BACKGROUND:Currently,pedicle screw fixation technology is recognized as the gold standard for lumbar posterior fusion surgery.However,this technique is associated with several complications such as suboptimal screw placement,loosening,and fracture.Addressing these issues,it requires a thorough investigation into the mechanical properties of screw reinsertion to optimize surgical procedures and enhance success rates and safety.OBJECTIVE:By combining finite element analysis with biomechanical experiments,this study aims to compare and analyze the mechanical performance of traditional trajectory pedicle screws during multiple extraction processes.The goal is to reveal patterns in screw extraction strength over repeated withdrawals,providing scientific insights into the safety and effectiveness of pedicle screw reinsertion for clinicians.METHODS:Based on CT scan data,a three-dimensional reconstruction of the L4 vertebra model was performed.Three-dimensional printing technology was used to create biological experimental samples.A pull-out experiment was conducted according to a screw placement plan.Utilizing CT data and standard pedicle screw parameters,a finite element model of the L4 vertebra and a pedicle screw model(diameter 6.0 mm,length 45 mm)were established.The model was divided into five operating conditions based on screw placement angle and cycles.A finite element model was developed to simulate axial pull-out testing,analyzing stress distribution in the vertebral body and maximum axial pull-out strength of the screw.Mechanics experimental results of three-dimensional printing were compared and analyzed against simulation outcomes.RESULTS AND CONCLUSION:(1)A dedicated experimental setup for pedicle screw extraction from single vertebrae was designed and constructed.(2)In the three-dimensional printing experiment,our groups of models were compared between correctly placed screws and once improperly placed screws.The correctly placed screws group exhibited a maximum pull-out force of(1 422.63±23.80)N.Furthermore,with increasing deviation angles in screw placement,the maximum pull-out forces of each group gradually decreased.(3)Comparing the condition of a single improper nail placement with repositioning the nail correctly,when the offset angle of the improper placement exceeded that of Model 3,correctly repositioning the nail helps to increase the screw's pull-out resistance.(4)Comparing the scenario of two consecutive improper nail placements with repositioning correctly after two improper placements,correctly repositioning the nail reduced the screw's pull-out resistance.Without replacing the screw,it was not advisable to attempt a third nail placement.(5)Experimental pull-out strength of three-dimensional printing correlates significantly with finite element simulation results,with a correlation coefficient of 0.98.There is no significant difference in the outcomes between the two methods(P＞0.05).

BACKGROUND:Currently,pedicle screw fixation technology is recognized as the gold standard for lumbar posterior fusion surgery.However,this technique is associated with several complications such as suboptimal screw placement,loosening,and fracture.Addressing these issues,it requires a thorough investigation into the mechanical properties of screw reinsertion to optimize surgical procedures and enhance success rates and safety.OBJECTIVE:By combining finite element analysis with biomechanical experiments,this study aims to compare and analyze the mechanical performance of traditional trajectory pedicle screws during multiple extraction processes.The goal is to reveal patterns in screw extraction strength over repeated withdrawals,providing scientific insights into the safety and effectiveness of pedicle screw reinsertion for clinicians.METHODS:Based on CT scan data,a three-dimensional reconstruction of the L4 vertebra model was performed.Three-dimensional printing technology was used to create biological experimental samples.A pull-out experiment was conducted according to a screw placement plan.Utilizing CT data and standard pedicle screw parameters,a finite element model of the L4 vertebra and a pedicle screw model(diameter 6.0 mm,length 45 mm)were established.The model was divided into five operating conditions based on screw placement angle and cycles.A finite element model was developed to simulate axial pull-out testing,analyzing stress distribution in the vertebral body and maximum axial pull-out strength of the screw.Mechanics experimental results of three-dimensional printing were compared and analyzed against simulation outcomes.RESULTS AND CONCLUSION:(1)A dedicated experimental setup for pedicle screw extraction from single vertebrae was designed and constructed.(2)In the three-dimensional printing experiment,our groups of models were compared between correctly placed screws and once improperly placed screws.The correctly placed screws group exhibited a maximum pull-out force of(1 422.63±23.80)N.Furthermore,with increasing deviation angles in screw placement,the maximum pull-out forces of each group gradually decreased.(3)Comparing the condition of a single improper nail placement with repositioning the nail correctly,when the offset angle of the improper placement exceeded that of Model 3,correctly repositioning the nail helps to increase the screw's pull-out resistance.(4)Comparing the scenario of two consecutive improper nail placements with repositioning correctly after two improper placements,correctly repositioning the nail reduced the screw's pull-out resistance.Without replacing the screw,it was not advisable to attempt a third nail placement.(5)Experimental pull-out strength of three-dimensional printing correlates significantly with finite element simulation results,with a correlation coefficient of 0.98.There is no significant difference in the outcomes between the two methods(P＞0.05).

