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Timothy E Hewett - One of the best experts on this subject based on the ideXlab platform.
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strain response of the anterior cruciate ligament to uniplanar and multiplanar loads during simulated landings implications for Injury Mechanism
American Journal of Sports Medicine, 2016Co-Authors: Ata M Kiapour, Constantine K Demetropoulos, Carmen E Quatman, Samuel C Wordeman, Vijay K Goel, Timothy E HewettAbstract:Background:Despite basic characterization of the loading factors that strain the anterior cruciate ligament (ACL), the interrelationship(s) and additive nature of these loads that occur during noncontact ACL injuries remain incompletely characterized.Hypothesis:In the presence of an impulsive axial compression, simulating vertical ground-reaction force during landing (1) both knee abduction and internal tibial rotation moments would result in increased peak ACL strain, and (2) a combined multiplanar loading condition, including both knee abduction and internal tibial rotation moments, would increase the peak ACL strain to levels greater than those under uniplanar loading modes alone.Study Design:Controlled laboratory study.Methods:A cadaveric model of landing was used to simulate dynamic landings during a jump in 17 cadaveric lower extremities (age, 45 ± 7 years; 9 female and 8 male). Peak ACL strain was measured in situ and characterized under impulsive axial compression and simulated muscle forces (base...
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timing sequence of multi planar knee kinematics revealed by physiologic cadaveric simulation of landing implications for acl Injury Mechanism
Clinical Biomechanics, 2014Co-Authors: Timothy E Hewett, Ata M Kiapour, Carmen E Quatman, Vijay K Goel, S C Wordeman, Constantine K DemetropoulosAbstract:article i nfo Background: Challenges in accurate, in vivo quantification of multi-planar knee kinematics and relevant timing sequence during high-risk injurious tasks pose challenges in understanding the relative contributions of joint loads in non-contact Injury Mechanisms. Biomechanical testing on human cadaveric tissue, if properly designed, offers a practical means to evaluate joint biomechanics and Injury Mechanisms. This study seeks to investigate the detailed interactions between tibiofemoral joint multi-planar kinematics and anterior cruciate ligament strain in a cadaveric model of landing using a validated physiologic drop-stand apparatus. Methods: Sixteen instrumented cadaveric legs, mean 45(SD 7) years (8 female and 8 male) were tested. Event timing sequence, change in tibiofemoral kinematics (position, angular velocity and linear acceleration) and change in anterior cruciate ligament strain were quantified. Findings: The proposed cadaveric model demonstrated similar tibiofemoral kinematics/kinetics as reported measurements obtained from in vivo studies. While knee flexion, anterior tibial translation, knee abduction and increased anterior cruciate ligament strain initiated and reached maximum values almost simultaneously, internal tibial rotation initiated and peaked significantly later (P b 0.015 for all comparisons). Further, internal tibial rotation reached mean 1.8(SD 2.5)°, almost 63% of its maximum value, at the time that peak anterior cru- ciate ligament strain occurred, while both anterior tibial translation and knee abduction had already reached their peaks. Interpretation: Together, these findings indicate that although internal tibial rotation contributes to increased anterior cruciate ligament strain, it is secondary to knee abduction and anterior tibial translation in its effect on anterior cruciate ligament strain and potential risk of Injury.
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video analysis of trunk and knee motion during non contact anterior cruciate ligament Injury in female athletes lateral trunk and knee abduction motion are combined components of the Injury Mechanism
British Journal of Sports Medicine, 2009Co-Authors: Timothy E Hewett, Joseph S Torg, Barry P BodenAbstract:Background: The combined positioning of the trunk and knee in the coronal and sagittal planes during non-contact anterior cruciate ligament (ACL) Injury has not been previously reported. Hypothesis: During ACL Injury female athletes demonstrate greater lateral trunk and knee abduction angles than ACL-injured male athletes and uninjured female athletes. Design: Cross-section control-cohort design. Methods: Analyses of still captures from 23 coronal (10 female and 7 male ACL-injured players and 6 female controls) or 28 sagittal plane videos performing similar landing and cutting tasks. Significance was set at p⩽0.05. Results: Lateral trunk and knee abduction angles were higher in female compared to male athletes during ACL Injury (p⩽0.05) and trended toward being greater than female controls (p = 0.16, 0.13, respectively). Female ACL-injured athletes showed less forward trunk lean than female controls (mean (SD) initial contact (IC): 1.6 (9.3)° vs 14.0 (7.3)°, p⩽0.01). Conclusion: Female athletes landed with greater lateral trunk motion and knee abduction during ACL Injury than did male athletes or control females during similar landing and cutting tasks. Clinical relevance: Lateral trunk and knee abduction motion are important components of the ACL Injury Mechanism in female athletes as observed from video evidence of ACL Injury.
