| Objectives:The incidence of vertebral metastasis in patients with advanced malignant tumors is about 50%to 70%,and about half of the patients may have vertebral body destruction.At present,the main intervention method for patients with metastatic tumors with vertebral body destruction is Percutaneous Vertebroplasty(PVP),that is,under the guidance of images,bone cement is injected into the vertebral body to ensure the stability of the vertebral body.However,in patients with incomplete posterior edge of the vertebral body,bone cement is likely to leak into the spinal cord cavity through the posterior edge of the vertebral body during PVP treatment,causing serious damage to the spinal cord and even death of the patient.Previous studies have shown that when thermal ablation,such as radiofrequency ablation(RFA)or microwave ablation,is used to treat other tumors,intraoperative real-time imaging examinations found that a layer of low-density bands or ground-glass-like changed fine structures formed around the tumor.This suggests that after thermal ablation of vertebral metastases,a low-density zone,that is,a biofilm barrier,can also be formed around the vertebral metastases.Whether this biomembrane barrier has the potential to block the extravasation of bone cement,the combination of RFA and PVP therapy can achieve better curative effects.To verify this hypothesis,this experiment constructed an animal model of destruction of the posterior edge of the vertebral body,using imaging and pathological examinations to confirm the existence of the biofilm barrier after ablation of vertebral metastases,and to explore whether this layer of biofilm barrier can prevent it.Bone cement leaks into the spinal canal,thereby reducing damage to the spinal cord,and comparing the differences in postoperative survival between different groups,confirming the feasibility,safety and efficacy of RFA combined with PVP in the treatment of vertebral metastases with damage to the posterior edge of the vertebral body.In addition,this experiment collected some patients with vertebral metastasis and divided them into a simple PVP group and a PVP combined with RFA group.By comparing the differences in the degree of bone cement leakage between the two groups,it was verified that the clinical efficacy of RFA combined with PVP which was used to treat the posterior edge of the vertebral body destruction with vertebral metastases.Methods:Animal information:70 healthy New Zealand white rabbits(Jinan Xilingjiao Biotechnology Co.,Ltd.),male,weighing 3.0-3.5kg.Under CT guidance,60 animal models of rabbit vertebral body destruction caused by VX2 metastasis(Beijing Beina Chuanglian Biotechnology Research Institute)were constructed,and they were randomly divided into 4 groups,15 in each group,group A(RFA combined with PVP group));Group B(PVP-only group);Group C(RFA-only group);Group D(blank control group).CT and MRI examinations were performed at the 3rd and 4th weeks after the operation,and the imaging confirmed that the animal was inoculated with bone discontinuity in the posterior edge of the vertebral body,indicating that the modeling was successful.Animal records and follow-up items:①In the process of microwave ablation(RFA)for vertebral metastases,real-time CT scans are used to determine whether there is a low-density zone around tumor ablation;②Different groups of animals are observed during vertebroplasty Bone cement leakage;③Using pathological and immunohistochemical detection methods,detect whether there is a biofilm barrier on the edge of the tumor after ablation,and observe the leakage of bone cement into the vertebral body;④Statistics and analysis of the remaining rabbits Differences in group survival.2.Clinical data:The clinical study is a retrospective study,collecting 45 patients with vertebral body metastasis and vertebral body destruction admitted to the Second Hospital of Shandong University from January 2017 to January 2021.All patients strictly followed the inclusion and exclusion criteria.Among them,25 patients received PVP therapy(PVP group),and 20 patients received RFA combined with PVP therapy(RFA+PVP group).Main records and follow-up clinical items:①The patient’s clinical data and details of the primary disease;②The preoperative and postoperative visual analog scale(VAS)and functional status evaluation(KPS)score changes in different groups of patients;③The degree of bone cement leakage in different groups of patients.Animal study data analysis was performed using SPSS 24.0 software and Image J.The results were expressed as mean±standard deviation(x±s).The overall difference between each group was tested by independent sample t test.P<0.05 considered the difference to be statistically significant.The clinical data were statistically processed using SPSS 24.0 software.It accords with the normal distribution and the variance is uniform,then it is expressed as the mean±standard deviation(x±s),and the comparison between the two groups is carried out by t-test.The data of continuous variables that do not conform to the normal distribution and the homogeneity of variance are represented by the median(interquartile range),and the Wilcoxon rank sum test is used for comparison.Results:The success rate of operation in the 4 groups of animal experiments was 100%(15/15).CT scans of groups A and C showed a low-density zone around the tumor ablation.Postoperative pathology and immunohistochemical tests confirmed that this low-density zone had a biofilm barrier function.The bone cement leakage rate in group B was 100%,and the bone cement leakage rate in group A was 20%.The difference between the two groups was statistically significant(P<0.05);the average postoperative survival time of group A was 16.72±0.93 days.The average postoperative survival time of group B was 7.26±0.75 days,the average postoperative survival time of group C was 7.80±1.30 days,and the average postoperative survival time of group D was 3.84±1.24 days.The postoperative survival time of group A was significantly different from the other three groups(P<0.05).In addition,compared with group D,the postoperative survival time of group B and group C were different(P<0.05).However,the difference between group B and group C was not significant(P=0.27).Clinical materials showed that the PVP group and the combined percutaneous vertebroplasty after radiofrequency ablation(RFA+PVP group)had different degrees of bone cement extravasation.There were 8 cases of bone cement extravasation in the PVP group,with a percentage rate of 32%.The RFA+PVP group had bone cement extravasation.There was 1 case outside of cement,the percentage rate was 5%,there was a significant statistical difference between the two groups(P<0.05).The visual analog scale(VAS)was used to measure the preoperative and postoperative pain scores of the PVP group.The average preoperative VAS score was 5(4-6),and the postoperative VAS score was 2(1-2).The change between preoperative and postoperative is obvious,showing a significant statistical difference(P<0.01).Percutaneous pyramidal plasty combined with radiofrequency ablation(PVP+RFA group):preoperative VAS score was 5(4～6),postoperative VAS score was 2(1.25～3),P<0.01,and the PVP+RFA group also showed significant statistical differences,which was similar with the PVP group.Functional status evaluation(KPS)can be used to evaluate the function of cancer patients.Both groups were compared before operation and 1 month after operation.The average preoperative KPS score in PVP group was 60(55～70),and the average postoperative KPS score was 80(70～90).The preoperative and postoperative changes were large and P<0.01,showing significant statistical differences.Percutaneous pyramidal plasty combined with radiofrequency ablation(PVP+RFA group):preoperative KPS score is 60(50～68.75),postoperative KPS score is 80(62.5～90),similar to PVP group,also showing obvious statistical difference.Conclusion:Our animal experimental data preliminarily concluded that after RFA,a dense biofilm barrier can be formed at the edge of tumor ablation,which can prevent the leakage of bone cement into the spinal canal and reduce the damage of bone cement to the spinal cord.Clinical data show that RFA+PVP can significantly reduce the leakage rate of bone cement,and it is statistically significant.Therefore,RFA combined with PVP therapy has great clinical significance for tumor patients with vertebral body destruction. |
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