In order to enhance the effect of comeal grafting, an assisting microsurgical robot has been developed. As one of principal issues for the robotic system design, type and size synthesis of the robotic mechanism is dis...In order to enhance the effect of comeal grafting, an assisting microsurgical robot has been developed. As one of principal issues for the robotic system design, type and size synthesis of the robotic mechanism is discussed. For this purpose, timeline subtask is analyzed with surgical component motion in manual comeal grafting microsurgery, as the reference of robotic mechanism synthesis. On the basis of study on the kinematic correlation between the arm structures and the wrist structures, configuration of joint is determined for the surgical task and motion in type synthesis of the mechanism. The objective for size synthesis of robotic mechanism is optimization of the mechanism dexterity as a manipulation capability. The condition number based on Jacob matrix is chosen as dexterity measure of the mechanism. The prototype is developed.展开更多
Objective： To study the alternation of distribution of the stress in the necrotic femoral head with different kinds of grafting materials by using three-dimensional element methods and find out the most optimal one w...Objective： To study the alternation of distribution of the stress in the necrotic femoral head with different kinds of grafting materials by using three-dimensional element methods and find out the most optimal one with sound biomechanical principles before clinical application. Methods： We prepared a three dimension finite element model of central femoral head necrosis with surface modeling technique （spiral ct）and calculated the peak stress index of necrotic portion in three situations：core drilling in 14 mm diameter and grafting with titanium, fibula, polylactide. Results： The peak stress index of normal femoral head was 0.05, but in osteonecrotic femoral head, the peak stress index was 13 times of the normal （0.67）. The value of necrotic portion with big shallow angle （0.67） was larger than the one with small deep angle （0.49）. Core drilling in 14 mm diameter and grafting with titanium, fibula and polyactide could diminish the bad stress in the necrotic portion respectirdy. The decrease volume in small necrotic area （90°） is marked（38% ）, while in big necrotic area （150°） it was indistinctive（ 10% ）. In the same necrotic portion,the decrease volume with titanium was（38% ） larger than with the fibula （37%）, and also larger than with the polyactide（29% ）. Conclusion： In necrotic portion of femoral head, the badshess could produce 13 times of the normal one. Grafting with titanium, fibula and polyactide could reduce the bad stress respectively. The effect of titanium is most marked, second is fibula and polyactide is indistinctive. The effect was in big necrotic portion is bad, the best effect was in small necrotic portion.展开更多
基金This project is supported by National Hi-tech Research and DevelopmentProgram of China (863 Program, No.2002AA420110).
文摘In order to enhance the effect of comeal grafting, an assisting microsurgical robot has been developed. As one of principal issues for the robotic system design, type and size synthesis of the robotic mechanism is discussed. For this purpose, timeline subtask is analyzed with surgical component motion in manual comeal grafting microsurgery, as the reference of robotic mechanism synthesis. On the basis of study on the kinematic correlation between the arm structures and the wrist structures, configuration of joint is determined for the surgical task and motion in type synthesis of the mechanism. The objective for size synthesis of robotic mechanism is optimization of the mechanism dexterity as a manipulation capability. The condition number based on Jacob matrix is chosen as dexterity measure of the mechanism. The prototype is developed.
文摘Objective： To study the alternation of distribution of the stress in the necrotic femoral head with different kinds of grafting materials by using three-dimensional element methods and find out the most optimal one with sound biomechanical principles before clinical application. Methods： We prepared a three dimension finite element model of central femoral head necrosis with surface modeling technique （spiral ct）and calculated the peak stress index of necrotic portion in three situations：core drilling in 14 mm diameter and grafting with titanium, fibula, polylactide. Results： The peak stress index of normal femoral head was 0.05, but in osteonecrotic femoral head, the peak stress index was 13 times of the normal （0.67）. The value of necrotic portion with big shallow angle （0.67） was larger than the one with small deep angle （0.49）. Core drilling in 14 mm diameter and grafting with titanium, fibula and polyactide could diminish the bad stress in the necrotic portion respectirdy. The decrease volume in small necrotic area （90°） is marked（38% ）, while in big necrotic area （150°） it was indistinctive（ 10% ）. In the same necrotic portion,the decrease volume with titanium was（38% ） larger than with the fibula （37%）, and also larger than with the polyactide（29% ）. Conclusion： In necrotic portion of femoral head, the badshess could produce 13 times of the normal one. Grafting with titanium, fibula and polyactide could reduce the bad stress respectively. The effect of titanium is most marked, second is fibula and polyactide is indistinctive. The effect was in big necrotic portion is bad, the best effect was in small necrotic portion.
