The Development Of Prognosis Score Of Surgical Outcome Of Thoracic Ossification Of The Ligamentum Flavum

Background and Objective:Thoracic myelopathy caused by thoracic ossification of the ligamentum flavum(TOLF)is a rare and unexplained ligament ossification disease,which is the main cause of thoracic spinal stenosis.Progression of TOLF is slow and difficult to visualize.Conservative treatment is usually ineffective,and it has to be surgically treated when symptoms appear.Several surgical procedures have been developed for the treatment of TOLF.the most common and classic one is the posterior decompression by laminectomy.Due to the low incidence of TOLF and the difficulty of surgery,it is difficult to collect the case data of a single center with a large sample.At present,a large number of literatures have studied the factors influencing the postoperative recovery of TOLF,but surgical outcomes vary.What is more,there is no clear scoring system that can predict the surgical outcome of TOLF in a repeatable and quantifiable manner.Insufficient judgment regarding surgical prognosis may give rise to inappropriate surgical strategy and cause great inconvenience to patients.Therefore,it is necessary to establish a standardized quantitative scoring system for TOLF.In this paper,clinical data of patients undergoing surgical treatment for TOLF were retrospectively collected and analyzed from April 2012 to August 2017 at a single institution in China.Our aim is to establish a standardized scoring system for TOLF and validate whether the TOLF score is a predictor for surgical prognosis.Methods:1.A retrospective review was conducted for all patients with thoracic OYL causing myelopathy received surgical decompression from April 2012 to February 2019 at a single institution in China.The modified Japanese Orthopedic Association scores system(mJOA)was used to evaluate preoperative and postoperative neurologic status According to the postoperative recovery ratio(RR).all patients were divided into an excellent group(75%?RR?100%).a good group(50%<RR<75%)and a poor group(RR<50%).Correlations between the surgical outcome and various factors,such as age.sex,body mass index,chronic disease,intraoperative data and imaging observations.were analyzed by statistical method2.The TOLF score consists of 5 components,namely,the age at surgery(1-3 points),diabetes mellitus(1 point),preoperative duration of symptoms(1-2 points).spinal canal axial remnant area ratio(0-2 points)and intramedullary signal change on MRI(Magnetic Resonance Imaging,MRI)(1 point).The scores of all patients were calculated and analyzed for their correlation with the postoperative recovery ratio.In addition,intraoperative blood loss,urinary catheter indwelling time,cerebrospinal fluid leakage and postoperative neurologic deterioration were also measuredResults:1.A total of 64 patients were included.Statistical analysis showed that age.diabetes,preoperative duration of symptoms,spinal canal axial remnant area ratio and intramedullary signal change on MRI were associated with postoperative recovery ratio2.The mean TOLF score at the final follow-up was 4.6 points in the excellent group(20 patients).5.0 points in the good group(29 patients),and 7.3 points in the poor group(15 patients).A higher TOLF score predicts lower postoperative recovery ratio(P=0.000),longer urinary catheter indwelling time(P=0.023)and higher incidence of postoperative neurologic deterioration(P=0.000).However,no correlation was identified between the TOLF score and intraoperative blood loss(P=0.755)or cerebrospinal fluid leakage(P=0.911)Conclusions:The age.diabetes,preoperative duration of symptoms,spinal canal axial remnant area ratio and intramedullary signal change on MRI are important potential factors affecting postoperative recovery.The TOLF score is a novel and rudimentary scoring system that describes the predictive factors that indicate the postoperative prognosis of thoracic ossification of the ligamentum flavum.