Development Of T-shaped Electronic Conductivity Device And Preliminary Clinical Application Study

Background:With the population aging problem aggravated in recent years,the incidence of thoracolumbar compression fractures caused by severe osteoporosis has become increasingly high.The persistent low back pain,kyphosis and prolonged bed rest caused by thoracolumbar compression fractures and its complications such as deep vein thrombosis,and cardiopulmonary disease have badly affected the lives of patients.Percutaneous vertebroplasty(PVP)and percutaneous kyphoplasty(PKP)are the most widely-used minimally-invasive treatments for osteoporotic vertebral compression fracture(OVCF).However,PVP and PKP have some limitations such as the surgical difficulty,large radiation exposure,high risk of complications and the long learning curve.Therefore,it has become urgent to find effective measures to lower surgical difficulty of PVP/PKP,reduce intraoperative radiation,and shorten the learning curve for young spine surgeons.The key step and core technique of PVP are to make percutaneous puncture to reach the designated ideal vertebral region.Although various post-penetration bracing techniques are added to PKP,PKP still takes PVP puncture positioning as the core foundation.According to the findings of Chinese and overseas studies,safe and efficient puncture positioning methods include the bare-handed operation,template positioning,the combined X-ray and CT-image-guiding method,and the robot navigation method.Electrical Bioimpedance is an inherent physical property of biological tissues.With different compositions and structures,biological tissues have special electrical properties.Electrical bioimpedance measurement is a detection technique which can provide medical information on the physiological and pathological conditions of the human body based on the electrical properties of biological tissues.Existing research on electronic conductivity device mainly focuses on the channel-preparing process before the pedicle screw implantation in open surgery.As proved by many studies in China and other countries,it is a simple,safe,sensitive and effective method to use electronic conductivity device to detect vertebral pedicle perforation in open surgery.However,few reports have made on the application of electrical impedance technology in the minimally-invasive spine surgery.In this research,explorations were made to combine electrical bioimpedance technology with PVP/PKP to guarantee the safety and efficiency of percutaneous vertebroplasty.Objective:The present study aimed to measure the electrical bioimpedance of tissues in the spinal surgical area,determine the appropriate electrical parameters for spine surgery,design and develop an electronic conductivity device for PVP/PKP surgery,and check the effectiveness of the electronic conductivity device in PVP surgery.Methods:This study was based on electrical bioimpedance theory.First of all,the study makes animal experiments to measure the pedicle parameters of fresh porcine vertebra.The measurement data of the animal experiments was consistent with the findings of relevant Chinese and international studies and similar to the reported pedicle parameters of human vertebra.On this basis,a concentric-axis probe was designed and used to measure the change in electrical bioimpedance of the porcine vertebra,to check its validity and obtain a safe range.Secondly,the electrical bioimpedance of human vertebra was also measured to get a reference interval.According to the human electrical bioimpedance data,a "T-shaped"electroinc conductivity device(hereinafter referred to as "T-shaped" device)was designed for PVP.Lastly,the "T-shaped" device was used in preliminary research of clinical application,to test the effectiveness of this device in shortening the operation time and weakening the fluoroscopic radiation during PVP.Furthermore,the "T-shaped" device was also compared with the conventional free-hand method and the intraoperative CT scanning infrared receiving navigation device based on O-arm(hereinafter referred to as O-arm navigation).Results:① According to the results of the experimental research on electrical bioimpedance characteristics of the fresh porcine spine,20KHz～60KHz was an appropriate frequency range for measuring the electrical bioimpedance values of biological tissues.Beyond that,the change in the electrical bioimpedance values of cortical bone,cancellous bone,spinal cord and paravertebral muscle within this frequency range was relatively stable.Therefore,experimental research was performed to study the electrical bioimpedance values of the human spine,to get data on the electrical bioimpedance of different tissues in the spinal surgical area during PVP surgery.②Due to the particularity of spine surgery,especially the percutaneous minimally invasive surgery,electrode design is quite crucial.To be specific,it is essential to explore the influence of the electrode material and shape on the electrical bioimpedance value,and the requirements for the electrode size and mechanical strength in pedicle puncture.According to our exploration,the stainless steel coaxial electrode can not only meet the mechanical strength requirements of pedicle puncture,but also guarantee the stability of the electrical bioimpedance measurement.③ The AFE4300 chip was used to design a circuit system for measuring the impedance of human spine.After that,switching current circuit charging and discharging was adopted to inject safe current into spinal tissue.Moreover,the dielectric properties of different tissues in the spinal surgical area were based to effectively identify different tissues in the spinal surgery area.④The electrodes and circuit systems were integrated into a "T-shaped" device.The "T-shaped"device was applied to clinical PVP surgery to meet the operational needs and sterilization requirements,and compared with bare-handed operation and O-arm navigation system,respectively.Compared with the traditional bare-handed operation,the "T-shaped" device can largely reduce the number of times of fluoroscopy and shorten the puncture operation time in PVP.Compared with the O-arm navigation system,the "T-shaped" device has no significant difference in the puncture time,but has more times of fluoroscopy.However,the O-arm navigation system has limitations such as the damage of the reference frame fixation,the CT scanning time and data transmission and image reconstruction time of the intraoperative site,the acquisition cost,site-using conditions,and the increased radiation to patients and the surgeons.Thus it can be concluded that the T-shaped electrical impedance navigation device is superior to the O-arm navigation in PVP.Conclusion:The "T-shaped" device developed on the basis of electrical bioimpedance can help to identify different tissues in the spinal surgical area,thus guaranteeing safe,effective and stable percutaneous puncture to build correct pedicle channels during PVP.