With the gradual deepening of study on the parallel mechanism,the difficulty brought by the existence of coupling to the theoretical analysis and practical application of parallel mechanisms is becoming increasingly a...With the gradual deepening of study on the parallel mechanism,the difficulty brought by the existence of coupling to the theoretical analysis and practical application of parallel mechanisms is becoming increasingly apparent.The research on the decoupled parallel mechanism is currently one of the hot fields.Though most of the rotational parallel mechanisms,which has been widely used in spatial orientation fields,are not decoupled.It is comparative difficult for the synthesis of fully decoupled rotational parallel mechanisms,and the number of the existing parallel mechanisms which can realize rotational decoupling is limited.In addition,most of the existing rotational decoupled parallel mechanism are obtained depending on the experience of the researcher,and don't possess the general theoretical significance.Based on the screw theory,this paper presents the rotational conditions of the parallel mechanism through the analysis of the relationship between the degree of freedom of the parallel mechanism and its limbs.The synthesis rule of the limbs for decoupled rotational parallel mechanism is established according to the twist screw system of the limbs,which assures the decoupling of the rotations in each limb.The selection principle of the input pairs for the rotation driven limbs is proposed,then the type synthesis method for rotational decoupled parallel mechanisms is formed.With this type synthesis method,synthesis of the rotational decoupled parallel mechanisms is performed,which can provide a reference for the development of the novel type parallel mechanisms with independent intellectual property rights.展开更多
This study aimed to introduce a novel mini-open pedicle screw fixation technique via Wiltse approach, and com- pared it with the traditional posterior open method. A total of 72 cases of single-segment thoracolumbar f...This study aimed to introduce a novel mini-open pedicle screw fixation technique via Wiltse approach, and com- pared it with the traditional posterior open method. A total of 72 cases of single-segment thoracolumbar fractures without neurologic injury underwent pedicle screw fixation via two different approaches. Among them, 37 patients were treated using posterior open surgery, and 35 patients received mini-open operation via Wiltse approach. Crew placement accuracy rate, operative time, blood loss, postoperative drainage, postoperative hospitalization time, radiation exposure time, postoperative improvement in R value, Cobb＇s angle and visual analog scale （VAS） scores of the two methods were compared. There were no significant differences in the accuracy rate of pedicle screw placement, radiation exposure and postoperative R value and Cobb＇s angle improvement between the two groups. However, the mini-open method had obvious advantages over the conventional open method in operative time, blood loss, postoperative drainage, postoperative hospitalization time, and postoperative improvement in VAS. The mini-open pedicle screw technique could be applied in treatment of single-segment thoracolumbar fracture without neurologic injury and had advantages of less tissue trauma, short operative and rehabilitative time on the premise of guaranteed accuracy rate and no increased radiation exposure.展开更多
Background： Sacroiliac （SI） screw fixation is a demanding technique, with a high rate of screw malposition due to the complex pelvic anatomy. TiRobot- is an orthopedic surgery robot which can be used for SI screw f...Background： Sacroiliac （SI） screw fixation is a demanding technique, with a high rate of screw malposition due to the complex pelvic anatomy. TiRobot- is an orthopedic surgery robot which can be used for SI screw fixation. This study aimed to evaluate the accuracy of robot-assisted placement of SI screws compared with a freehand technique. Methods：Thirty patients requiring posterior pelvic ring stabilization were randomized to receive freehand or robot-assisted SI screw fixation, between January 2016 and June 2016 at Beijing Jishuitan Hospital. Forty-five screws were placed at levels S1 and S2. In both methods, the primary end point screw position was assessed and classified using postoperative computed tomography. Fisher＇s exact probability test was used to analyze the screws＇positions. Secondary end points, such as duration of trajectory planning, surgical time after reduction of the pelvis, insertion time for guide wire, number of guide wire attempts, and radiation exposure without pelvic reduction, were also assessed. Results： Twenty-three screws were placed in the robot-assisted group and 22 screws in the freehand group; no postoperative complications or revisions were reported. The excellent and good rate of screw placement was 100% in the robot-assisted group and 95% in the freehand group. The P value （0.009） showed the same superiority in screw distribution. The fluoroscopy time after pelvic reduction in the robot-assisted group was significantly shorter than that in the freehand group （median [Q1, Q3]： 6.0 [6.0, 9.0] s vs. median [Q1, Q3]： 36.0 [21.5, 48.0] s; χ2 = 13.590, respectively, P 〈 0.001）; no difference in operation time after reduction of the pelvis was noted （χ2 = 1.990, P = 0.158）. Time for guide wire insertion was significantly shorter for the robot-assisted group than that for the freehand group （median [Q1, Q3]： 2.0 [2.0, 2.7] min vs. median [Q1, Q3]： 19.0 [15.5, 45.0] min; χ2 = 20.952, respectively, P 〈 0.001）. The number of guide wire attempts展开更多
