Design and Manufacture of Bionic Porous Titanium Alloy Spinal Implant Based on Selective Laser Melting(SLM)

In order to meet the clinical requirements of spine surgery,this paper proposed the exploratory research of computer-aided design and selective laser melting(SLM)fabrication of a bionic porous titanium spine implant.The structural design of the spinal implant is based on CT scanning data to ensure correct matching,and the mechanical properties of the implant are verified by simulation analysis and laser selective melting experiment.The surface roughness of the spinal implant manufactured by SLM without post-processing is Ra 15μm,and the implant is precisely jointed with the photosensitive resin model of the upper and lower spine.The surface micro-hardness of the implant is HV 373,tensile strengthσ_(b)=1238.7 MPa,yield strengthσ_(0.2)=1043.9 MPa,the elongation is 6.43%,and the compressive strength of porous structure under 84.60%porosity is 184.09 MPa,which can meet the requirements of the reconstruction of stable spines.Compared with the traditional implant and intervertebral fusion cage,the bionic porous spinal implant has the advantages of accurate fit,porous bionic structure and recovery of patients,and the ion release experiment proved that implants manufactured by SLM are more suitable for clinical application after certain treatments.The elastic modulus of the sample is improved after heat treatment,mainly because the microstructure of the sample changes fromα’phase toα+βdual-phase after heat treatment.In addition,the design of high-quality bionic porous spinal implants still needs to be optimized for the actual needs of doctors.

Stress fractures in uncommon location:Six case reports and review of the literature

BACKGROUND Individuals’interest in sports activities has been increasing,contributing to more stress fracture occurrences in uncommon locations on the skeleton.In this study,several cases of stress fractures in atypical locations are presented,and the possibility of combining diagnostic methods to make accurate and quick diagnoses is explored.Additionally,different causes of stress fractures,as well as various modalities of treatment,are highlighted.Other potential factors of stress fractures were identified by a literature review.CASE SUMMARY Six cases of stress fractures in the calcaneus,intermediate cuneiform bone,sacrum,tibia(bilateral),navicular bone and femoral neck are presented,with different types of diagnostic imaging and treatments.All of the cases were associated with an aspect of mobility because all of the patients were physically active in various sport disciplines.CONCLUSION The type of therapeutic procedure selected should depend on the specific clinical case,i.e.,the patient’s condition and level of physical activity.

X-ray DIAGNOSIS OF JUXTACORTICAL CHONDROSARCOMA (A REPORT OF 16 CASES)

The clinical and radiologic features of 16 cases of surgically and pathologically proved juxtacortical chondrosarcoma were analyzed. The main radiograp-hic findings include: (1) A saucerlike or scalloped defect confined to the outer surface of cortex dut to tumor erosion; (2) Localized cortical proliferation and sclerosis; (3) Soft tissue mass and various forms of calcification within the tumor; but without a bony or calcified shell around the tumor mass and (4) sunray and/or laminated periosteal reaction. The origin of this tumor, its histopathology and classification were discussed. A preliminary investigation on the radiated periosteal reaction and its pathological basis was performed.

Functional evaluation using several evoked spinal cord potentials in elderly patients with cervical spondylotic myelopathy

