Classification of Thoracolumbar Spine Injuries

Transcription

1 Classification of Thoracolumbar Spine Injuries Guillem Saló Bru 1 IMAS. Hospitals del Mar i de l Esperança. ICATME. Institut Universitari Dexeus USP. UNIVERSITAT AUTÒNOMA DE BARCELONA

2 Objectives of classification Information about the severity of the given injury. Guide for further treatment: Which injuries are stable?? Which injuries benefit from spinal cord decompression?? Which injuries require surgical stabilization?? Prediction of clinical outcome.

3 Historical Classification Systems Author Year Summary Comments Watson-Jones 1938 First Classification Only for conservative treat Nicoll 1949 Differentiates stable from unstable fractures Foundation for subsequent classification systems Holdsworth 1963 Modifies previous classification systems to include the mechanisms of injury and two-column theory Fails to appreciate some burst fracture instabilities Kelly & Whitesides 1968 Refines the two-column model Classification guides treatment of neurologic deficit Louis & Goutallier 1977 Punctuate for each part of Vertebrae broken. Nonspecific for everyday use Denis 1983 Development of the three-column model The middle column is the primary determinant of mechanical stability.

4 Historical Classification Systems Author Year Summary Comments McAfee 1983 Based on CT appearance; classifies injuries into 6 categories Easily communicated type of injury with patients Ferguson and Allen 1984 Combines work done by Denis and McAfee; mechanistic classification to clarify patterns of thoracolumbar injury Cumbersome, nonspecific for everyday use McCormack (Load-Sharing) 1994 Developed in response to poor patient outcomes; grades injury based on amount of damage to vertebral body, the spread of fragments in fracture site and amount of corrected kyphosis Strong inter-observer reliability Gertzbein 1994 Suggests a posterior component, anterior component and body component Involves the vertebral body as it relates to kyphosis. Magerl/AO 1994 Classifies types of fractures into A, B, or C and into subcategories subsequently Moderate inter-observer reliability

5 Denis Classification 1983 Based on the review of 412 thoracolumbar injuries, CT scans of 53 patients and surgical notes from 120 cases. Primarily based on pathologic anatomy of different types of spinal injuries, each of which was based on a different mechanism of injury. Supported on a three-columns concept of spine. Denis F. Spine. 1983

6 Denis: Three-column model Anterior column- formed by the anterior longitudinal ligament, the anterior annulus, and the anterior portion of the vertebral body Middle column- the critical feature. Very important to spinal stability; consists of posterior longitudinal ligament, the posterior portion of the annulus, and the posterior aspect of the vertebral body Posterior column- includes the neural arch, facet joints and capsules, ligamentum flavum, and remaining ligamentous complex Denis F. Spine. 1983

7 Denis Classification. Studies have supported the three-column theory and found that the middle column is the primary determinant of mechanical stability of the thoracolumbar region of the spine. Panjabi, MM. Spine, 1995.

8 Denis: Three-column model Basic modes of failure of the columns in the four major types of spinal Injuries. % ANTERIOR MIDDLE POSTERIOR I. COMPRESSION 47 COMPRESSION NONE NONE/ DISTRACTION II. BURST 15 COMPRESIÓN COMPRESSION NONE III. SEAT-BELT 5 NONE / COMPRESSION DISTRACTION DISTRACTION IV. FRACTURE- DISLOCATION 16 COMPRESSIÓN ROTATION/ SHEAR DISTRACTION/ ROTATION/ SHEAR DISTRACTION ROTATION/ SHEAR V. MINOR INJURIES: 17% (transverse, articular, spinous process, pars interarticularis, ) Denis F. Spine. 1983

9 Denis: Compression fractures (47%) I-A Anterior: A: Failure of both end plates and vertebral body (16 %). B: Failure of the upper endplate (62%). C: Failure of the inferior endplate (6%). D: Failure of the central vertebral body without end-plate fracture (15%). I-B Lateral: A B C D

10 Denis: Burst fractures (15%) II-A. Failure of both end plates (24% axial compression). II-B. Failure of the upper endplate (49% axial compression & flexion). II-C. Failure of the upper endplate (7% axial compression & flexion).. II-D. Burst-rotation (15% axial compression & rotation). II-E. Burst-lateral flexion (5% axial compression & lateral flexion).

11 Denis: Burst fractures Burst Fracture Type IIA Burst Fracture Type IIC

12 Denis: Seat-Belt fractures (5%) One-level injuries: III-A. Bony injury (Chance fracture) (47%). III-B. Ligamentous injury (10%). Bone Ligaments Two-level injuries: III-C. Through bone middle column (26%). III-D. Through ligamentous middle column (16%).

13 Denis: Seat-Belt fractures (5%) Seat-belt fracture III-A. Seat-belt fracture III-B. Seat-belt fracture III-C. Seat-belt fracture III-D.

14 Denis: Fracture Dislocations (16%) IV-A. Flexion-rotation (13%). IV-B. Shear type (1%). IV-C. Flexion distraction (1%).

