BACKGROUND: Atlantoaxial posterior approach is currently the main surgical treatment for atlantoaxial instability and/or dislocation, but the shape of rod in normal screw-rod device system is cylindrical. To obtain satisfactory reduction of atlantoaxis, the rod will be pre-bent obviously before fixation; however, the cylindrical rod will be rotated when tighten the nuts. Extra devices will be required to adjust and maintain the direction of the rod, thereafter, the surgical field will be blocked by the device, and spinal injury will occur once the devices are not held tightly. While the novel automatic anti-rotation rod has the function of anti-rotation during nut-tightening process, and also holds all the advantages of normal rod. Further research should be performed for the differences in biomechanical characteristics between two methods.OBJECTIVE: To investigate the biomechanical properties of the novel automatic anti-rotation rod for internal fixation system of atlantoaxial posterior approach based on three-dimensional finite-analysis model of upper cervical spine.METHODS: The three-dimensional finite element model of upper cervical spine with internal rod fixation system was developed. The biomechanical characteristics of the internal fixation system were analyzed. RESULTS AND CONCLUSION: The traditional and novel three-dimensional finite element model with realistic and geometric similarity contained 198330 elements, 964747 nodes and 246788 elements, 996069 nodes,correspondingly. There was no obvious stress concentration in both two systems, stress was concentrated mainly in the screw-bone and screw-rod interfaces. The stress values of the novel system were higher than those of the traditional system, but the maximum Von Misses Stress of two systems was lower than the yield (795-827 MPa ) and ultimate (860-896 MPa) strength of titanium alloys. These results show that the design of the novel automatic anti-rotation rod-screw fixation system has matched the biomechanical requirements for new internal fixation instruments, and is one safe, effective and practical device for atlantoaxial posterior procedure showing promising application prospect.

Objective:To perform the preoperative design and operative simulation for periprosthetic femoral fractures (PFF)in one patient with complex tumor knee replacement under assistance of three-dimensional (3D) printing technology,and to explore a more accurate and feasible way to restore the normal anatomy and function of this kind of patients.Methods:The female patient aged 32 years old diagnosed with PFF after an complex tumor knee replacement was selected.The CT images of the patient’s bilateral legs were collected and reconstructed.The bilateral femurs were virtually sliced and the important parameters at each location of both sides were recorded respectively.Novel femoral stem and nail paths were specially designed on the basis of original prosthesis according to these parameters. Then vitual assemble was made with the residual femur. The prosthetic femoral stem components and navigator were customized based on the 3D simulation results when no more errors were found.The residual femoral resin model,customized components and navigator were printed with an SLA 3D printer.The bone cement was taken out and newly designed femoral stem was implanted successfully according to the steps designed preoperatively.The preconcerted allograft bone plates were applied for patch of the bone defect.The pathological results,X-ray and functional scores were included in the observation indexes. Results: With the help of successfully preoperative computer matching,successfully printed bone model-prosthesis assemble and re-customized navigator,the operation was successfully performed.The postoperative alignment shown in the X-ray image was good.The patient was able to normally walk and squat one month after operation with a crutch.MSTS93 score was improved from 0 before operation to 14 only one month after operation.Conclusion:As for PFF of complex tumor knee joint,preoperative design and simulation with 3D printing technology may provide a more accurately and effectively operative outcome than traditional methods.

In order to support study of new radiofrequency ablation treatments and finally realize of precise conformal ablation of targeted tissue, this paper proposed a system which is able to generate radio frequency currents at different frequencies. The designed system bases on the basic principle of Class E power amplifier and uses MSP430 microcontroller as a controller and uses a touch screen as human-machine interface to design a frequency-selectable radiofrequency ablation treatment system,. The RF signals at frequencies of 230 kHz, 460 kHz, 920 kHz, and 2 000 kHz were tested to verify the feasibility of the system, and by using a tissue phantom, tested the heating ability of the RF signals at frequencies of 460 kHz, 920 kHz, and 2 000 kHz. The results show the device could well heat the tissue at the three frequencies. The study has also found that both the highest temperature and the ablation area decreases with RF frequency, when using the constant power control mode.
Catheter Ablation ; instrumentation ; Hot Temperature ; Humans ; Hyperthermia, Induced ; Phantoms, Imaging ; Radio Waves

