AO spine injury classification system: a revision proposal for the thoracic and lumbar spine

Abstract

Purpose The AO Spine Classification Group was established to propose a revised AO spine injury classification system. This paper provides details on the rationale, methodology, and results of the initial stage of the revision process for injuries of the thoracic and lumbar (TL) spine. Methods In a structured, iterative process involving five experienced spine trauma surgeons from various parts of the world, consecutive cases with TL injuries were classified independently by members of the classification group, and analyzed for classification reliability using the Kappa coefficient (j) and for accuracy using latent class analysis. The reasons for disagreements were examined systematically during review meetings. In four successive sessions, the system was revised until consensus and sufficient reproducibility were achieved. Results The TL spine injury system is based on three main injury categories adapted from the original Magerl AO concept: A (compression), B (tension band), and C (displacement) type injuries. Type-A injuries include four subtypes (wedge-impaction/split-pincer/incomplete burst/ complete burst); B-type injuries are divided between purely osseous and osseo-ligamentous disruptions; and C-type injuries are further categorized into three subtypes (hyperextension/translation/separation). There is no subgroup division. The reliability of injury types (A, B, C) was good (j = 0.77). The surgeons' pairwise Kappa ranged from 0.69 to 0.90. Kappa coefficients j for reliability of injury subtypes ranged from 0.26 to 0.78. Conclusions The proposed TL spine injury system is based on clinically relevant parameters. Final evaluation data showed reasonable reliability and accuracy. Further validation of the proposed revised AO Classification requires follow-up evaluation sessions and documentation by more surgeons from different countries and backgrounds and is subject to modification based on clinical parameters during subsequent phases.

The Michel Benoist and Robert Mulholland Yearly European Spine Journal Review: a survey of the “surgical and research” articles in the European Spine Journal, 2013

“…However, in that time there has been much change in imaging, so that it is appropriate that the classification should be revisited and updated. The paper by Reinhold et al [27] does this, making some suggested revisions to take account of changes in imagine, particularly our ability to image soft tissue injuries. It deserves careful reading, and the editorial by Aebi [28] further clarifies the issues.…”

Thoracolumbar Injury Severity Scoring Systems: A Review and Rationale for a New System Based on the AOSpine Thoracolumbar Injury Classification System

“…The revised AOSpine system uses the information provided by the three main injury categories from the original Magerl AO concept, namely: A) compression B) tension band and C) displacement type injuries [23]. Type A injuries were divided into subtypes (A0, A1, A2, A3, A4) and Type B were divided as well (B1, B2, B3), while all Type C injuries were not subdivided [23].…”

“…While the subtypes resemble the Magerl system, they lack the complexity that was previously the target of criticism and represent distinct morphologic injury patterns rather than a spectrum of less stable similar injuries. Along with the higher reproducibility and simplicity, the reliability and accuracy of injury evaluation under the new AOSpine classification parameters allow the system to take into account the variability and diversity of spinal cord injuries without loss of information content [23]. Thus, the recent AOSpine injury classification system provides a revised scheme that reduces the complexity of previous systems, while still maintaining clinically relevant classification reliability.…”

Efficacy of Ligamentotaxis of the Intact and Ruptured Posterior Longitudinal Ligament in Dorso-Lumbar Traumatic Spine Injuries

“…1,2 Thoraco-lumbar fractures are graded by AO classification with increasing severity as: Type A: vertebral compression fractures; Type B: anterior and posterior column injuries with distraction; Type C: anterior and posterior element injury with rotation. 3 Type A injuries are the result of compression by axial loading, for example compression and burst fractures. 4 Though, standard radiographs and CT scans can serve as imaging modalities, MRI scan is extremely useful to view ligaments (Fig 1) and to know status of spinal cord lesions and disco-ligamentous injuries.…”