15 Denis: Fracture Dislocations (16%) Fracture Dislocation IV-A. Fracture Dislocation IV-B. Fracture Dislocation IV-C.

16 Load Sharing Classification Created system in response to poor patient outcomes when the vertebral body sustained a disproportionately severe injury. Load-Sharing Classification: a straight-forward way to describe the amount of bony comminution in a spinal fracture. McCormack et al. Spine, 1994

17 Load Sharing Classification Classification system grades: Amount of damaged vertebral body. Spread of the fragments in the fracture sight. Amount of corrected kyphosis. Three degrees of severity for each item. Failure of posterior short-segment fixation correlates with a total injury severity point value 7. McCormack et al. Spine, 1994

18 Load Sharing Classification System can be used pre-operatively to: 1. Predict screw breakage when short segment, posteriorly placed pedicle screw implants are being used 2. Describe any spinal injury for retrospective studies 3. Select spinal fractures for anterior reconstruction with strut graft McCormack et al. Spine, 1994

19 Load Sharing Classification Reliability Dai and Jin (2005): Inter-observer and intra-observer reliability of the Load Sharing system was evaluated by 5 observes on 2 occasions. Analysis found high levels of agreement when Load Sharing Classification was used to assess thoracolumbar burst fractures. Concluded that the system could be applied with excellent reliability. But this system classification fails to consider: Ligamentous injury. Injury of the neural elements. Dai LY, Jin WJ. Spine, 2005.

20 AO Classification Revision of 1445 consecutive thoracolumbar injuries Primarily based on pathomorphological criteria. Supported on a two-columns concept of spine. Categories based on: Main mechanism of injury Pathomorphological uniformity Prognostic aspects regarding healing potential Magerl et al. Eur Spine J

21 AO Classification Classification reflects progressive scale of morphological damage by which the degree of instability is determined Consists of a grid for sub-grouping injuries into three types: A, B and C Every type has three groups, each of which contains three subgroups with specifications. Magerl et al. Eur Spine J

22 AO Classification Types have a fundamental injury pattern which is determined by the three most important mechanisms acting on the spine 1. Compression 2. Distraction 3. Axial torque Magerl et al. Eur Spine J

23 AO Classification - A, B, C s Type A: Vertebral body compression- injury patterns of the vertebral body Posterior elements remain intact. Type B: Anterior and posterior element injuries with distraction, characterized by transverse disruption either anteriorly or posteriorly B.1 & B.2 hyperflexion mechanism. B.3 Hiperextension. Type C: Anterior and posterior injuries with rotation or translation injury patters resulting from axial torque. C1: A+rotation. C2: B+ rotation. C3: translation. Magerl et al. Eur Spine J

24 AO Classification Groups and subgroups. Magerl et al. Eur Spine J

25 AO Classification A3.3 B1.2 B2.2 C3.2

26 Reproducibility studies Onner et al: Studied the interobserver and intra-observer reproducibility of the Magerl (AO) in comparison with the Denis classification. The agreement was better with the Denis classification, but the variance was higher due to the difficulty of finding proper categories for some injury patterns. Although the AO classification allows proper registration of all kinds of injury, the reproducibility, especially at the type level, is fair with CT scans and moderate with MRI. In spite of this, the authors recommend the use of the Magerl (AO) classification because it allows categorization of injuries to all relevant parts of the spine.

27 Reproducibility studies Blauth el al: interobserver reliability of AO classification system. 22 hospitals evaluated 14 radiographs and CT scans. The mean interobserver agreement for all fourteen cases was found to be 67% (41±91 %),when only the three main types (A, B, C) were used. The reliability decreased by increasing the categories. Orthopade, 1999; NASS, 2004

28 Reproducibility studies Wood, et al: 31 CT scans and radiographs of acute traumatic fractures of the thoracolumbar spine evaluated by 19 observers. Classified according to both AO and Denis classification system. Only moderate reproducibility and repeatability among well-trained spine surgeons using AO and Denis classification systems Wood JBJS 2005

29 Reproducibility studies To assess the inter-observer reliability and intra-observer reproducibility of standard radiographic evaluation of 150 thoraco-lumbar fractures using the AO-classification (A,B,C). 6 observers, 2 sessions. The infuence of clinical information on agreement levels was also evaluated. The overall inter-observer agreement was rated as fair (0.291) in the first session and moderate (0.403) in the second. The increased level of agreement in the second session was attributed to the value of additional clinical information Eur Spine J, 2006

30 Thoracolumbar Injury Classification and Severity Score - TLICS (2005). Three variables were identified by authors as critical to clinical decision-making in thoracolumbar trauma: 1. The morphology of injury as determined by reviewing the pattern of disruption on available imaging studies. 2. The integrity of the posterior ligamentous complex (PLC). 3. The neurologic status of the patient. Vaccaro et al. Spine 2005.

31 Thoracolumbar Injury Classification and Severity Score - TLICS (2005). Morphology: Fracture pattern Vaccaro et al. Spine 2005.

32 Thoracolumbar Injury Classification and Severity Score - TLICS (2005). Integrity of the posterior ligamentous complex (supraspinous ligament, interspinous ligament, ligamentum flavum, and the facet joint capsules). Neurologic status. Score 3 : nonoperative injury. Score = 4 might be handled conservatively or surgically. Score 5: surgical intervention may be considered. Vaccaro et al. Spine 2005.

33 Thoracolumbar Injury Classification and Severity Score - TLICS (2005). Surgical Approach: Integrity of the PCL. Neurologic status of the patient. Vaccaro et al. Spine 2005.

34 Reproducibility studies The TLICS has good reliability and compares favorably to other contemporary thoracolumbar fracture classification systems. Studies from the same group of authors Short-term experience.

35 What classification is more used today? Review of the literature. Indexed articles about thoracolumbar fractures published in the last 10 years ( ): 195. Using a classification system: Last 5 years 5 to 10 years Denis 1983 Gertzbein 1994 Load Sharing 1994 Magerl/AO 1994 TLICS 2005

36 Summary Currently no classification system that has achieved global clinical utility and universal acceptance. The attempts to develop all-inclusive schemes are highly divided and not truly useful for physician communication, nor are they reproducible in their ability to repeatedly classify injuries. Few studies have evaluated the effectiveness of the different systems. More recent classification system needs a longterm follow-up to know its clinical utility.