Observation Of Reliability And Agreement Of Modified AO Spine Thoracolumbar Spine Injury

Background context Thoracolumbar fracture is the most common type of spinal fractures.On base of the principle simple,practical,comprehensive,repeatable,evaluating the damage degree and guiding treatment and predicting prognosis,there hasn’t been a classification method which is widely accepted and adopted yet.At present,the common classification systems are Denis classification,AO classification(Magerl system),SLC system and TLICS system.Because of the limitations of biomechanics and imaging technique,each classification has its own advantages and disadvantages which promotes higher requirements for classification.With the progress of medical technology and the development of imaginology,it is generally accepted that the classification system must incorporate the mechanism of fracture,fracture morphology,spine stability and neurological status.In 1983,based on biomechanical studies,Denis divided the vertebral column into three vertical parallel columns----anterior,middle and posterior.According to Denis’ s three-column theory,fractures involving middle column is unstable.However,Denis classification only analyze 412 cases of thoracolumbar fracture patients,of which only 53 cases were scanned by CT.Besides,the classification didn’t involve the intervertebral disc injury.In 1994,reviewing the X-ray and CT of 1445 cases of thoracolumbar spinal fracture buring 10 years,based on the fracture morphology and damage degree,Magerl proposed the AO classification with A to C type and further subdivided into 53 subtypes in the light of X-ray and CT respectively.Although the AO classification gives full consideration to a comprehensive description of fracture anatomy,fracture severity,stability and an inferred increased risk of neurological injury to some extent,it is overly complex.Besides,the Magerl system did not give formal consideration to the neurological injury or other clinical factors which may guide surgeon decision making,concepts increasingly embraced as classification systems are expected to provide prognostic,and treatment guidance.In contrast to Mgerl system,Mc Cormack proposed SLC scoring system(share loading scoring system)based on the studies of failure of posterior short-segment fixation,which provides a treatment option for spine surgeons.Nevertheless,the classification system still does not involve ligament injury and the mechanism of injury.For this reason,it cannot be used to recommend surgical indications.The TLICS(thoracolumbar injury classification and severity score)was proposed in 2005 by NASCIS on the base of the improvement of TLISS scoring system(Thoracolumbar injury severity score).The TLICS evaluates the neurological status,integrity of the PLC(posterior ligamentous complex),and injury morphology of each patient using descriptive categories.The reproducibility and feasibility of evaluating PLC integrity using magnetic resonance imaging(MRI)has been questioned.Also,the chosen severity scoring system guiding treatment may be a culture or region-specific decision and may not reflect global surgical preferences or the most rational approach to treatment.Therefore,in 2013,the AOSpine Trauma Knowledge Forum,an international group of academic spine surgeons,was tasked to develop and validate a classification system incorporating both fracture morphology and clinical factors relevant for surgical decision making,such as the presence of neurological deficits.The goal of this effort was to develop a widely accepted,comprehensive yet simple classification system which clinically acceptable intra-and interobserver reliability to be used for clinical practice.Objective To modify AO classification with clinically acceptable reliability and consistency.To investigate the advantages and disadvantages of AO classification.Methods 125 theoracolumbar cases with clinical and imaging data(X-ray,CT,3DCT,MRI)were chosen and provided to 2 orthopedics physicians(doctor 1 and 2).Denis classification,AO classification,SLC scoring system,TLICS scoring system and modified AO classification were adopted respectively to classify fracture and score.And then reclassified and rescored using the Kappa coefficient 1 month later.Results The Kappa statistic of doctor 1 and doctor 2 of Denis classification were 0.734 and 0.692.So the agreement of the same observer was k=0.713.The first and second interobserver kappa coefficient were 0.618 and 0.711.So the agreement of the two observer was kappa= 0.6645.The kappa statistic of doctor 1 and doctor 2 of AO classification were 0.734 and 0.692.So the agreement of the same observer was k=0.713.The first and second interobserver kappa coefficient were 0.618 and 0.711.So the agreement of the two observer was k= 0.6645.The k statistic of doctor 1 and doctor 2 of modified AO classification were 0.734 and 0.692.So the agreement of the same observer was k=0.713.The first and second interobserver k coefficient were 0.618 and 0.711.So the agreement of the two observer was kappa= 0.6645.The kappa statistic of doctor 1 and doctor 2 of SLC scoring system were 0.734 and 0.692.So the agreement of the same observer was kappa=0.713.The first and second interobserver k coefficient were 0.618 and 0.711.So the agreement of the two observer was kappa= 0.6645.The kappa statistic of doctor 1 and doctor 2 of TLICS scoring system were 0.734 and 0.692.So the agreement of the same observer was kappa=0.713.The first and second interobserver k coefficient were 0.618 and 0.711.So the agreement of the two observer was kappa= 0.6645.Of all the five classifications,modified AO classification had highest level of reliability and agreement with better clinical applicability.The TLICS has lower level and AO classification the lowest.Conclusions Modified AO classification has the advantages of both AO classification and TLICS.In addition to a description of morphology,the system also gives considerations to neurological status and the actual situation of patients,with higher reproducibility,which is critical to surgeon decision.But the system doesn’t involve the degree of injury of intervertebral disc and endplate and the influence on prognosis.