Objective:To investigate the metal artifact reduction effect of orthopedic metal artifact reduction (O-MAR) techonology and its improvement effect on the image quality in CT examination in the patients with arthroplasty, and to elaborate the significance of the technology in clinical diagnosis and treatment of arthroplasty.Methods:The CT data of 20patients with hip or knee prostheses was collected.There were two tube voltages in each group of CT data:120and 140Kev.There were also two groups of CT data in each tube voltage group:nonO-MAR group and O-MAR group;there were four subgroups of CT data of each case:120 Kev/-O-MAR, 120Kev/+O-MAR, 140Kev/-O-MAR, 140Kev/+O-MAR.After data collection, Mimics software was applied to conduct three-dimensional (3D) reconstruction for purpose of the qualitative and quantitative analysis of CT data.Qualitative analysis mainly included the grade of severity of metal artifact and quality of data.Quantitative analysis included the volume of metal artifact, the average CT value and standard deviation (SD) in region of interest (ROI) .ROI 1and ROI 2were chosen at the location of beam hardening artifact (radial high-density metal artifact) and photon starvation artifact (band low-density metal artifact) , respectively.Results:According to the result of3D measurement, the volumes of artifact had no significant difference between 120 Kev/-O-MAR group and140Kev/-O-MAR group (P=0.062) , but there were siginificant differences in the volumes of artifact between other groups (P＜0.05) ;O-MAR technology decreased the volume of beam-hardening artifact obviously (P＜0.05) .According to the results of two-dimensional (2D) measurement, there was no significant difference in the average CT values in ROI 2between 120Kev/-O-MAR group and 140Kev/-O-MAR group (P=0.069) , but there were significant differences in the average CT values between other groups (P＜0.05) ;O-MAR technology decreased the high-density beam-hardening metal artifact and the low-density photon-starvation metal artifact in 2D measurement.Conclusion:O-MAR technology could significantly reduce the CT metal artifact of hip and knee prostheses and increase the clinical value of CT data.

In order to solve the heat transfer mechanism in radiofrequency treatment of atherosclerosis, we design two experimental structures to simulate the plaque, and use three frequencies and a variety of electrode arrangement, to study the heat transfer mechanism and heating capacity under the special structure. The results show that the temperature increment and heating area increase with increasing frequency. Under the structure in which the lipid particles are embedded in the fiber cap, using three electrodes with opposite polar arrangement between middle electrode and others, achieves effective heating to lipid pool in the plaque.

This study aims to develop an independent control system for radiofrequency electrode arrays,intended for the conformal ablation of unwanted tissues.Unlike traditional single radiofrequency voltage applications,this study employs high-frequency transformer isolation and radiofrequency load matching technologies to divide the radiofrequency signal source into eight independent groups.Each group operates at the same phase and frequency but with different voltage values.Experimental results indicate that the designed system can independently output various combinations of radiofrequency signals.The actual output voltage has a relative error controlled within 6%,the frequency error is less than 0.5%,and the phase difference among the groups is less than 1°.In the biomimetic tissue heating experiments,it is found that by controlling the voltage of each electrode within the electrode array,ablation of different shapes can be achieved,and the ablation depth is positively correlated with the applied radiofrequency voltage.

