Several groups have compared the Thoracolumbar Injury Classification and Severity Score with the Denis  and AO  classification systems. Joaquim et al.  compared the Thoracolumbar Injury Classification and Severity Score with the AO classification in a multicenter retrospective study of 49 patients operatively treated for thoracolumbar spine trauma. The Thoracolumbar Injury Classification and Severity Score correlated well with AO fracture types, with higher scores consistent with AO Types B and C fractures. They concluded that the Thoracolumbar Injury Classification and Severity Score better reflected patient morbidity than the AO system through evaluation of neurologic status. Lewkonia et al.  evaluated 54 cases and distributed them to a diverse panel of reviewers tasked to calculate the Thoracolumbar Injury Classification and Severity scores and classify the fractures using the Denis classification  system. They used a new statistical method called the generalizability coefficient (ep2) to assess interobserver reliability. The generalizability coefficient is similar to the kappa value but incorporates additional variables to account for sources of error. A generalizability coefficient of 0 to 0.2 is poor agreement, 0.2 to 0.4 fair agreement, 0.4 to 0.6 moderate agreement, 0.6 to 0.8 good agreement, and 0.8 to 1 very good agreement. They found good interobserver agreement among panelists, surgeons, and trainees with respect to Thoracolumbar Injury Classification and Severity Score morphologic features (ep2 -0.74), posterior ligamentous complex (ep2 -0.72), and neurologic status (ep2 – 0.84). They found a similar interobserver agreement between the Denis classification and the Thoracolumbar Injury Classification and Severity Score (ep2 – 0.82), yet highlighted the purely descriptive nature and lack of prognostic or treatment recommendation of the Denis system.
The simplicity of the Thoracolumbar Injury Classification and Severity Score system serves as a strength and a potential weakness of its application. The system accurately directs management of thoracolumbar fractures associated with high energy, instability, or neurologic compromise, and low-energy single-column fractures. Despite this, the Thoracolumbar Injury Classification and Severity Score falls short in clearly defining management for patients with stable burst fractures who are neurologically intact, including patients with scores of 4. The patients in this intermediate group present with varied fracture patterns and neurologic status, and may be appropriately treated with operative or conservative interventions.
Some authors have proposed modifications in Thoracolumbar Injury Classification and Severity Score scoring system to improve management of indeterminately scored thoracolumbar fractures. Mattei et al.  suggested substratification of compression injuries to define whether one or two endplates (including the posterior vertebral cortex) were affected, with two endplate injuries being more likely to fail nonoperative management. Others believe routine MRI (to better define posterior ligamentous complex injuries) should be obtained in all patients with thoracolumbar burst fractures. Winklhofer et al.  reviewed Thoracolumbar Injury Classification and Severity scores for 100 patients before and after CT and MRI and found that 33 of them had additional occult posterior longitudinal ligament injuries. The total Thoracolumbar Injury Classification and Severity score changed from less than 5 to greater than 5 in 24 of 33 patients.
Multiple studies have shown a discrepancy between the proposed Thoracolumbar Injury Classification and Severity Score management and actual management of patients with neurologically intact burst fractures [5-7]. The largest retrospective review of patients with thoracolumbar spine trauma comparing proposed Thoracolumbar Injury Classification and Severity Score and actual management, found that 79 of 148 patients treated surgically (53%), had scores of 1 to 3, and an additional 5% had a score of 4. Joachim et al. [4-6] associated the lack of level I evidence and absence of clinical guidelines for the discordance between proposed management and delivered treatment.
The Thoracolumbar Injury Classification and Severity Score is an intuitive, clinically validated classification system designed to guide treatment of patients presenting with thoracolumbar spine trauma. Studies have shown high intra- and interobserver reliability, with a treatment algorithm for operative and nonoperative injuries validated through prospective clinical data. Despite its reliability and ease of use, the Thoracolumbar Injury Classification and Severity Score does not provide definitive insight into the treatment of neurologically intact burst fractures and indeterminate scores. Effort is continually being made to improve our understanding, description, and treatment of these injuries given the lack of universal adoption of any one thoracolumbar fracture classification system. In 2013 the AO spine group introduced a new classification scheme, the AO Spine Thoracolumbar Injury Classification System, which has been shown to have better reliability among surgeons in identifying morphologic features of fractures compared with the Thoracolumbar Injury Classification and Severity Score . Further prospective multicenter trials may identify additional patient and disease factors necessary to guide treatment of indeterminate scores furthering the clinical value of the Thoracolumbar Injury Classification and Severity Score.
We thank Arien L. Cherones (Department of Orthopaedics and Sports Medicine, University of Washington) for his assistance in preparing illustrations for this manuscript.
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