New detachable occlusion balloon unit for transrectal natural orifice translumenal endoscopic surgery.

INTRODUCTION: Transrectal natural orifice translumenal endoscopic surgery (NOTES) requires a good endoluminal view and adequate intrarectal bacterial clearance in the working area. We developed a new occlusion balloon unit with an easily detachable inflation device, which allows the surgeon a clear working area distal to the balloon. MATERIAL AND METHODS: The effectiveness of the sealing balloon and the extent of macroscopic and histopathological injury to the bowel wall at the site of balloon placement were examined in 12 pigs. RESULTS: The mean time to place and inflate the balloon unit was 12.0 ± 3.5 min, effective air-tightness lasted for 21.0 ± 12.0 min. There was no leakage of dye (methylene blue) past the balloon when pressure was maintained >6.70 ± 0.08 kPa (6.62-6.78 kPa). After gut irrigation, good visibility was maintained in the working area for six hours, and adequate bacterial clearance was maintained for three hours. There were no macroscopic signs of intestinal wall damage at the site of balloon placement. Histopathological examination showed only patchy mucosal damage and submucosal thrombus at the site of balloon placement. CONCLUSION: This newly-developed occlusion balloon unit helps to establish good visibility and adequate bacterial clearance for endoluminal surgical procedures.

Development of a robotic system with six-degrees-of-freedom robotic tool manipulators for single-port surgery.

BACKGROUND: Current robotic systems have limitations for single-port surgery (SPS) because the instruments are large, the arms collide and the field of vision requires manual readjustment. We have developed an SPS robotic system that manipulates the vision field. METHODS: The master-slave system included a six degrees of freedom (DOFs) tool manipulator, an easy set-up mechanism, a flexible shaft drive with sufficient DOFs and a vertical arrangement for improved vision. The robot manipulates an endoscope within the body. After assembly, the system was tested in vitro and in vivo. RESULTS: In vitro testing showed that the tool manipulators resected tissue precisely, with the range of motion required. In vivo testing indicated that an abdominal organ is accurately approached and diseased tissue removed by combined endoscopy and robotics. CONCLUSIONS: Our robotics allowed the operator to adjust the vision field intuitively. The tool manipulator approached and resected diseased tissue precisely.

Comparison of transtibial and transportal techniques in drilling femoral tunnels during anterior cruciate ligament reconstruction using 3D-CAD models.

PURPOSE: The purpose of this study was to assess the differences in bone tunnel apertures between the trans-accessory medial portal (trans-AMP) technique and the transtibial (TT) technique in double-bundle anterior cruciate ligament reconstruction. The extent of ovalization and the frequency of overlap of the two tunnel apertures were compared. METHODS: The simulation of femoral tunnel drilling with the TT and the trans-AMP techniques was performed using three-dimensional computer aided design models from two volunteers. The incidence angle of drilling against the intercondylar wall, the femoral tunnel position, the ovalization, and the overlap were analyzed. The aperture and location of the tunnels were also examined in real anterior cruciate ligament reconstruction cases (n=36). RESULTS: The surgical simulation showed that a lower drill incident angle induced by the TT technique made the apertures of two tunnels more ovalized, located anteromedial tunnels in a shallower position to prevent posterior wall blow out, and led to a higher frequency of tunnel overlap. The trans-AMP group had tunnel places within the footprint and had less ovalization and overlap. The results of analysis for tunnels in the clinical cases were consistent with results from the surgical simulation. CONCLUSION: In the TT technique, the shallow anteromedial tunnel location and more ovalized tunnel aperture can lead to a higher frequency of tunnel overlap. Compared with the TT technique, the trans-AMP technique was more useful in preparing femoral tunnels anatomically and avoiding tunnel ovalization and overlapping in double-bundle anterior cruciate ligament reconstruction.

Use of puncture force measurement to investigate the conditions of blood vessel needle insertion.

Central venous catheterization involves venous puncture and catheter insertion for transfusions. Quantitative conditions that facilitate insertion of the needle, such as the angle and velocity of insertion, have not been clarified. We previously developed a robotic system for guiding the needle along a specified puncture path with high precision and are currently implementing a hardware design for a robotic system to assist in blood vessel puncture. In this study, we proposed the insertion angle and velocity for stopping the needle in a blood vessel, assuming that a robotic system such as ours is used during the procedure. We inserted a needle into a segment of porcine jugular vein and obtained the puncture reaction force. Evaluation indices were the magnitude of the sudden decrease in reaction force at the point at which the needle advances and the length of time that the needle is present within the vein. Results indicated that the conditions under which it was easiest to stop the needle inside the vein were an insertion angle range of 10-20 and an insertion velocity of 3mm/s.

Intercondylar roof impingement after anatomic double-bundle anterior cruciate ligament reconstruction in patients with knee hyperextension.