Pedicle screw placement is an advanced posterior fixation technique that can provide patients with great biomechanical benefits. However, the morphology of the vertebrae is complex and it is very difficult to insert s...Pedicle screw placement is an advanced posterior fixation technique that can provide patients with great biomechanical benefits. However, the morphology of the vertebrae is complex and it is very difficult to insert screws without penetrating the cortex. Thus, new techniques for improving the accuracy of pedicle screw placement and safety are required. Herein,展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 50875227, 51005195)
文摘With the gradual deepening of study on the parallel mechanism,the difficulty brought by the existence of coupling to the theoretical analysis and practical application of parallel mechanisms is becoming increasingly apparent.The research on the decoupled parallel mechanism is currently one of the hot fields.Though most of the rotational parallel mechanisms,which has been widely used in spatial orientation fields,are not decoupled.It is comparative difficult for the synthesis of fully decoupled rotational parallel mechanisms,and the number of the existing parallel mechanisms which can realize rotational decoupling is limited.In addition,most of the existing rotational decoupled parallel mechanism are obtained depending on the experience of the researcher,and don't possess the general theoretical significance.Based on the screw theory,this paper presents the rotational conditions of the parallel mechanism through the analysis of the relationship between the degree of freedom of the parallel mechanism and its limbs.The synthesis rule of the limbs for decoupled rotational parallel mechanism is established according to the twist screw system of the limbs,which assures the decoupling of the rotations in each limb.The selection principle of the input pairs for the rotation driven limbs is proposed,then the type synthesis method for rotational decoupled parallel mechanisms is formed.With this type synthesis method,synthesis of the rotational decoupled parallel mechanisms is performed,which can provide a reference for the development of the novel type parallel mechanisms with independent intellectual property rights.
基金supported by the National Natural Science Foundation of China(Grant No.30973058, 81171694,and 81371968)the Program for Development of Innovative Research Team in the First Affiliated Hospital of NJMU(No.IRT-015)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This study aimed to introduce a novel mini-open pedicle screw fixation technique via Wiltse approach, and com- pared it with the traditional posterior open method. A total of 72 cases of single-segment thoracolumbar fractures without neurologic injury underwent pedicle screw fixation via two different approaches. Among them, 37 patients were treated using posterior open surgery, and 35 patients received mini-open operation via Wiltse approach. Crew placement accuracy rate, operative time, blood loss, postoperative drainage, postoperative hospitalization time, radiation exposure time, postoperative improvement in R value, Cobb＇s angle and visual analog scale （VAS） scores of the two methods were compared. There were no significant differences in the accuracy rate of pedicle screw placement, radiation exposure and postoperative R value and Cobb＇s angle improvement between the two groups. However, the mini-open method had obvious advantages over the conventional open method in operative time, blood loss, postoperative drainage, postoperative hospitalization time, and postoperative improvement in VAS. The mini-open pedicle screw technique could be applied in treatment of single-segment thoracolumbar fracture without neurologic injury and had advantages of less tissue trauma, short operative and rehabilitative time on the premise of guaranteed accuracy rate and no increased radiation exposure.
文摘Background： Sacroiliac （SI） screw fixation is a demanding technique, with a high rate of screw malposition due to the complex pelvic anatomy. TiRobot- is an orthopedic surgery robot which can be used for SI screw fixation. This study aimed to evaluate the accuracy of robot-assisted placement of SI screws compared with a freehand technique. Methods：Thirty patients requiring posterior pelvic ring stabilization were randomized to receive freehand or robot-assisted SI screw fixation, between January 2016 and June 2016 at Beijing Jishuitan Hospital. Forty-five screws were placed at levels S1 and S2. In both methods, the primary end point screw position was assessed and classified using postoperative computed tomography. Fisher＇s exact probability test was used to analyze the screws＇positions. Secondary end points, such as duration of trajectory planning, surgical time after reduction of the pelvis, insertion time for guide wire, number of guide wire attempts, and radiation exposure without pelvic reduction, were also assessed. Results： Twenty-three screws were placed in the robot-assisted group and 22 screws in the freehand group; no postoperative complications or revisions were reported. The excellent and good rate of screw placement was 100% in the robot-assisted group and 95% in the freehand group. The P value （0.009） showed the same superiority in screw distribution. The fluoroscopy time after pelvic reduction in the robot-assisted group was significantly shorter than that in the freehand group （median [Q1, Q3]： 6.0 [6.0, 9.0] s vs. median [Q1, Q3]： 36.0 [21.5, 48.0] s; χ2 = 13.590, respectively, P 〈 0.001）; no difference in operation time after reduction of the pelvis was noted （χ2 = 1.990, P = 0.158）. Time for guide wire insertion was significantly shorter for the robot-assisted group than that for the freehand group （median [Q1, Q3]： 2.0 [2.0, 2.7] min vs. median [Q1, Q3]： 19.0 [15.5, 45.0] min; χ2 = 20.952, respectively, P 〈 0.001）. The number of guide wire attempts
文摘Pedicle screw placement is an advanced posterior fixation technique that can provide patients with great biomechanical benefits. However, the morphology of the vertebrae is complex and it is very difficult to insert screws without penetrating the cortex. Thus, new techniques for improving the accuracy of pedicle screw placement and safety are required. Herein,