Objective This study was conducted to analyze the clinical characteristics and pituitary function of patients with primary empty sella (PES).Methods The clinical data from 123 hospitalized adult patients with PES from January 2010 to May 2016 were retrospectively studied.Results (1) The average age of the 123 (male 43,female 80) PES patients was (59.2 ± 13.6) years (ranging 24-92 years),among whom 61％ patients were in the age group between 50-69 years.(2) The symptoms of the patients included fatigue (56.1％),headache (34.1％),nausea and vomiting (17.9％),gonadal dysfunction (17.1％),visual disturbance (5.7％) and hypopituitarism crisis (3.3％).(3) Hypopituitarism was found in 66 of the 123 patients.Among them,36.6％,31.7％ and 17.1％ were central hypoadrenalism,hypogonadism,and hypothyroidism,respectively.The percentage of hypopituitarism in complete PES was significantly higher than that in partial PES (P ＜ 0.05).(4) Sixteen patients were concomitant with other autoimmune diseases including 11 patients with Graves' disease and 2 with Cushing's syndrome due to adrenal adenoma.Conclusions The incidence of hypopituitarism in PES was 53.7％,in which the pituitary-adrenal axis hypofunction was more common.An overall evaluation of the pituitary function was essential for the patients who had headache and fatigue,or with suspected PES.The patients with hypopituitarism should be given hormone replacement therapy in time and followed up afterword.

Objective The absorbable haemostatic membrane was used to stop bleeding during posterior spinal surgery so as to investigate the therapeutic effect and the security of the absorbable haemostatic membrane. Methods Ninety-four patients were enrolled into the experimental group and the control group. In the experimental group , the decompression wound is handled by using the regular absorbable haemostatic membrane to stop bleeding. In the control group , the conventional surgical methods , such as coagulation , brain cotton and other methods were used to stop bleeding. After the operations , patients in two groups were given indwelling vacuum drainage tube. The post operation vacuum pipe drainage , the drainage tube removing time , the incidence of postoperative complications after removing drainage tubes , the reoperation number , vital signs after 24 hour (temperature, respiration, pulse, blood pressure), and laboratory tests (blood count, coagulation function parameters) were determined and compared between two groups. Results Both the vacuum drainage at 24 hours post operation and the total vacuum drainage post operation were significantly reduced in the experimental group(P < 0.05, respectively). No significant differences in the coagulation function parameters were found between both two groups. Conclusion The absorbable haemostatic membrane may be applicable for spinal surgery.

[Summary] Vitamin D is one of the fat-soluble vitamins which,eventually through activation in the liver and kidneys within the human body,becomes an important hormone——1,25-dihydroxyvitamin D3.Not only may 1,25dihydroxyvitamin D3 promote calcium and phosphate absorption by the intestine,but also stimulate the macrophages to secrete a protein(cathelicidin) which is able to digest the microbacterias,including viruses and bacteria,playing an antiinfective effects.Theofore,a proper supplementation of vitamin D would be beneficial for human health.

Multiple myeloma is common in the older population and is treated mainly with chemotherapy. However, chemotherapy-related side effects imitate the clinical manifestations of Sheehan's syndrome, which leads to misdiagnosis and missed diagnosis, particularly for older patients without a clear history of postpartum hemorrhage. Therefore, when older women with malignant myelomas show refractory hyponatremia and gastrointestinal disorders while under chemotherapy, a diagnosis of Sheehan's syndrome should be considered. The early detection of the disorder will guarantee timely individualized treatment.

Objective To assess the effects of artificial cordyceps sinensis(Jin shuibao) on the numbers of podocytes and epithelial-mesenchymal transition in diabetic rats.Methods Diabetes was induced by intraperitoneal injection of low dose streptozocin.Sprague-Dawley rats were randomly divided into three groups:control group (CON),diabetic model group(DM),and artificial cordyceps sinensis treatment group(CS).After intervention for 8 weeks,the numbers of podocytes were estimated hy immunohistochemistry.The expressions of nephrin,desmin,and monocyte chemoattractant protein-1 (MCP-1) were detected.Results Compared with control group,DM group showed significantly decreased podocyte numbers and nephrin mRNA,with increased desmin and MCP-1 levels(P＜0.05).While the numbers of podocytes and nephrin mRNA were increased,and the expressions of desmin and MCP-1 were decreased in CS group as compared with those in DM group (all P＜0.05).Conclusions Artificial cordyceps sinensis notably improves epithelial-mesenchymal transition of podocytes,and increases the number of podocytes in diabetic rats.

Objective To evaluate the effectiveness of a insulin regimen for the management of stress hyperglycemia induced by head injury.Methods Eighty patients (64 male, 16 female) admitted to the hospital within 24h after head injury were enrolled in the study. The age ranged from 16-75 yr. The patients were divided into 3 groups according to the numeric values of Glasgow Coma Scale (GCS) : group Ⅰ 0, the step Ⅲ was taken to maintain blood glucose at normal level using formula Ⅱ : the maintenance dose of insulin = (last blood glucose ? 18) / 150 U?h-1 .Results The blood glucose levels before anesthesia were (12 ? 7) mmol (group Ⅰ ), (9 ? 3) mmol (group Ⅱ ) and (8 ? 5) mmol (group Ⅲ ) . The differences between the two groups were significant ( P