BACKGROUND ： The recordings of evoked spinal cord potentials following epidural spinal cord stimulation are thought to be generated by volleys traversing the dorsal column pathway, and it may not directly reflect conduction defects in corticospinat tracts of cervical spinal cord. To our knowledge there has been few report using several evoked spinal cord potentials in function evaluation of the cervical spinal cord in eldedy patients with cervical spondylotic myelopathy （CSM）. OBJECTIVE： To investigate the function states of the cervical spinal cord in elderly patients with CSM and explore its pathophysictogic mechanism. DESIGN： Case observation SETTING ： Department of Orthopedics for the aged, Shenzhen Pingle Hospital of Orthopedics. Department of Orthopedic Surgery, Yamaguchi University School of Medicine. PARTICIPANTS ： A total of 23 eldedy patients with CSM who received treatment in the Department of Orthopedic Surgery, Yamaguchi University School of Medicine of Japan from January 2003 to February 2004 were enrolled in this study. Inclusive criteria： ① Multiple intervertebral levels of cervical spinal cord compression confirmed by MRI, e.g. 3 or more than 3 levels of compressin. ② Age ≥ 70 years old. ③ Numbness and sensory disturbance in the upper limbs and showed hyperreflexia in the lower limbs. Exclusive criteria： Patients with abnormal motor and sensory nerve conduction velocities in both upper and lower limbs were excluded. METHODS： Evoked spinal cord potentials （ESCPs） following transcranial electric stimulation （TCE-ESCPs）, epidural spinal cord stimulation （SpinaI-ESCPs） and median nerve stimulation （MN-ESCPs） were recorded in 23 patients from posterior epidural space intreoperatively. The abnormalities of TCE-ESCPs were defined as attenuation of amplitude of the D wave. The most cranial intervertebral level showing abnormal TCE-ESCPs with a marked reduction in size of the negative peak （reduction of over 50%） was considered as the upper level of the spinal cord lesion with respect to the corticospinal tract in white matter. The abnormalities of SpinaI-ESCPs were defined as marked reduction in the size of negative peak （reduction of over 50%）. The most caudal intervertebral level showing abnormal SpinaI-ESCPs was considered as the lower level of the spinal cord lesion with respect to the dorsal column pathway in white matter. The abnormalities of MN-ESCPs were defined as attenuation of the N13 amplitude,which was considered as the lesion level of the spinal cord with respect to the dorsal horn in gray matter. Radiological investigation： Lateral view of plain X-ray films was obtained in flexion and extension of the cervical spine. Instability of the cervical intervertebral level was determined as horizontal displacement of the vertebral body of over 3 mm. MAIN OUTCOME MEASURES ： The results of examination of TCE-ESCPs, SpinaI-ESCPs and MN-ESCPs in el- dedy patients with CSM. RESULTS： The 23 eldedy patients with CSM were participated in the result analysis. ①TCE-ESCPs： The impairment of the corticospinal tract in white matter at single intervertebral level was revealed in 18 of 23 patients by recordings of TCE-ESCPs （sensitivity 78%）. In the 18 patients, the lesion level was shown at the up- per cervical segment in 14 patients （C3-4n=10 and C4-5n=4）, and at the lower cervical segment in 4 patients （C5-6n=4）. ②Spinal-ESCPs： The impairment of the dorsal column pathway of white matter at single intervertebral level was revealed in 17 of 23 patients, by recordings of Spinal-ESCPs （sensitivity 74%）. In the 17 patients, the lesion level was presented at the upper cervical segment in 14 patients （C3-4n=10 and C4-5n=4）, and at the lower cervical segment in 3 patients （C5-6 n=3）. ③MN-ESCPs： All patients revealed abnormal MN-ESCPs at one or more intervertebral levels （sensitivity 100%）. The impairment at single intervertebral level was demonstrated in 17 patients, and the impairment at multiple intervertebral levels was shown in 4 patients （3 patients at the C3-4, C4-4, and C5-4~6, and one patient at the C4-5, C5-6, and C6-7）. ④Radiological findings： The Instability of the intervertebral level at the C3-4 or C4-5 motion segment was seen in 15 patients, with a total of 20 levels, and where 10 were at the C3-4 intervertebral level and 5 were at the C3-4, C4-5 intervertebral level. CONCLUSION ： The results suggest that in most elderly patients with CSM who have multiple intervertebral level compressions of the cervical spinal cord on MRI, white matter is impaired at the single cervical intervertebral level, and not only the dorsal column pathway, but also the corticospinal tract can be affected. Combined the findings of radiography, the excessive motion and instability of the C3-4 or C4-5 intervertebral level plays an important role in inducing the long tract lesion in elderly patients with CSM.

A Dielectric Ink Combining Acrylate and Cyanate Moieties for Inkjet 3D Printing with Good Thermal Stability

Inkjet 3D printing has potential in the additive manufacturing of electronic circuits and devices.However,inks that can be used for printing layers with T5%>300℃ or hardness>200 MPa have been rarely reported.Cyanate ester(CE)polymers have excellent thermal stability,high strength,and low shrinkage compared to other common dielectric inks for inkjet 3D printing,but cannot be quickly shaped by ultraviolet(UV)irradiation or thermal treatment.Combining CEs with UV-curable monomers may be a possible way to accelerate crosslinking,but there are challenges from the adverse effects of the dilution of both monomers.In this study,dielectric inks with acrylate and cyanate moieties were developed.The low viscosity and surface tension of the CE precursor(Bisphenol E cyanate ester)were combined with photocurable acrylate diluent monomers and cross-linker to realize an ink suitable for inkjet 3D printing.An internal dual three-dimensional cross-linked network structure resin was prepared by a combination of photocuring and thermal curing with T5%up to 326.69℃,hardness up to 431.84 MPa,dielectric constant of 2.70 at 8 GHz,and shrinkage of 1.64%.The developed dielectric inks can be applied to the 3D printing of printed circuit boards and other electronic devices that require dielectric properties.

Pedicle screw fixation against burst fracture of thoracolumbar vertebrae

Objective:To analyze the application of vertebral pedicle screw fixation in the treatment of burst fracture of thoracolumbar vertebrae. Methods:A total of 48 cases(31 males and 17 females,aged from 18-72 years,mean:41.3 years)with thoracolumbar vertebrae burst fracture were treated by pedicle screw system since January 2004.According to the AO classification of thoracolumbar vertebrae fracture, there are 36 cases of Type A,9 of Type B and 3 of Type C. Results:All patients were followed up for 6-25 months(average 12 months),no secondary nerve root injury,spinal cord injury,loosening or breakage of pedicle screw were observed.The nerve function of 29 patients with cauda equina nerve injury was restored to different degrees.The vertebral body height returned to normal level and posterior process angle was rectified after operation. Conclusions:The vertebral pedicle screw internal fixation was technologically applicable,which can efficiently reposition and stablize the bursting fractured vertabrae, indirectly decompress canalis spinalis,maintain spine stablity,scatter stress of screw system,reduce the risk of loosening or breakage of screw and loss of vertebral height, and prevent the formation of posterior convex after operation.

