosynthesenfragen) classification used for extremity fractures. AO/Magerl proposes three principal mechanism of spinal injury: compression (type A), distraction (type B) and torsion (type C). Type C fractures are unstable injuries or those with multidirectional instability. Authors use a two column concept instead of three that proposed Denis. This is a very comprehensive classification progressively organized by damage and severity into three types (A, B and C) with three groups (A1, A2, A3), three subgroups (A1.1, A1.2 and A1.3) and three subdivisions (A1.1.1, A1.1.2 and A1.1.3) in each type. Table 4 on page 21. This classi#cation incorporates not only the mechanism of injury but also the fracture pattern, and it attempts to categorize every injury based on stability Even though it is a complete classification, the huge number of alternatives limits its use in clinical practice and generates confusion beyond the three main types. Despite widespread usage of the Page 9 of 31

10 AO classi#cation, it has lower inter-observer reliability and is less useful in therapeutic decision making and prognostic purposes. The types and groups of AO classification are: Type A (compression). A1: impaction fracture. Fig. 6 on page 14 and Fig. 9 on page 19 A2: split fracture. A3: burst fracture. Fig. 10 on page 19 and Fig. 16 on page 23 Type B (distraction) B1: posterior ligamentary lesion (subluxation). Fig. 12 on page 20 B2: posterior osseous lesion (spondyloslysis). Fig. 5 on page 14, Fig. 13 on page 21 and Fig. 17 on page 24 B3: anterior disc rupture. Type C (Rotation injury) C1: type A with rotation (anterior-posterior dislocation).fig. 15 on page 23 C2: type B with rotation (lateral shear). Fig. 18 on page 26 and Fig. 19 on page 27 C3: Rotational (rotational burst) TLICS - Thoracolumbar Injury Classification and Severity Score (2005): the Spine Trauma Study Group created TLICS trying to overcome previous classifications problems. It was proposed by experts from different countries who intended to formulate a system useful for identifying unstable fractures might require surgery and predict their outcome. It considers imaging findings and neurological assessment in a point system grading scale Table 5 on page 25 The three principal parameters that TLICS considers are: injury morphology, integrity of the PLC and neurological status, which are graded to calculate a final score. - Injury Morphology : Compression injuries (1 point) are defined by loss of height of the vertebral body or disruption through the vertebral end plate, including within this Page 10 of 31

11 mechanism traditional compression and burst fractures. Fig. 6 on page 14, Fig. 10 on page 19 Rotation/Translation injuries (3 points) are defined by horizontal displacement of one thoracolumbar vertebral body with respect to another, including within this mechanism unilateral or bilateral dislocations, facet fracture-dislocations, bilateral pedicle or pars fractures with vertebral subluxation. Rotational instability is best demonstrated by horizontal rotation of the spinous processes and pedicles Fig. 17 on page 24, Fig. 18 on page 26 and Fig. 19 on page 27 Distraction injuries (4 points) are defined by anatomic dissociation in the vertical axis, including hyperextension injuries with disruption of the anterior longitudinal ligament, fracture of the posterior elements with distraction Fig. 5 on page 14, Fig. 12 on page 20, Fig. 20 on page 27 - Neurologic status: Intact (0 points) Nerve Root injury (2 points) Spinal cord/ conus complete injury (2 points) Spinal cord/ conus incomplete injury (3 points) Cauda equina syndrome (3 points) - Posterior Ligamentous Complex integrity: Intact (0 points) Suspected / indeterminate (2 points) Disrupted (3 points) Assessment of the PLC can be established by plain radiography, CT scans and MRI. Main imaging findings are: - Widening of the interspinous space - Widening of facet joints - Empty facet joints - Facet subluxation - Dislocations of the spine Page 11 of 31

12 - Disruption of ligaments on MRI imaging. A score less than 4 indicates non-surgical treatment, while a score greater than 4 indicates the need of surgical treatment because of significant instability. A total score of 4 may be treated either surgically or non-surgically Table 5 on page 25. Nevertheless, due to its relatively recent publication, there is not enough evidence to back its performance. The mayority of studies have been undertaken by the same group who formulated it, making it necessary for other researchers to demonstrate its validity Images for this section: Page 12 of 31

