IROS2019国际学术会议论文集 0964

Abstract 3D printing in medical technology is mainly used to produce customized devices for surgical planning or surgical guides and templates However for laparoscopic systems 3D printing is hardly used A challenge is the transmission of the necessary forces required in laparoscopic surgery We designed and manufactured a 3D printed customizable manipulator system for Single Incision Laparoscopic Surgery SILS fulfilling the force related requirements in laparoscopic surgery The Single Incision Laparoscopic Manipulator System can apply forces at its tip up to 5 6 N with acceptable operating forces not exceeding 30 N We showed the functionality of the manipulator system in a manipulation experiment in comparison to standard SILS instruments I INTRODUCTION Single incision laparoscopic surgery SILS also known as laparoendoscopic single site surgery LESS or single port surgery follows the current trend of reducing the invasiveness of surgical interventions In comparison to standard laparoscopic surgery it has comparable short term outcomes and provides advantages to patients such as less blood loss shorter hospital stays and higher overall satisfaction levels due to a better cosmetic outcome 1 In contrast SILS procedures are more challenging for surgeons Because there is only one skin incision the operation of standard instruments usually specially prebent instruments is more difficult The main challenges of this is the lack of triangulation and the collision and obstruction of the instruments against each other 2 3 Therefore there is a demand for suitable instruments manipulators and robotic systems for SILS 3 Today the da Vinci System Intuitive Surgical Inc Sunnyvale CA USA is the most widely used robotic system for laparoscopic surgery An overview of the developments and patents in robotic surgery is given in 4 5 For robotic surgery in SILS the da Vinci Xi single port SP 1098 platform has FDA approval 6 This master slave system includes a flexible telescope with 3D binocular view and three instruments 7 The SPORT Surgical System Titan Medical Inc Toronto Canada is also a robotic master slave system for SILS with two instruments and 3D visualization on a monitor 8 The developing company intends to receive an Investigational Device Exemption IDE from the FDA in 2019 9 Regarding manipulators for SILS there is the SPIDER surgical system TransEnterix Morrisville NC USA which the FDA approved in 2009 5 It is a purely mechanical manipulator with two manipulator arms and two working channels for a laparoscope and an additional instrument 10 It was further developed to the robotic SILS version SurgiBot but the FDA approval was denied in 2016 5 SymphonX in the developing phase called FMX314 Surgical Platform Fortimedix Surgical B V Nuth The Netherlands is also a purely mechanical system with two bendable instruments and two additional channels which fits into a 15 mm trocar 11 and which has the FDA approval due to its substantial equivalence to the SPIDER surgical system 12 Currently these systems for SILS are manufactured using conventional manufacturing methods 3D printing allows the manufacturing of highly complex structures the integration of several parts and functional elements into one part to reduce the manufacturing and assembly time and cost efficient series production with small quantities 13 Additionally we assume that there may be a benefit for customized systems that are adapted to the medical application and indication the patient the instruments and the user 14 Currently 3D printing is mainly utilized as a manufacturing process for the production of customized devices e g anatomic models for surgical planning or surgical guides and templates 15 16 3D printing of surgical instruments is used for product optimizing during the design process 17 18 and may be used for on demand manufacturing where standard surgical devices are not available 19 20 For laparoscopic systems 3D printing is rarely used e g there is a 3D printed steerable instrument prototype DragonFlex 21 The design and 3D printing of individualized surgical systems is our long term goal 14 The concept is based on a modular and flexible manipulator system structure design that can be semi automatically adapted and manufactured using rapid manufacturing techniques for use with standard instruments The endoscopic version of the manipulator systems was successfully tested in a randomized study in a porcine model 22 The applicability of 3D printing as a manufacturing process for laparoscopic instruments is uncertain as large forces act on the 3D printed instruments during laparoscopic surgery A simple massive 3D printed retractor for open surgery was capable of holding 13 6 kg before breaking and 3D Printed Single Incision Laparoscopic Manipulator System Adapted to the Required Forces in Laparoscopic Surgery Sandra V Brecht Matthias Stock Jens Uwe Stolzenburg and Tim C Lueth Member IEEE The authors would like to thank the Deutsche Forschungsgemeinschaft DFG for supporting the project LU 604 27 2 Sandra V Brecht Matthias Stock and Tim C Lueth are with the Department of Mechanical Engineering Institute of Micro Technology and Medical Device Technology MiMed of the Technical University of Munich Munich Germany corresponding author phone 49 89 289 15189 fax 49 89 289 15192 e mail sandra brecht tum de Jens Uwe Stolzenburg is with the Department of Urology of the Universit tsklinikum Leipzig A R University of Leipzig Leipzig Germany 2019 IEEE RSJ International Conference on Intelligent Robots and Systems IROS Macau China November 4 8 2019 978 1 7281 4003 2 19 31 00 2019 IEEE6296 therefore