Objective:To discuss the accuracy of stereolithography (SLA)-3D printing model in orthopedics and maxillofacial surgery,and to clarify the reliability of its clinical application.Methods:A total of 33 cases of SLA-3D printing models were randomly included (10 long bones,13 irregular bones and 10 prostheses),and the CT scanning and three-dimensional reconstruction were performed.According to the clinical application characteristics of the models,the max height (MH),max length (ML),max width (MW),width of the trochlear (WT),length of the trochlear (LT),length of the glenoid cavity (LGC),width of the glenoid cavity (WGC),distance of pubic tubercle-anterior superior iliac spine (DPI),diameter of the acetabulum (DA),diameter of the marrow cavity (DMC),anterior height of right ramus (AHRR) and posterior height of right ramus (PHRR) were selected to measure the original data and model data,respectively.The absolute / relative errors were calculated.Intraclass correlation coefficient (ICC) was used to evaluate the consistency of the data.The three-dimensional error analysis of the prosthesis model was carried out.Results:There were no significant differences in the anatomical parameters except MW of irregular bone (P＞0.05) in 33 cases of SLA-3D printing model.The values of ICC were all greater than 0.950;the maximum values of absolute / relative errors were-0.58 mm and-1.37％,respectively;the maximum 3D error of prosthesis model was 0.237 mm,and the average value was 0.132 mm.Conclusion:The CT data of SLA-3D model is highly consistent with the original data,and it is accurate and reliable in the diagnosis and treatment of the diseases in orthopedics and maxillofacial surgery.

Objective:To subdivide clinical classification of refractory atlantoaxial dislocation, and evaluate the reliability of new subdivide clinical classification of refractory atlantoaxial dislocation.Methods:From January 2010 to December 2018, 48 patients with refractory atlantoaxial dislocation were treated, including 19 males and 29 females, aged 16 to 65 years, with an average of 39.2±13.3 years. According to the changes of relative anatomical position of C 1 and C 2 under general anesthesia with heavy traction of 1/6 body weight, subdivide clinical classification of refractory atlantoaxial dislocation were proposed, and refractory atlantoaxial dislocation was divided into traction loosening type (atlantoaxial angle≥5°) and traction stabilization type (atlantoaxial angle<5°). The traction loosening type was directly reduced by posterior atlantoaxial screw-rod fixation and fusion without anterior or posterior soft tissue release. For traction stabilization type, transoral soft tissue release was performed first, and then transoral anterior reduction plate fixation and fusion or posterior atlantoaxial screw-rod fixation and fusion were performed. Atlantodental interval (ADI) and atlantoaxial angle (AAA) were measured and collected before and after surgery to evaluate atlantoaxial reduction. The space available for the spinal cord (SAC) were measured to evaluate spinal cord compression. Visual analogue score (VAS) was used to evaluate the neck pain levels, and Japanese Orthopaedic Association (JOA) scores was used to evaluate the neurological function. American Spinal Cord Injury Association impairment scale (AIS) was used to evaluate the degree of spinal cord injury. One week, 3, 6, 12 months postoperatively and the annual review of the X-ray and CT scan were checked, in order to evaluate the reduction, internal fixation and bone graft fusion. Results:Among all 48 cases, 22 cases were traction loosening type, of which posterior atlantoaxial screw-rod fixation and fusion were performed in 16 cases and occipitocervical fixation and fusion in 6 cases. 26 cases were traction stabilization type, and they all underwent anterior transoral release, and then, anterior TARP fixation and fusion were performed in 24 cases and posterior screw-rod fixation and fusion in the other 2 cases. X-ray, CT and MRI images and of all patients 1 week after surgery showed good atlantoaxial reduction and decompression of spinal cord. In each of the two types, there was one case lost to follow-up. For 46 cases in follow-up, the follow-up time ranged from 6 to 72 months, with an average of 38.0±17.2 months. Among 46 cases, 21 cases of traction loosening type showed that, ADI reduced from preoperative 9.9±2.2 mm to 2.3±0.9 mm at 3 months after surgery and 2.3±1.0 mm at the last follow-up, AAA increased from preoperative 57.9°±12.3° to 91.0°±2.2° at 3 months after surgery and 90.9°±2.2° at the last follow-up, SAC increased from preoperative 9.8±1.3 mm to 15.1±0.7 mm at 3 months after surgery and 14.9±0.7 mm at the last follow-up, VAS score reduced from preoperative 1.5±2.1 to 0.7±1.0 at 3 months after surgery and 0.3±0.6 at the last follow-up, and JOA score increased from preoperative 10.2±1.7 to 13.3±1.3 at 3 months after surgery and 14.9±1.5 at the last follow-up. Twenty-five cases of traction stabilization type presented that, ADI reduced from preoperative 9.7±2.0 mm to 2.1±1.4 mm at 3 months after surgery and 2.1±1.3 mm at the last follow-up, AAA increased from preoperative 55.8°±9.2° to 90.9°±1.4° at 3 months after surgery and 90.9°±1.3° at the last follow-up, SAC increased from preoperative 10.5±1.0 mm to 15.4±0.5 mm at 3 months after surgery and 14.8±2.8 mm at the last follow-up, VAS score reduced from preoperative 1.7±2.1 to 0.7±0.9 at 3 months after surgery and 0.3±0.5 at the last follow-up, and JOA score increased from preoperative 10.1±1.3 to 12.9±1.5 at 3 months after surgery and 14.4±1.3 at the last follow-up. In the traction loosening type, all the 10 grade D patients were improved to grade E at the last follow-up. In the 2 grade C patients of traction stabilization type before surgery, 1 patient was improved to grade E, 1 patient was improved to grade D, and all 11 patients with grade D were improved to grade E at the last follow-up. Bony fusion was obtained in all patients from 3 to 6 months, with an average of 4.4±1.5 months. During follow-up period, no looseness of internal fixation or redislocation happened.Conclusion:Refractory atlantoaxial dislocation can be divided into traction loosening type and traction stabilization type. For traction loosening type, satisfactory reduction can be achieved by using posterior atlantoaxial screw-rod system without soft tissue release. For traction stabilization type, anterior release is preferable, and then anterior TARP or posterior screw-rod can be used to achieve satisfactory reduction.