13 Table 2: Thoracolumbar spine trauma classifications with their major categories Page 13 of 31

14 Fig. 4: Spine Injury Mechanims Fig. 5: Flexion distraction L2 injury Page 14 of 31

15 Fig. 6: Anterior wedge L3 fracture. Page 15 of 31

16 Fig. 7: T11-T12 Hiperextension injury. Page 16 of 31

17 Table 3: Denis classification Page 17 of 31

18 Fig. 8: Denis three column concept Page 18 of 31

19 Fig. 9: Anterior compression fracture Fig. 10: T12 and L4 Burst fractures. Page 19 of 31

20 Fig. 11: Burst fracture sagital MIP Page 20 of 31

21 Fig. 12: T6-T7 Seat belt injury Fig. 13: T12 Seat-belt injury (flexion distraction). Page 21 of 31

22 Table 4: AO/Magerl classification Page 22 of 31

23 Fig. 14: T5 fracture dislocation Fig. 15: T7-T8 Fracture dislocation Page 23 of 31

24 Fig. 16: T6-T7 Distraction fracture with posterior osseous lesion Page 24 of 31

25 Fig. 17: T5-T6 Rotational injury Page 25 of 31

26 Table 5: TLICS classification Page 26 of 31

27 Fig. 18: T3-T4 Flexion distraction injury with rotational component Fig. 19: T10-T11 Rotational injury with oblique fracture of the vertebra Page 27 of 31

28 Fig. 20: T1 Flexion distraction injury Page 28 of 31

29 Conclusion There are several classification systems for traumatic thoracolumbar injuries, each of them with advantages and disadvantages summarized in Table 6 on page 29. Radiologists should be able to recognize and use these systems to optimally communicate precise findings. However, in spite of multiple classifications, the challenge for the radiologist is to describe the anatomy and mechanics of the findings in a patient with thoracolumbar trauma. The role of the radiologist is to supply useful and pertinent information in the evaluation and treatment of the patient. It is necessary to carry out more studies in order to evaluate the new classifications that integrate CT and MRI information with the patient's clinical condition. Images for this section: Page 29 of 31

30 Table 6: Advantages and disadvantages of Thoracolumbar trauma classifications Page 30 of 31

31 Personal Information References 1. Looby S, Flanders A. Spine trauma. Radiol Clin North Am Jan;49(1): Fracture classifications in clinical practice. Seyed -Behrooz Mostofi Patel AA, Vaccaro AR. Thoracolumbar spine trauma classification. J Am Acad Orthop Surg Feb;18(2): Aebi M. Classification of thoracolumbar fractures and dislocations. Eur Spine J Mar;19 Suppl 1:S Kelly RP, Whitesides TE Jr. Treatment of lumbodorsal fracture-dislocations. Ann Surg May;167(5): McAfee PC, Yuan HA, Fredrickson BE, Lubicky JP The value of computed tomography in thoracolumbar fractures. An analysis of one hundred consecutive cases and a new classification. J Bone Joint Surg Am Apr;65(4): Denis F. Spinal instability as defined by the three-column spine concept in acute spinal trauma. Clin Orthop Relat Res Oct;(189): Ferguson RL, Allen BL Jr. An algorithm for the treatment of unstable thoracolumbar fractures. Orthop Clin North Am Jan;17(1): Sethi MK, Schoenfeld AJ, Bono CM, Harris MB. The evolution of thoracolumbar injury classification systems. Spine J Sep;9(9): Vaccaro AR, Zeiller SC, Hulbert RJ, Anderson PA, Harris M, Hedlund R, Harrop J, Dvorak M, Wood K, Fehlings MG, Fisher C, Lehman RA Jr, Anderson DG, Bono CM, Kuklo T, Oner FC. The thoracolumbar injury severity score: a proposed treatment algorithm. J Spinal Disord Tech Jun;18(3): Page 31 of 31