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anterior cruciate ligament injuries in female athletes part 1 Mechanisms and risk factors
American Journal of Sports Medicine, 2006Co-Authors: Timothy E Hewett, Gregory D Myer, Kevin R FordAbstract:The Mechanism underlying gender disparity in anterior cruciate ligament Injury risk is likely multifactorial in nature. Several theories have been proposed to explain the Mechanisms underlying the gender difference in anterior cruciate ligament Injury rates. These theories include the intrinsic variables of anatomical, hormonal, neuromuscular, and biomechanical differences between genders and extrinsic variables. Identification of both extrinsic and intrinsic risk factors associated with the anterior cruciate ligament Injury Mechanism may provide direction for targeted prophylactic treatment to high-risk individuals.
Alexander R. Vaccaro - One of the best experts on this subject based on the ideXlab platform.
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the development and evaluation of the subaxial Injury classification scoring system for cervical spine trauma
Clinical Orthopaedics and Related Research, 2011Co-Authors: Peter G Whang, Alpesh A Patel, Alexander R. VaccaroAbstract:Background Fractures and dislocations of the subaxial cervical spine may give rise to devastating consequences. Previous algorithms for describing cervical trauma largely depend on retrospective reconstructions of Injury Mechanism and utilize nonspecific terminology which thus diminish their clinical relevance add to the difficulty of educating doctors and performing prospective research.
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the influence of fracture Mechanism and morphology on the reliability and validity of two novel thoracolumbar Injury classification systems
Spine, 2007Co-Authors: Peter G Whang, Alexander R. Vaccaro, Alpesh A Patel, James S Harrop, Kornelius A Poelstra, Greg D Anderson, Todd J Albert, Alan S Hilibrand, Ashwini Sharan, John K RatliffAbstract:STUDY DESIGN The Thoracolumbar Injury Severity Score (TLISS) and the Thoracolumbar Injury Classification and Severity Score (TLICS) were prospectively evaluated. OBJECTIVES To compare the reliability and validity of the TLISS and TLICS schemes to determine the importance of Injury Mechanism and morphology to the identification and treatment of thoracolumbar fractures. SUMMARY OF BACKGROUND DATA Two novel algorithms have been developed for the categorization and management of thoracolumbar injuries: the TLISS system emphasizing Injury Mechanism and the TLICS scheme involving Injury morphology. METHODS The clinical and radiographic findings of 25 patients with thoracolumbar fractures were prospectively presented to 5 groups of surgeons with disparate levels of training and experience with spinal trauma. These injuries were consecutively scored, first using the TLISS and then 3 months later with the TLICS. The recommended treatments proposed by the 2 schemes were compared with the actual management of each patient. RESULTS For both algorithms, the interrater kappa statistics of all subgroups (Mechanism/morphology, status of the posterior ligaments, total score, predicted management) were within the range of moderate to substantial reproducibility (0.45-0.74), and there were no statistically significant differences noted between the respective kappa values. Interrater correlation was higher for the TLISS paradigm on Mechanism/morphology, integrity of the posterior ligaments, and proposed management (P < or = 0.01). The TLISS and TLICS schemes both exhibited excellent overall validity. CONCLUSIONS Although both schemes were noted to have substantial reproducibility and validity, our results indicate the TLISS is more reliable than the TLICS, suggesting that the Mechanism of trauma may be a more valuable parameter than fracture morphology for the classification and treatment thoracolumbar injuries. Since these Injury characteristics are interrelated and are critical to the maintenance of spinal stability, we think that both concepts should be considered during the assessment and management of these patients.
