BACKGROUND:At present,there are many established femoral finite element studies,but previous studies focused on femoral biomechanics of the outside are few.OBJECTIVE:To establish three-dimensional finite element model of structure of the proximal femur,and to analyze its biomechanics in normal standing position to provide reasonable evidence for clinical application.DESIGN,TIME AND SETTING:A three-dimensional finite element model analysis was performed in General Hospital of Tianjin Medical University from December 2008 to April 2009.PARTICIPANTS:One male volunteer aged 30 years was enrolled at General Hospital of Tianjin Medical University.Femur lesion or injury was excluded by means of X-ray.METHODS:The primitive femur CT data were adopted according to Dicom 3.0 standard in Mimics so as to obtain the primitive three-dimensional femur model which was established via threshold defining,region enlarging and morphological performing.The primitive model was remeshed and combined with ANSYS software to create a final finite-element model.The model obtained by using the Mimics was loaded with 200 N vertical loading to check out the difference of the stress distribution.MAIN OUTCOME MEASURES:Using 200 N as the external load in the vertical direction,the Vonmises stress distribution of the femur was detected.RESULTS:The applications of Mimics and Ansys software could create a finite element model of proximal femur.It was found that the correspondent relationship between stress and structure in proximal femur was verified.CONCLUSION:Mimics can build more three-dimensional finite element models in line with the proximal femoral mechanical structure and mechanical properties.The mechanical properties of the femur are more credible,and the results of the analysis support the clinical application of the guidance.

ObjectiveTo measure the displacement parameters of the femoral head in space through CT three-dimensional reconstruction so as to re-understand impacted femoral neck fractures.MethodsFifty patients with impacted femoral neck fractures were included in the study.There were 17 males and 33 females.Bilateral proximal femurs of each patient were scanned by spiral CT preoperatively.Then these primitive CT data were reconstructed by Mimics 10.01 software.Registered the normal femur and fracture mirror model,the registered mirror model was generated a new mask in the CT cross-sectional images,marked key points in the masks and measured the displacement parameters of femoral head with three-dimensional measurement technology.ResultsIn the impacted femoral neck fractures,the femoral head displacement angle was 17.17°±10.40°,70％(35/50) of the patients had femoral head rotation angle was at 10° to 35°,and 30％(15/50) of the patients had femoral head space displacement more than 20°.The average displacement distance of femoral head center and the deepest point of fovea capitis were(6.49±3.60) mm and(10.42±5.92) mm,respectively.A high proportion of the impacted femoral neck fractures had a large of displacement in the three-dimensional space.It is not scientific to equal impacted femoral neck fractures to undisplaced fractures.ConclusionThree-dimensional reconstruction and digital measurement is a precise,efficient and convenient method for the measurement of femoral head displacement parameters in femoral neck fracture patients.The classic Garden classification for impacted femoral neck fractures has certain defects and limitations.Clinicians should re-understand impacted femoral neck fractures and choose more reasonable treatment.

Objective To prepare quality control samples for St.Louis encephalitis virus(SLEV)molecular detection by constructing pseudovirus containing target sequences of SLEV.Methods According to the principles of armored RNA technique, the prM gene sequence of SLEV was cloned into the prokaryotic expression vector to generate recombinant plasmid pSE380-MS2-SLEV.Then, recombinant E.coli transformed with the corresponding plasmid was induced with IPTG to produce recombinant pseudovirus particles.The particles were purified by chloroform and further characterized by double enzyme digestion and transmission electron microscopy.The temperature sensitivity experiments and quantitative RT-PCR were performed to validate the potential of these pseudovirus particles as quality control samples.Results PCR amplification and sequencing analysis confirmed that the prM gene sequence of SLEV was cloned into vector pSE380-MS2.Transmission electron microscopy showed that homogenous spherical particles with a diameter of about 25 nm were produced upon IPTG induction.The SLEV genomic RNA within the pseudovirus particles was resistant to DNaseⅠand RNase A digestion, and remained stable for 20 days at 37℃.These samples were validated with quantitative RT-PCR for SLEV.Conclusion The RNase-resistant and stable pseudovirus particles containing prM fragment of SLEV are constructed successfully, which can be used as positive quality control samples for RNA extraction and molecular detection.

Objective: To explore the efficacy of percutaneous vertebroplasty (PVP) in the treatment of osteoporotic vertebral compression fractures (OVCF). Methods: A retrospective analysis of 76 patients with OVCF treated with single and double pedicle approach PVP from April 2016 to June 2017 in the First Affiliated Hospital of He′nan University was conducted.According to the operation method, the patients were divided into unilateral group (42 patients, unilateral pedicle approach), and bilateral group (34 cases, bilateral pedicle approach). The operation time, number of intraoperative X-rays, amount of bone cement injection, height of the vertebral body and the complications were compared between the two groups.The visual analogue scale (VAS) and the Oswestry dysfunction index(ODI) score were used to assess the recovery of the patients. Results: The unilateral group had less operative time[(33.01±3.78)min], intraoperative X-ray number[(22.06±3.85) times]and bone cement injection[(3.53±0.42) mL] compared with the bilateral group (t=8.54, 5.98, 4.74, all P<0.05). There were no statistically significant differences in the recovery of vertebral height and complications between the two groups (all P>0.05). The postoperative VAS and ODI of the two groups were significantly improved compared with those before operation (all P<0.05). Conclusion In the case of reasonable indications, the unilateral approach PVP is better than bilateral, and unilateral approach PVP should be the first choice for OVCF.