Clinical Application Of Cement-augmented Percutaneous Pedicle Screw Instrumentation And Analysis Of Leakage Factors

BACKGRAND:With excellent correction and fixation capabilities,pedicle screws system,which penetrate the anterior,middle and posterior columns of the spine,has long been the gold standard treatment for posterior spinal internal fixation.Compared with open screw placement,percutaneous pedicle screw fixation is a more minimally invasive and effective treatment method that provides the same stability with less surgical trauma and is clinically suitable for the majority of patients.However,with the remarkably increasing aged tendency of popullation,more and more patients were suffered from osteoporotic thoracolumbar diseases occurrence of screw loosening or poll-out after internal fixation were also increased because of the reduction of bone density.Cement-augmented pedicle screw instrumentation has long been proved to be effective in improving the anchorage performance of screws in the vertebral body,and leakage of bone cement is one of the common complications of this technique.OBJECTIVE:The purpose of this study was to investigate the related factors of bone cement leakage in the clinical application of cement-augmented percutaneous pedicle screw instrumentation,and to evaluate the safety and preliminary clinical efficacy of this treatment.METHODS:A total of 45 patients,including 19 males(42.22%)and 26 females(57.78%),underwent cement-augmented percutaneous pedicle screw instrumentation in the first affiliated hospital of Guangzhou medical university from January 2017 to December 2019 were retrospectively analyzed.The average age was(68.11±8.78)years from 47 to 89 years old.The body mass index(BMI)ranged from 16.81 to 33.25,with an average of(23.74±3.74).The bone mineral density(BMD)T value ranged from-2.50 to-3.87,averaging(-2.96±0.41).All patients were evaluated for preoperative and postoperative pain severity and dysfunction using the Visual Analogy of Back pain and Lim Pain Scale and the Oswestry Functional Index.The leakage of cement and the type of leakage were judged and counted by the results of postoperative CT scan,and the position of screw implantation(screw implantation depth,the distance between screw tip and midline of vertebral body)was measured.The postoperative screw loosening was evaluated by postoperative X-ray and CT scan.Measurement data was expressed in the form of mean ±standard deviation,and qualitative data was expressed in the form of percentage "%".The effectiveness of surgical was analyzed by paired sample T test.The related factors of bone cement leakage were analyzed by Logistic regression analysis and compared with relevant literature.RESULTS:In this study,45 patients underwent successful surgery,and the mean follow-up time was 15.02±4.33 months.A total of 228 pedicle screws were used and 221 screws were augmented.The number of leakage screws was 36 cases(16.29%),and the types of leakage were: B-type leakage(23cases,10.41%),S-type leakage(8cases,3.62%),and C-type leakage(4 cases,1.81%),both B-type and S-type leakage was found in a same patient(0.45%)screw had both B-type and S-type bone cement classification.The Visual Analogy of Back pain and Lim Pain Scale and the Oswestry Functional Index after surgery were significantly lower than those before surgery(P<0.01),furhter more,there was no significant difference between the above indexes in the last follow-up and those on7 d after surgery(P>0.05).Until the last follow-up,only 1 case was found to have screw breaking in the vertebral body,and no loosening or pull-out was found in other cases.No internal fixation failure requiring revision treatment was found.There were no postoperative complications such as infection,pulmonary embolism and nerve compression related to cement leakage.For the overall factor analysis of patients: in the univariate binary logistic regression analysis,‘BMD’ and ‘the number of screws’ are the influencing factors of bone cement leakage.In order to further clarify the influence of multiple factors on bone cement leakage,the P≤0.10 factor in the single-factor logistic regression analysis was selected for the multi-factor logistic regression analysis,which showed that ‘BMD’ was the influencing factor of bone cement leakage.For the analysis of screw implantation: both univariate and multivariate binary logistic regression analyses found that ‘the distance between the screw tip and midline of vertebral body’ and ‘the depth of the screw’ were the influencing factors of bone cement leakage.Multivariate logistic regression analysis showed that ‘the depth of the screw’ was the influencing factor of B-type leakage,while‘the distance between the screw tip and midline of vertebral body’ is the influencing factor of S-type leakage.No statistically significant influencing factors were found for C-type leakage.CONCLUSION:1.The application of cement-augmented percutaneous pedicle screw instrumentation in the treatment of osteoporosis patients with thoracolumbar diseases is a safe and effective measure,with reliable fixation and less complications caused by leakage.2.In the use of cement-augmented percutaneous pedicle screws,the occurrence of bone cement leakage is also related to a variety of other factors,such as bone mineral density of patients,the number of reinforced screws,the depth of screw implantation,the distance between the screw tip and midline of vertebral body,in the case of appropriate timing and dosage of bone cement injection.3.The surgeon should master the vertebral structure,make a detailed evaluation of the patient’s condition before surgery,improve the accuracy of percutaneous screw placement,choose a reasonable screw position and develop an individual application plan of bone cement to reduce the risk of bone cement leakage.