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reliability of a novel classification system for thoracolumbar injuries the thoracolumbar Injury severity score
Spine, 2006Co-Authors: Alexander R. Vaccaro, Eli M Baron, James A Sanfilippo, Sidney M Jacoby, Jacob Steuve, Eric L Grossman, Matthew J Dipaola, Paul Ranier, Luke S Austin, Ray RopiakAbstract:STUDY DESIGN Prospective study of 5 spine surgeons rating 71 clinical cases of thoracolumbar spinal injuries using the Thoracolumbar Injury Severity Score (TLISS) and then re-rating the cases in a different order 1 month later. OBJECTIVE To determine the reliability of the TLISS system. SUMMARY OF BACKGROUND DATA The TLISS is a recently introduced classification system for thoracolumbar spinal column injures designed to simplify Injury classification and facilitate treatment decision making. Before being widely adopted, the reliability of the TLISS must be studied. METHODS A total of 71 cases of thoracolumbar spinal trauma were distributed on CD-ROM to 5 attending spine surgeons, including clinical/radiographic data, details of the TLISS, and a scoring sheet in which cases would be scored using the system. The surgeons were later assigned the task with the cases reordered. Intraobserver and interobserver reliability was calculated for TLISS components, total score, and surgeon's treatment decision using the Cohen unweighted kappa coefficients and Spearman rank-order correlation. RESULTS Interrater reliability assessed by generalized kappa coefficients was 0.33 +/- 0.03 for Injury Mechanism, 0.91 +/- 0.02 for neurologic status, 0.35 +/- 0.03 for posterior ligamentous complex status, 0.29 +/- 0.02 for TLISS total, and 0.52 +/- 0.03 for treatment recommendation. Respective results using the Spearman correlation were 0.35 +/- 0.04, 0.94 +/- 0.01, 0.48 +/- 0.04, 0.65 +/- 0.03, and 0.51 +/- 0.04. Surgeons agreed with the TLISS recommendation 96.4% of the time. Intrarater kappa coefficients were 0.57 +/- 0.04 for Injury Mechanism, 0.93 +/- 0.02 for neurologic status, 0.48 +/- 0.04 for posterior ligamentous complex status, 0.46 +/- 0.03 for TLISS total, and 0.62 +/- 0.04 for treatment recommendation. Respective results using the Spearman correlation were 0.70 +/- 0.04, 0.95 +/- 0.02, 0.59 +/- 0.05, 0.77 +/- 0.04, and 0.59 +/- 0.05. CONCLUSIONS The TLISS has good reliability and compares favorably to other contemporary thoracolumbar fracture classification systems.
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intrarater and interrater reliability and validity in the assessment of the Mechanism of Injury and integrity of the posterior ligamentous complex a novel Injury severity scoring system for thoracolumbar injuries invited submission from the joint section meeting on disorders of the spine and peripheral nerves march 2005
Journal of Neurosurgery, 2006Co-Authors: James S Harrop, Alexander R. Vaccaro, Eli M Baron, Marcel F Dvorak, John R Hurlbert, Jared T Wilsey, Christopher I Shaffrey, Charles G Fisher, F C Oner, Kirkham B WoodAbstract:OBJECT: A new classification and treatment algorithm for thoracolumbar injuries was recently introduced by Vaccaro and colleagues in 2005. A thoracolumbar Injury severity scale (TLISS) was proposed for grading and guiding treatment for these injuries. The scale is based on the following: 1) the Mechanism of Injury; 2) the integrity of the posterior ligamentous complex (PLC); and 3) the patient's neurological status. The reliability and validity of assessing Injury Mechanism and the integrity of the PLC was assessed. METHODS: Forty-eight spine surgeons, consisting of neurosurgeons and orthopedic surgeons, reviewed 56 clinical thoracolumbar Injury case histories. Each was classified and scored to determine treatment recommendations according to a novel classification system. After 3 months the case histories were reordered and the physicians repeated the exercise. Validity of this classification was good among reviewers; the vast majority (> 90%) agreed with the system's treatment recommendations. Surgeons were unclear as to a cogent description of PLC disruption and fracture Mechanism. CONCLUSIONS: The TLISS demonstrated acceptable reliability in terms of intra- and interobserver agreement on the algorithm's treatment recommendations. Replacing Injury Mechanism with a description of Injury morphology and better definition of PLC Injury will improve inter- and intraobserver reliability of this Injury classification system.
Ata M Kiapour - One of the best experts on this subject based on the ideXlab platform.
