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.

BACKGROUND:Searching for a porous three-dimensional (3D) scaffold holding good porosity, mechanical property and biocompatibility has become a hot spot, in which, 3D printing technology also plays apart. OBJECTIVE:To prepare silk fibroin/col agen scaffolds using 3D printing technology and detect its performance. METHODS:Silk fibroin/col agen scaffolds were constructed using 3D printing technology, and the silk fibroin/col agen mass ratio was 4:2 (group A) and 4:4 (group B), respectively. The porosity, water absorption expansion rate, mechanical properties and pore size of the composite scaffolds were detected. The passage 3 rat bone marrow mesenchymal stem cel s were seeded onto the two scaffolds. The cel proliferation was detected using MTT assay at 13 days of culture, and the cel morphology was observed by hematoxylin-eosin staining and scanning electron microscope at 14 days of culture. RESULTS AND CONCLUSION:The porosity, pore size, and water absorption expansion rate of group A were significantly larger than those of group B (P<0.05), while the elasticity modulus showed no significant difference between groups. Bone marrow mesenchymal stem cel s on the two scaffolds increased gradual y with time, especial y in the group A (P<0.05). Abundant cel s distributed evenly in the group A, while few cel s distributed unevenly in the group B. These results suggest that the 3D printed scaffolds composed by silk fibroin/col agen mass ratio of 4:2 holds good physicochemical performance and cytocompatibility.

In current study of femoral head necrosis and femoral neck fractures, more attentions has been paid to relationship between the femoral head trabecular bone within the spatial structure and its biomechanics. In this connection, PMMA (polymethyl methacrylate), special square iron, dental base acrylic resin liquid and powder were used to embed and fix human dry femur. Then, M618 Lie Axle Rectangle Desk Plane Grinding Machine was applied to grind the femur specimen, and then air blower clean, two-dimensional cross section image was obtained by using scanner. With Mimics software reconstruction, a three-dimensional model of spatial structure of trabecular bone was obtained, and the trabecular bone three-dimensional parameters were calculated. The authors obtained clear three-dimensional model of trabecular bone, reconstructed the real anatomic morphology of proximal femur. This is a good method to research into the interior structure of femur and to provide the foundation for the three-dimensional finite element analysis.
Biomechanical Phenomena ; Compressive Strength ; Computer Simulation ; Femur ; anatomy & histology ; diagnostic imaging ; physiology ; Finite Element Analysis ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; methods ; Models, Anatomic ; Radiography