Objective To investigate the clinical effect of posterior screw-rod fixation fusion for the treatment of atlantoaxial dislocation due to rheumatoid arthritis.Methods From January 2011 to December 2015,15 patients with atlantoaxial dislocation due to rheumatoid arthritis were treated,including 6 males and 9 females,aged 35 to 75 years (mean 55 years).All cases were evaluated about the difficulty of relocation by extension-flexion X-ray and treated with posterior screw-rod reduction,fixation and autogenous bone grafting under general anesthesia.Atlantodental interval (ADI) was measured and collected before and after surgery.Visual Analogue Scale/Score (VAS),American Spinal Cord Injury Association (ASIA) and Japanese Orthopaedic Association (JOA) scores were comprehensively used to evaluate the clinical effect.1 week,3,6,12 months postoperatively and the annual review of the X-ray and CT were checked,in order to evaluate the reduction,internal fixation and bone graft fusion.Results All patients were reducible dislocation and successfully performed the posterior screw-rod fixation fusion surgery.The patients were followed up for 3 to 24 months (average,15 months).Atlantoaxial solid bony fusion was obtained from 3 to 6 months.ADI reduced from preoperative 6.3±1.7 mm to postoperative 2.2±0.8 mm,VAS score reduced from preoperative 5.4±2.7 to postoperative 1.7±1.0,ASIA motor score improved from preoperative 82.3±15.6 to 95.3±4.5 at 6 months after the surgery,JOA score increased from preoperative 13.8±2.9 to 15.5±1.4 at 6 months after the surgery,and the statistical significance was revealed between preoperation and postoperation.Nine cases were in D grade of ASIA,3 cases improved from D to E grade after surgery,2 cases reached E grade in the other 6 cases after 6 months,2 cases recovered to E grade after 12 months and other 2 cases in D grade got uniformity after surgery.Well internal fixation and no redislocation were found on X-ray and CT during follow-up period.Conclusion Atlantoaxial dislocation because of rheumatoid arthritis was numerously reducible genre.Posterior screw-rod fixation and autogenous bone grafting can gain satisfying clinical efficacy.

According to the actual requirements of pediatric intensive care, a suction detection system of pediatric oral secretions integrated with monitoring function is designed. The system has the function of adjustable intermittent attraction. The duration and proportion of intermittent attraction can be adjusted according to the individualized needs of pediatric intensive care. The suction head of pacifier can reduce the mechanical damage to pediatric oral mucosa as much as possible. Meanwhile, the system can detect and monitor the real-time biochemical indexes of the collected oral secretions, which can be used to help the judgement of aspiration and quantitatively evaluate the microcirculation dysfunction.
Bodily Secretions ; Child ; Humans ; Mouth ; Suction/instrumentation*