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strain response of the anterior cruciate ligament to uniplanar and multiplanar loads during simulated landings implications for Injury Mechanism
American Journal of Sports Medicine, 2016Co-Authors: Ata M Kiapour, Constantine K Demetropoulos, Carmen E Quatman, Samuel C Wordeman, Vijay K Goel, Timothy E HewettAbstract:Background:Despite basic characterization of the loading factors that strain the anterior cruciate ligament (ACL), the interrelationship(s) and additive nature of these loads that occur during noncontact ACL injuries remain incompletely characterized.Hypothesis:In the presence of an impulsive axial compression, simulating vertical ground-reaction force during landing (1) both knee abduction and internal tibial rotation moments would result in increased peak ACL strain, and (2) a combined multiplanar loading condition, including both knee abduction and internal tibial rotation moments, would increase the peak ACL strain to levels greater than those under uniplanar loading modes alone.Study Design:Controlled laboratory study.Methods:A cadaveric model of landing was used to simulate dynamic landings during a jump in 17 cadaveric lower extremities (age, 45 ± 7 years; 9 female and 8 male). Peak ACL strain was measured in situ and characterized under impulsive axial compression and simulated muscle forces (base...
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timing sequence of multi planar knee kinematics revealed by physiologic cadaveric simulation of landing implications for acl Injury Mechanism
Clinical Biomechanics, 2014Co-Authors: Timothy E Hewett, Ata M Kiapour, Carmen E Quatman, Vijay K Goel, S C Wordeman, Constantine K DemetropoulosAbstract:article i nfo Background: Challenges in accurate, in vivo quantification of multi-planar knee kinematics and relevant timing sequence during high-risk injurious tasks pose challenges in understanding the relative contributions of joint loads in non-contact Injury Mechanisms. Biomechanical testing on human cadaveric tissue, if properly designed, offers a practical means to evaluate joint biomechanics and Injury Mechanisms. This study seeks to investigate the detailed interactions between tibiofemoral joint multi-planar kinematics and anterior cruciate ligament strain in a cadaveric model of landing using a validated physiologic drop-stand apparatus. Methods: Sixteen instrumented cadaveric legs, mean 45(SD 7) years (8 female and 8 male) were tested. Event timing sequence, change in tibiofemoral kinematics (position, angular velocity and linear acceleration) and change in anterior cruciate ligament strain were quantified. Findings: The proposed cadaveric model demonstrated similar tibiofemoral kinematics/kinetics as reported measurements obtained from in vivo studies. While knee flexion, anterior tibial translation, knee abduction and increased anterior cruciate ligament strain initiated and reached maximum values almost simultaneously, internal tibial rotation initiated and peaked significantly later (P b 0.015 for all comparisons). Further, internal tibial rotation reached mean 1.8(SD 2.5)°, almost 63% of its maximum value, at the time that peak anterior cru- ciate ligament strain occurred, while both anterior tibial translation and knee abduction had already reached their peaks. Interpretation: Together, these findings indicate that although internal tibial rotation contributes to increased anterior cruciate ligament strain, it is secondary to knee abduction and anterior tibial translation in its effect on anterior cruciate ligament strain and potential risk of Injury.
Thomas R Oxland - One of the best experts on this subject based on the ideXlab platform.
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differential histopathological and behavioral outcomes eight weeks after rat spinal cord Injury by contusion dislocation and distraction Mechanisms
Journal of Neurotrauma, 2016Co-Authors: Kinon Chen, Jie Liu, Peggy Assinck, Tim Bhatnagar, Femke Streijger, Qingan Zhu, Marcel F Dvorak, Brian K Kwon, Wolfram Tetzlaff, Thomas R OxlandAbstract:The objective of this study was to compare the long-term histological and behavioral outcomes after spinal cord Injury (SCI) induced by one of three distinct biomechanical Mechanisms: dislocation, contusion, and distraction. Thirty male Sprague-Dawley rats were randomized to incur a traumatic cervical SCI by one of these three clinically relevant Mechanisms. The injured cervical spines were surgically stabilized, and motor function was assessed for the following 8 weeks. The spinal cords were then harvested for histologic analysis. Quantification of white matter sparing using Luxol fast blue staining revealed that dislocation Injury caused the greatest overall loss of white matter, both laterally and along the rostrocaudal axis of the injured cord. Distraction caused enlarged extracellular spaces and structural alteration in the white matter but spared the most myelinated axons overall. Contusion caused the most severe loss of myelinated axons in the dorsal white matter. Immunohistochemistry for the neuronal marker NeuN combined with Fluoro Nissl revealed that the dislocation Mechanism resulted in the greatest neuronal cell losses in both the ventral and dorsal horns. After the distraction Injury Mechanism, animals displayed no recovery of grip strength over time, in contrast to the animals subjected to contusion or dislocation injuries. After the dislocation Injury Mechanism, animals displayed no improvement in the grooming test, in contrast to the animals subjected to contusion or distraction injuries. These data indicate that different SCI Mechanisms result in distinct patterns of histopathology and behavioral recovery. Understanding this heterogeneity may be important for the future development of therapeutic interventions that target specific neuropathology after SCI.
