ABSTRACT
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 investigate the value of modified pancreatoduodenectomy in the treatment of ampullary carcinoma by comparing the efficacy of pancreatoduodenectomy with preservation of ascending portion of duodenum and that of Whipple procedure. Methods The clinical data of 133 patients with ampullary carcinoma who had been admitted to the Qilu Hospital from 1990 to 2006 were retrospectively analyzed. Of the 133 patients, 88 received Whipple procedure (group A) and 45 received pancreatoduedenectomy with preservation of ascending portion of duodenum (group B). The preoperative condition of the patients and short- and long-term efficacy of the 2 procedures were compared by Fisher exact probability, t test, chi-square test, Kaplan-Meier survival curve and Log-rank test, and the differences between the efficacy of the 2 procedures were compared. Results The operation time, time of gastrointestinal function recovery, hospital stay and ratio of patients with blood transfusion were (366±111) minutes, (7.4±1.4) days, (24±9) days and 76% (67/88) in group A, and (325±32)minutes, (4.3±1.4)days, (31±14)days, 42% (19/45) in group B, with significant difference between the 2 groups (t = 2.34, 2.08, 1.98 ; χ2 = 14.99, P < 0.05). The medium survival time of patients in groups A and B were (19.0±1.5)months and (16.9±1.7) months, with no significant difference between the 2 groups (χ2 = 0.46, P > 0.05). There was no significant difference in the occurrence of postoperative complications between the 2 groups (P > 0.05). Conclusions Pancreateduodenectomy with preservation of ascending portion of duodenum can be applied for patients with ampullary carcinoma.
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Objective To evaluate the effect of surgical management of primary venous reflux disease in lower extremity. Methods Literatures about the surgical management of venous reflux disease in lower extremity were collected and reviewed. Results In patients with primary venous reflux disease,comprehensive surgical management of concomitant superficial,deep and perforating veins might greatly improve the clinical effect.Conclusion Comprehensive surgical management will be the direction of surgical management of primary venous reflux disease in lower extremity.