ABSTRACT
Objective To design a notched flexible articulation applied to electric stapler and study its turning performance. Methods The notched flexible articulation was designed and modeled. The kinematics and statics models of the articulation were established for simulation calculations. The stress, deflection angle, top displacement and driving force of the articulation with 3 different turning structures were studied under equal and variable stiffness of symmetrical notches by using finite element simulation. An experimental platform for performance test of the turning structure was built to verify the simulation results and the model. Results The theoretical model of the turning structure in bending process was basically consistent with the experimental results. With the optimization of symmetrical notch stiffness, the maximum stress of the articulation with variable stiffness was reduced by 20.64% and 39.20%, respectively. The articulation with variable stiffness required the smallest tensile force during bending, which was 33.41% lower than that of the articulation with equal stiffness, and the tip displacement (30.8 mm) along the bending plane was the smallest. The maximum deflection angle for the articulation with 3 different turning structures all could reach 90°. Conclusions The kinematics and statics models of the articulation can be used for the calculation of its tensile force and position changes. The turning performance of the articulation with variable stiffness using symmetrical notch is better than that with equal stiffness. The notched flexible articulation meets the design requirements and the turning needs of electric stapler.
ABSTRACT
Objective To develop a new type of electric stapler, so as to solve the problems of insufficient rotation angle, inconvenient operation and difficulty in controlling the pressing strength of existing products. Methods An electric stapler was designed and manufactured. The motion trajectory curve of the prototype was measured by using the three-coordinate imaging instrument to build functional test platform of the prototype, and the goodness of fit was used to evaluate consistency between the theoretical curve and the measured curve. The small intestine tissues of fresh pig were anastomosed at different bending angles of the front end, and the forming rate of the anastomotic stoma was measured. Results The goodness of fit between the test curve and the theoretical curve for both turning motion and shooting motion was ideal, while the goodness of fit between the test curve and the theoretical curve for pressing motion was not ideal when the turning joint was bent at 0°-30°, and was ideal when it was bent at 45°-60°. In performance test, the deformity rate of the nail was smaller than 1.14%, indicating that the bending angle had no significant impacts on the anastomotic effect. Conclusions The kinematics curves of shooting motion and turning motion are consistent with the theoretical curves. The pressing motion curves fluctuate at different bending angles, which will not affect the anastomotic effect, and the effect of the electric stapler meets the clinical requirements.
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Objective To develop a novel electric stapler, so as to improve the automation, convenience and precision of minimally invasive surgery. Methods The clamping, firing and turning mechanism of the new electric stapler was innovatively designed to realize the electric drive of minimally invasive surgical anastomosis on the basis of traditional mechanical stapler. The motion process of electric clamping, firing and double-screw turning mechanism was analyzed in detail, and the equations for motion function of three mechanisms were solved, providing a theoretical basis for the intelligent control algorithm of electric stapler. Results The electric clamping and firing process was simulated using ADAMS software to verify the equation of motion. The prototype of the new electric stapler was made, and the anastomosis experiment and blasting pressure experiment of the in vitro small intestine tissues were carried out. The range of anastomotic blasting pressure was between 3.7 kPa and 11.67 kPa, meeting the basic requirements in clinic. Conclusions The structure of the new electric stapler can meet the requirements of electric pressing and firing in minimally invasive surgery, contributing to achieve tissue anastomosis more conveniently, quickly and effectively.
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Objective To investigate the related factors of postoperative hypocalcemia after thyroid carc-er surgery.Methods 346 cases of thyroid carcer patients undergoing surgery from Jan .2013 to Dec.2013 in the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed .Results 129 cases developed hepocalcemia after thyroid surgery .Among the related factors that may cause postoperative hypocalcemia , the scope of surgery , parathyroid injury and secondary surgery might play important roles .Conclusions The inci-dence of postoperative hypocalcaemia is high after total thyroidectomy .Patients with reoperation and lymph node dissection have an increased rate of postoperative hypocalcaemia .In order to reduce hypocalcaemia incidence ,sur-gons need to protect parathyroid blood supply in thyroid surgery and give calcium after surgery .
ABSTRACT
Objective To evaluate the curative effects of carbon nanoparticles on central lymphnode dis -section in papillary thyroid carcinoma ( PTC) .Methods 72 PTC patients were randomly divided into two groups:carbon nanoparticle group(n=32)and the control group(n=32).Patients in the carbon nanoparticle group were injected with carbon nanoparticles during surgery .Patients in the control group had conventional surgery .The number of lymph nodes being dissected ,lymph node metastasis , and the rate of hypoparathyroidism were compared between the two groups .Results The number of lymph nodes dissected in nanoparticle group ( n =312 ) was much bigger than that in the control group (n=189)(P0.01;χ2 =1.048).Conclu-sions The lymphatic tracer technique may improve the number of lymph nodes dissected in central region of PTC and reduce parathyroid gland damage .