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secondary pathology following contusion dislocation and distraction spinal cord injuries
Experimental Neurology, 2008Co-Authors: Anthony M Choo, Jie Liu, Marcel F Dvorak, Wolfram Tetzlaff, Thomas R OxlandAbstract:Preclinical studies for spinal cord Injury (SCI) have utilized transection and contusion Injury paradigms even though human SCIs occur by a spectrum of primary Injury Mechanisms such as spinal cord contusion from vertebral burst fracture, shearing from fracture-dislocation, and stretching from distraction injuries. We contrasted the neuropathology in animal models mimicking these clinically relevant injuries at an early 3-hour time-point in order to relate patterns of secondary pathology to the primary Injury Mechanism. Axolemma compromise, detected by the intracellular penetration of dextran-conjugated fluorophores, was localized to the contusion epicentre but extended rostrally following dislocation and distraction injuries. Dextran infused post-trauma revealed extensive axolemma resealing whereas only modest membrane recovery was detected in neuronal somata. Fracture-dislocations produced greater axonal degeneration than either contusion or distraction injuries as evidenced by reduced neurofilament immunostaining in ventral tracts, increased β-amyloid precursor protein accumulation in lateral funiculi, and a longer lesion in the dorsal corticospinal tract. In the gray matter, cytochrome c release from neuronal mitochondria, indicative of early apoptosis, was detected within the penumbrae of the contusion and dislocation injuries only. Neurons positive for the oxidative stress marker 3-nitrotyrosine were most numerous rostral to the dislocation epicentre. Microglial activation was localized to the contusion epicentre, extended rostro-caudally following dislocation, but was similar to surgical controls after distraction injuries. Reactive astrocytes extended rostro-caudally only following dislocation injuries. Hence, the primary Injury Mechanism alters the pattern of secondary degeneration indicating that different neuroprotective strategies may ultimately be required for treating distinct clinically relevant SCIs.
Marcel F Dvorak - One of the best experts on this subject based on the ideXlab platform.
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differential histopathological and behavioral outcomes eight weeks after rat spinal cord Injury by contusion dislocation and distraction Mechanisms
Journal of Neurotrauma, 2016Co-Authors: Kinon Chen, Jie Liu, Peggy Assinck, Tim Bhatnagar, Femke Streijger, Qingan Zhu, Marcel F Dvorak, Brian K Kwon, Wolfram Tetzlaff, Thomas R OxlandAbstract:The objective of this study was to compare the long-term histological and behavioral outcomes after spinal cord Injury (SCI) induced by one of three distinct biomechanical Mechanisms: dislocation, contusion, and distraction. Thirty male Sprague-Dawley rats were randomized to incur a traumatic cervical SCI by one of these three clinically relevant Mechanisms. The injured cervical spines were surgically stabilized, and motor function was assessed for the following 8 weeks. The spinal cords were then harvested for histologic analysis. Quantification of white matter sparing using Luxol fast blue staining revealed that dislocation Injury caused the greatest overall loss of white matter, both laterally and along the rostrocaudal axis of the injured cord. Distraction caused enlarged extracellular spaces and structural alteration in the white matter but spared the most myelinated axons overall. Contusion caused the most severe loss of myelinated axons in the dorsal white matter. Immunohistochemistry for the neuronal marker NeuN combined with Fluoro Nissl revealed that the dislocation Mechanism resulted in the greatest neuronal cell losses in both the ventral and dorsal horns. After the distraction Injury Mechanism, animals displayed no recovery of grip strength over time, in contrast to the animals subjected to contusion or dislocation injuries. After the dislocation Injury Mechanism, animals displayed no improvement in the grooming test, in contrast to the animals subjected to contusion or distraction injuries. These data indicate that different SCI Mechanisms result in distinct patterns of histopathology and behavioral recovery. Understanding this heterogeneity may be important for the future development of therapeutic interventions that target specific neuropathology after SCI.