fulfilled the force requirements 20 Our first fabrication of a functional model of a 3D printed laparoscopic manipulator was not yet designed for the forces applied in laparoscopic surgery Therefore we could only apply forces up to 0 6 N 23 In summary there is no 3D printed SILS system available that is capable of managing the forces required in laparoscopic surgery In this paper we demonstrate our 3D printed Single Incision Laparoscopic Manipulator System for SILS that can apply the forces required in laparoscopic surgery II MATERIALS AND METHODS The system should be able to apply forces of approximately 3 N at the instrument s tip 24 26 To consider the surgeon s physical workload the acceptable operating forces for all operating directions are calculated according to the force atlas of Wakula et al 2009 which can be used for all workplaces where exercises of strength regularly occur in the postures examined 27 see also 28 The actual measured operating forces have to be smaller than the acceptable operating forces which correspond to the reduced recommended forces limits to minimize the risk of overload see Eq 1 27 p 193 28 The recommended force limits are calculated in Eq 2 with the values of Table 1 27 p 194 28 0 85 1 1 2 1 2 3 2 TABLE 1 VALUES FOR THE CALCULATION OF THE ACCEPTABLE OPERATING FORCES FOR ALL OPERATING DIRECTIONS FOR OPERATING THE CONTROL UNITS Body posture and operating directions for operating the control units A A B B C C 515 N 530 N 340 N 380 N 315 N 280 N 1 0 0 5 0 5 0 65 0 65 0 65 0 65 0 5 0 4 0 6 0 9 0 6 0 5 0 5 1 0 1 0 1 0 1 0 1 0 1 0 52 N 80 N 99 N 74 N 51 N 46 N 44 N 68 N 85 N 63 N 44 N 39 N Legend Maximal static action force with force percentile P50 for existing analysis 27 p 195 1 Influence of age not used for existing analysis 27 p 189 2 Influence of gender 0 5 for force direction and 0 65 for force direction and for female and male 28 1 Frequency for force exertions 1 after Schultetus 29 p 21 55 one sided for one handed exertion of strength assumption frequency of the movements of the control unit per minute 12 27 p 183 2 Biomechanics Factor upright symmetrical posture one handed operation of the control unit 27 p 184 3 Physiology Factor upright symmetrical posture one handed operation of the control unit 27 p 185 recommended operation force limit for operating the control units acceptable operating force for operating the control units Additionally the system should enable the manipulation of tissue with a minimum of two instruments and allow triangulation of the instruments via one minimally invasive skin incision without collision or mutual obstruction of the instruments It should be possible to change between different instrument types and to move the tip of the instruments radially and axially and to rotate it 360 in both directions to adjust the grip angle For visualization and illumination a rigid telescope should be used Further requirements are defined in 23 30 We implemented a Single Incision Laparoscopic Manipulator System that consists of an overtube structure with a rigid shaft with flexible manipulator arms and control units and provides 7 degrees of freedom Fig 1 A rigid telescope and flexible laparoscopic instruments can be inserted into the overtube structure Furthermore there is a channel for an additional instrument for suction and irrigation or material transport Figure 1 Single Incision Laparoscopic Manipulator System with two mechanical control units 1 for controlling two laparoscopic instruments 2 which are guided through a rigid shaft 3 and two manipulator arms 4 The functionality of the Single Incision Laparoscopic Manipulator System is actually purely mechanical but the integration into a robotic system is a possibility because the manipulator system is modular and the interfaces for control could also be connected to an electrical control unit We also proposed a concept for a laparoscopic manipulator system with three arms for manipulation and guiding of an ultrasound probe to extend the system with augmented reality features 30 The manipulator arms can be controlled via the mechanical control units for opening and bending the arms in all directions in out up down Fig 2 The flexible laparoscopic instruments can be moved axially The effectors of the flexible laparoscopic instruments can be opened and closed and rotated 360 in both directions by the instruments handle The control units can be fixed in any position on the operating table rail to avoid problems with position change when the operating table is moved Additionally the height and angle of the control units in relation to the fixation at the operating table can be adjusted to adapt to the surgeon s body dimensions The manipulator is inserted through an access system with several access ports for further instruments One of these ports can also be used at the beginning of the operation 6297 for monitoring the insertion of the manipulator system with the laparoscope To prevent the collision and obstruction of the instruments against each other the movable manipulator arms are completely inside the body and the telescope in the middle is inaccessible for the instruments For approximate positioning of the manipulator arms and the laparoscope the shaft of the manipulator can be moved axially and tilted around the entry port The shaft can either be fixed with a supporting arm or guided by an assistant later on The Single Incision Laparoscopic Manipulator System was developed on the basis of the previous work on endoscopic manipulators 23 30 using the principle of methodical construction and Failure Mode and Effects and Criticality Analysis to ensure the safety