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Objective To study mechanical properties of porous scaffolds with lattice Weaire-Phelan (LWP) structure and precisely simulate the whole process of compression test using finite element method. Methods The Ti6Al4V (TC4) porous scaffolds with different porosities were manufactured by selective laser melting (SLM) technology, and their mechanical properties were measured by uniaxial compressive tests, and compared with those of human bones and porous scaffolds with other cellular structures. Four types of material models were verified for their effects on the simulation of porous scaffold compression. Results LWP samples presented the elastic modulus close to that of human cancellous bone and significantly higher yield strength than that of cortical bone in most parts of human body. Compared with other scaffold structures, LWP samples exhibited the lowest elastic modulus and highest yield strength. The simulated results derived from the proposed material model in this study, namely, Johnson-Cook constitutive model and failure model based on dynamic geometric strain (JCDG), were proved very consistent with the experimental data. Conclusions LWP scaffolds as the bone repair biomaterials exhibite more excellent mechanical properties than the scaffolds with other structures. JCDG is more beneficial for establishing the reasonable simulation model of porous scaffolds compression, compared with other reported material models.
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Objective To explore the application scope of small splint in the treatment of type-C distal radius fractures. Methods According to CT scan data from the right forearm of a healthy male volunteer, the three-dimensional model of normal distal radius was established. According to AO classification, the fracture line based on normal model was divided to establish nine kinds of high-order tetrahedral mesh models of the upper forearm with C-type fracture. Finite element analysis on nine kinds of fracture models was conducted in ANSYS 15.0 software to obtain the corresponding stress values, and then the stress distribution contours were generated. Results As soft tissues of the wrist were thin with more fracture blocks, after the splint was fixed, the stress on the wrist under 100 N maximum physiological axial load was significantly larger compared with that on the other parts, and the compressive stress was mainly concentrated on the wrist joint. The fixed effect of C2.2, C2.3, C3.2, C3.3-type fracture by small splint was relatively poor, as such comminuted fracture would cause too many and too small fracture blocks, while the fixed effect of C1.1, C1.2, C1.3, C2.1 and C3.1-type fracture was better. Conclusions Through the related finite element study on the treatment of C-type fracture distal radius with small splint, the application scope of small splint was preliminarily determined, which could provide some reference for clinical work.
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Objective To quantitatively study the pressure of residual lateral displacement in distal radius AO C3.1 fracture after manual reduction corrected by dynamic airbag pad using finite element analysis and to verify its effectiveness for correcting the residual displacement of fractures. Methods Imageware 13.0, Mimics 15.0 and ANSYS Workbench were used to simulate 1 cm residual lateral displacement after manual reduction of distal radius fracture corrected by dynamic airbag pad. Then the correlation between the distance of residual lateral displacement and the adjustment of dynamic airbag pad pressure were quantitatively analyzed. Results In the case of constant load restrained by airbag ribbon, during the process of pressure adjustment by splint pad, the stress was mainly distributed in the fracture end where the airbag pad was located. About 2.4 kPa pressure was needed to correct 1 mm displacement on radial side, while about 1.3 kPa pressure was needed to correct 1 mm displacement on dorsal side. The dynamic airbag pad was depressurized after the restoration of residual shift. At this time, displacement could be effectively prevented due to the constant load of airbag ribbon and the frictional load at the fracture end. Conclusions In the case of constant load constrained by airbag ribbon, intelligent airbag splint can effectively correct the residual lateral displacement after the manual reduction of the distal radius AO C3.1 fracture and prevent it from being displaced by adjusting pressure of the dynamic airbag pad.
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OBJECTIVE:To systematically review the efficacy and safety of reinforcing kidney and invigorating spleen princi-ple in the treatment of primary osteoporosis (POP) in middle and elderly aged patients,and provide evidence-based reference for clinic. METHODS:Retrieved from VIP,Wanfang Database,CJFD,Medline,PubMed,Elsevier,Springer,Web of Science and Ovid,randomized control trials (RCT) about reinforcing kidney and invigorating spleen principle (test group) versus other meth-ods(no reinforcing kidney and invigorating spleen principle,control group)in the treatment of POP were collected. Meta-analysis was performed by using Rev Man 5.3 software provided by Cochrane after data extraction and quality evaluation modified by Jadad scale. RESULTS:Totally 28 RCTs were enrolled,involving 2849 patients. Results of Meta-analysis showed,the total effective rate [OR=3.80,95%CI(2.76,5.23),P<0.001],BGP level [MD=2.23,95%CI(1.80,2.66),P<0.001],BMD level of femoral neck [MD=0.04,95%CI(0.00,0.08),P=0.05] and BMD level of lumbar spine [MD=0.07,95%CI(0.03,0.11),P=0.001] in test group were significantly higher than control group,ALP level [MD=-5.59,95%CI(-10.51,-0.66),P=0.03] and VAS score [MD=-1.38,95%CI(-1.87,-0.89),P<0.001] were significantly lower than control group,with statistical significance. There were no significant differences in U-Ca/Cr [MD=-0.07,95%CI(-0.17,0.02),P=0.12] and serum Ca2+ level [MD=0.16,95%CI (-0.07,0.39),P=0.17] in 2 groups. CONCLUSIONS:Reinforcing kidney and invigorating spleen principle can improve patients' osteogenesis during bone metabolism,reduce the activity of the osteoclastic process and relief patients'pain in the treatment of POP.