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secondary pathology following contusion dislocation and distraction spinal cord injuries
Experimental Neurology, 2008Co-Authors: Anthony M Choo, Jie Liu, Marcel F Dvorak, Wolfram Tetzlaff, Thomas R OxlandAbstract:Preclinical studies for spinal cord Injury (SCI) have utilized transection and contusion Injury paradigms even though human SCIs occur by a spectrum of primary Injury Mechanisms such as spinal cord contusion from vertebral burst fracture, shearing from fracture-dislocation, and stretching from distraction injuries. We contrasted the neuropathology in animal models mimicking these clinically relevant injuries at an early 3-hour time-point in order to relate patterns of secondary pathology to the primary Injury Mechanism. Axolemma compromise, detected by the intracellular penetration of dextran-conjugated fluorophores, was localized to the contusion epicentre but extended rostrally following dislocation and distraction injuries. Dextran infused post-trauma revealed extensive axolemma resealing whereas only modest membrane recovery was detected in neuronal somata. Fracture-dislocations produced greater axonal degeneration than either contusion or distraction injuries as evidenced by reduced neurofilament immunostaining in ventral tracts, increased β-amyloid precursor protein accumulation in lateral funiculi, and a longer lesion in the dorsal corticospinal tract. In the gray matter, cytochrome c release from neuronal mitochondria, indicative of early apoptosis, was detected within the penumbrae of the contusion and dislocation injuries only. Neurons positive for the oxidative stress marker 3-nitrotyrosine were most numerous rostral to the dislocation epicentre. Microglial activation was localized to the contusion epicentre, extended rostro-caudally following dislocation, but was similar to surgical controls after distraction injuries. Reactive astrocytes extended rostro-caudally only following dislocation injuries. Hence, the primary Injury Mechanism alters the pattern of secondary degeneration indicating that different neuroprotective strategies may ultimately be required for treating distinct clinically relevant SCIs.
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intrarater and interrater reliability and validity in the assessment of the Mechanism of Injury and integrity of the posterior ligamentous complex a novel Injury severity scoring system for thoracolumbar injuries invited submission from the joint section meeting on disorders of the spine and peripheral nerves march 2005
Journal of Neurosurgery, 2006Co-Authors: James S Harrop, Alexander R. Vaccaro, Eli M Baron, Marcel F Dvorak, John R Hurlbert, Jared T Wilsey, Christopher I Shaffrey, Charles G Fisher, F C Oner, Kirkham B WoodAbstract:OBJECT: A new classification and treatment algorithm for thoracolumbar injuries was recently introduced by Vaccaro and colleagues in 2005. A thoracolumbar Injury severity scale (TLISS) was proposed for grading and guiding treatment for these injuries. The scale is based on the following: 1) the Mechanism of Injury; 2) the integrity of the posterior ligamentous complex (PLC); and 3) the patient's neurological status. The reliability and validity of assessing Injury Mechanism and the integrity of the PLC was assessed. METHODS: Forty-eight spine surgeons, consisting of neurosurgeons and orthopedic surgeons, reviewed 56 clinical thoracolumbar Injury case histories. Each was classified and scored to determine treatment recommendations according to a novel classification system. After 3 months the case histories were reordered and the physicians repeated the exercise. Validity of this classification was good among reviewers; the vast majority (> 90%) agreed with the system's treatment recommendations. Surgeons were unclear as to a cogent description of PLC disruption and fracture Mechanism. CONCLUSIONS: The TLISS demonstrated acceptable reliability in terms of intra- and interobserver agreement on the algorithm's treatment recommendations. Replacing Injury Mechanism with a description of Injury morphology and better definition of PLC Injury will improve inter- and intraobserver reliability of this Injury classification system.