of the system The manipulator system is based on a semi automatically adaptable CAD drawing and therefore allows a customization The length of the shaft plus the manipulator arms can be adapted to the length needed from the entry point to the operation field Similarly the diameter of the channels for the instruments the laparoscope the additional instruments and the associated outer diameter of the shaft can be adapted to the preferred set of instruments We use the following diameters for our set of instruments 5 6 mm for the instrument channels 5 2 mm for the laparoscope channel 5 6 mm for the additional instrument channel 22 mm for the outer diameter The length of the whole instrument channel is 750 mm which includes 160 mm for the manipulator arms The monolithic designed manipulator arms are divided into three segments the first segment for opening the arms the second segment for moving the arms up and down and the third segment for turning the arms in and out Fig 2 The length of the segments and therefore the arm lengths and the opening angles of the manipulator arms can be customized to the needed workspace Here we use 50 mm for each segment and an opening angle of 45 for the first segment 60 for the second and 45 for the third segment A spreader mechanism is used to control the first segment for opening arms to achieve sufficient triangulation The degree of opening can be determined via pulling B see Table 1 a ring on the middle of the control panel and is fixed by a locking mechanism with a quick release feature To control the second and third segment for bending the arms in all directions the instrument handles in the control unit can be moved up A and down A in C and out C see Table 1 To reduce the operating forces the instrument handles are connected via a lever Bowden cables using pulling forces realize the force transmission For the second and third segment the principle of double wires is used to enhance the force transmission The movement of the counter rotating cables of the individual segments is coupled whereby the current position of the manipulator arms is fixed when the control unit is held The segments are built of several parts connected with flexure hinges allowing deflection in one direction The flexure hinges have the following dimensions radius mm width mm thickness mm 0 8 0 8 5 first segment 0 5 1 1 5 second segment 0 8 0 8 4 third segment see Fig 2 Experiments on the fatigue strength of flexure hinges are described in 31 Notches are integrated to improve the torsional stiffness of the thinner flexure hinges in the second segment when the arm is loaded Fig 2 This was not necessary for the thicker flexure hinges in the first and third segment Additionally the deflection angle of each flexure hinge is limited to prevent excessive deflection of single flexure hinges to achieve a more uniform deflection and to stabilize the manipulator arms in poses with high deflection In addition the stiffness of the inserted instruments further stabilizes the manipulator arms Figure 2 Monolithic structure of the manipulator arms with rigid shaft 1 grey two channels for instruments 2 one channel for a laparoscope 3 and another channel for an additional instrument 4 Spreader mechanism 5 for opening the arms in the first segment 6 blue second segment 7 green for moving up and down with notches 8 to prevent twisting third segment for bending in and out 9 yellow The flexure hinges 10 geometric parameters radius r width w thickness t allow deflection in one direction with a limited deflection angle The manipulator arms are actuated by Bowden cables red open 11 up 12 down 13 in 14 out 15 The tensile forces required to actuate the manipulator arms depend on the lever arms of the force application points of the Bowden cables the stiffness of the instruments the flexure hinges and the friction of the Bowden cables The manipulator arms are kidney shaped to use the maximum lever lengths for the force application points of the Bowden cables in relation to the cross section of the manipulator shaft Experiments showed that the RotaTip instruments Karl Storz SE interpolated measured operating force for operating the control unit interpolated measured forces for applying the forces at the instrument s tip applicable forces at the instrument s tip The arms are opened without any additional load on the instrument s tip in order to correspond to the procedure for intraoperative use 6300 Further steps can lead to extending the system with a third manipulator arm combine it with augmented reality features as proposed in 30 or integrate it into a robotically controlled system Automated customized adaptation of the system to the working area through automated design can be implemented and the clinical advantages of customized laparoscopic systems should be proofed In summary we developed a 3D printed customizable purely mechanical Single Incision Laparoscopic Manipulator System that can apply the forces needed in SILS ACKNOWLEDGMENT The authors would like to thank the Deutsche Forschungsgemeinschaft DFG for supporting the project LU 604 27 2 REFERENCES 1 B Dong Z Luo J Lu et al Single incision laparoscopic versus conventional laparoscopic right colectomy A systematic review and meta analysis Int J Surg vol 55 pp 31 38 Jul 2018 2 T Mori and G Dapri Reduced Port Laparoscopic Surgery Tokyo Springer Japan 2014 3 D K Kim Y E Yoon W K Han et al Roles of NOTES and LESS in management of small renal masses Int J Surg vol 36 pp 574 582 Dec 2016 4 J J Rassweiler R Autorino J Klein et al Future of robotic surgery in urology BJU Int vol 120 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