Cytotoxic Effect on Osteosarcoma MG-63 Cells by Degradation of Magnesium

Biocompatible and biodegradable magnesium （Mg） based metals have attracted great interest for use in orthopedic implants and devices. Based on our previous study that Mg with and without micro-arc oxidation （MAO） coating showed obvious cytotoxic effect on tumor cells due to the increase of pH value during the degradation of Mg, this study further evaluated the cytotoxic effect of Mg and MAO coated Mg on osteosarcoma （MG-63） cells by analyzing the cell adhesion, morphology and number through observation of scanning electron microscope, as well as live/dead staining, lactate dehydrogenase （LDH） activity and 4, 6- diamidino-2-phenylindole （DAPI） assay. The results indicated that, compared to titanium, Mg could strongly inhibit the cell adherence, morphology and number of MG-63 on the surface of the naked Mg, whereas the MAO coated Mg showed relative weak cytotoxic effect on MG-63 cells, expecting that magnesium based metals with suitable coating can be designed to be applied as tumor prosthesis in the clinical practice.

Promoting Bone Mesenchymal Stem Cells and Inhibiting Bacterial Adhesion of Acid-Etched Nanostructured Titanium by Ultraviolet Functionalization

Titanium(Ti) and its alloys are used extensively in orthopedic implants because of their excellent biocompatibility,mechanical properties and corrosion resistance. However,titanium-based implant materials face many severe complications,such as implant loosening due to poor osseointegration and bacterial infections,which may lead to implant failure. Hence,preparing a biomaterial surface,which enhances the interactions with host cells and inhibits bacterial adhesion,may be an optimal strategy to reduce the incidence of implant failure. This study aims to improve osseointegration and confer antibacterial properties on Ti through a combination of two surface modifications including nanostructuring generated by acid etching and ultraviolet(UV) light treatment.Our results showed that without UV treatment,the acid etching treatment of Ti surface was effective at both improving the adhesion of bone mesenchymal stem cells(BMSCs) and increasing bacterial adhesion. A further UV treatment of the acid-etched surface however,not only significantly improved the cell adhesion but also inhibited bacterial adhesion. The acid-etched nanostructured titanium with UV treatment also showed a significant enhancement on cell proliferation,alkaline phosphatase(ALP) activity and mineralization. These results suggest that such nanostructured materials with UV treatment can be expected to have a good potential in orthopedic applications.

Study on the Mechanism of Xiaotan Sanjie Recipe for Inhibiting Proliferation of Gastric Cancer Cells

Objective:To explore the mechanism of Xiaotan Sanjie Recipe (XtSjR, Recipe for dissolving phlegm to eliminate stagnation) in inhibiting proliferation of gastric cancer cells. Methods: The nude mouse human gastric cancer MKN-45 in situ transplantation tumor model was established by use of OB glue, and 40 model mice were randomized into 5 groups, model group, low-dose XtSjR group, middle-dose XtSjR group, high-dose XtSjR group, and 5-Fu group, 8 rats in each group. Human gastric cancer MKN-45 telomerase reverse transcriptase (hTERT) protein and mRNA expressions were assayed by immunohistochemical method and real-time fluorescence quantitative RT-PCR, and influences of XtSjR on the expressions of hTERT protein and mRNA were investigated in the nude mouse human gastric cancer MKN-45 in situ tumor transplantation model. Results: 1) There were significant differences in the mean tumor weight between the low-, middle-, high-dose XtSjR groups and the model group (all P<0.01); 2) There were significant differences in the hTERT positive expression rate between the middle-and high-dose XtSjR groups and the model group (P<0.05 or P<0.01); 3) There were significant differences in the hTERT mRNA content between the middle-and high-dose XtSjR groups and the model group (P<0.05 or P<0.01). Conclusion: 1) XtSjR has a marked inhibitory effect on the growth of gastric cancer cells; 2) XtSjR inhibits telomerase activity by down-regulating the expressions of hTERT protein and mRNA, shortening the length of cancer cell telomeres gradually, losing the ability to infinitely proliferate, and finally inhibiting the growth and proliferation of tumor cells.

Exclusive gene mapping of congenital microphthalmia in a Chinese family

Congenital microphthalmia is a developmental ocular disorder and might be caused by the mutations in the genes involved in eye development. To uncover the genetic cause in a six-generation Chinese pedigree with autosomal dominant congenital microphthalmia, we performed genescan and linkage analysis in this family. Fourteen microsatellite markers on chromosomes 3, 11, 14 and 15 were selected as genetic markers according to the five pre-viously reported loci associated with microphthalmia (MITF, SOX2, PAX6, MCOP and NNO2). The genomic DNA of each member in the pedigree was amplified with 14 pairs of fluorescence labeled primers. Genome screening and genotyping were conducted on ABI377 DNA sequencer and linkage analysis was performed with Linkage software package. All two-point LOD scores of linkage analysis between the suggested disease genes and microsatellite markers were <-2, which indicated that none of the five genes were responsible for microphthalmia in this Chinese family. Microphthalmia in this family may be caused by mutation in a new gene which is essential in eye development.