BACKGROUND: Although an anatomically placed graft in anterior cruciate ligament (ACL) reconstruction is reported to have a low risk of roof impingement, which may cause deterioration of the graft or an extension deficit, the incidence of roof impingement by these grafts has not been evaluated in hyperextensible knees. PURPOSE: To evaluate the incidence of roof impingement by the native ACL in hyperextensible knees and to examine the risk of roof impingement by anatomic placement of the ACL graft in hyperextensible knees. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve patients were selected for a hyperextensible knee group (group A), defined as having hyperextension of the knee of greater than 10°. Twelve patients were recruited to a normal extension knee group (group B) with normal extension of the knee of less than 5° of hyperextension. Magnetic resonance imaging (MRI) scans of the knee positioned in 30° of flexion and full extension were acquired from all patients. The shape of the native ACL at full extension was compared between the groups. A 3-dimensional (3D) bone model was created from the acquired 2D MRI scans. A virtual anatomic double-bundle ACL reconstruction in each patient and a virtual anatomic single-bundle reconstruction in the patients in group A were performed using the 3D MRI bone models. The volume of the overlap between the graft and roof was calculated to evaluate graft impingement in each instance. RESULTS: The MRI scans showed posterior bowing of the native ACL in the group A knees. The simulated double-bundle ACL reconstruction showed that the overlapped volume was significantly greater in patients in group A than in patients in group B (P < .05). However, the overlap of the simulated single-bundle ACL reconstruction was significantly less than for the double-bundle ACL reconstruction (P < .05). CONCLUSION: To reduce the risk of roof impingement by the graft, single-bundle ACL reconstruction with the graft placed at the center of the footprint might be the better method for patients with a hyperextensible knee than an anatomic double-bundle ACL reconstruction. CLINICAL RELEVANCE: It is recommended that surgeons cautiously consider roof impingement after anatomic double-bundle ACL reconstruction in patients with a hyperextensible knee.

Development of a 6-DOF manipulator driven by flexible shaft for minimally invasive surgical application.

This paper presents a 6-DOF manipulator which consists of four parts, 1-DOF translational joint, two 2-DOF bending joints (segment1 and segment2), and 1-DOF rotational gripper. The manipulator with "flexible shaft and Double Screw Drive (DSD) mechanism" structure can obtain omni-directional bending motion through rotation of flexible shafts. In the first prototype, the flexible shafts were connected directly with the actuators in the manipulator. Compared with the first prototype, in the second prototype, flexible shafts for power transmission are connected to the base of the manipulator. Universal joints are used for power transmission to realize distal motion. The improvement done with the design of the second prototype reduced the torque necessary to drive the flexible shafts during motion in surgical interventions. Experiment results show that the manipulator has enough range of movement for surgical intervention.

The concept and feasibility of EXPERT: intelligent armrest using robotics technology.

BACKGROUND: Continuous precise motions are required in microneurosurgery to provide high-quality surgical results. Stabilizing the surgeon's arm and reducing fatigue during surgery are expected to improve the precision of microsurgical procedures. We have developed an intelligent armrest, EXPERT, that follows the surgeon's hand and fixes at an adequate position automatically using robotics technology. OBJECTIVE: To understand the feasibility of EXPERT by using the system in laboratory experiments and clinical situations. METHODS: EXPERT has an arm holder and acts as a passive controlled robot with 5 degrees of freedom. The system has 3 modes: transfer, arm-holding, and arm-free mode, which are selected automatically. In the transfer mode, the arm holder follows the surgeon's arm. In the arm-holding mode, EXPERT supports the surgeon's arm weight by fixing the arm holder. The surgeon can move his/her arm away from the arm holder in the arm-free mode. The surgeon can change the position of armrest while looking through the microscope and can continue the microsurgical procedure while holding surgical instruments. Since 2010, EXPERT has been applied in 13 surgeries. RESULTS: The EXPERT system decreased surgeon fatigue and reduced difficulty in performing surgical procedures. The EXPERT system markedly reduced surgeon hand tremor. There were no complications related to the use of this system. CONCLUSION: EXPERT is a useful tool for holding the surgeon's arm comfortably and following the surgeon's arm automatically.

In vivo experiments of a surgical robot with vision field control for Single Port Endoscopic Surgery.

Recently, robotics systems are focused to assist in Single Port Endoscopic Surgery (SPS). However, the existing system required a manual operation of vision and viewpoint, hindering the surgical task. We proposed a surgical endoscopic robot for SPS with dynamic vision control, the endoscopic view being manipulated by a master controller. The prototype robot consists of a manipulator for vision control, and dual tool tissue manipulators (gripping: 5DOFs, cautery: 3DOFs) can be attached at the tip of sheath manipulator. In particular, this paper focuses on an in vivo experiment. We showed that vision control in the stomach and a cautery task by a cautery tool could be effectively achieved.

Design of a surgical robot with dynamic vision field control for Single Port Endoscopic Surgery.

Recently, a robotic system was developed to assist Single Port Endoscopic Surgery (SPS). However, the existing system required a manual change of vision field, hindering the surgical task and increasing the degrees of freedom (DOFs) of the manipulator. We proposed a surgical robot for SPS with dynamic vision field control, the endoscope view being manipulated by a master controller. The prototype robot consisted of a positioning and sheath manipulator (6 DOF) for vision field control, and dual tool tissue manipulators (gripping: 5DOF, cautery: 3DOF). Feasibility of the robot was demonstrated in vitro. The "cut and vision field control" (using tool manipulators) is suitable for precise cutting tasks in risky areas while a "cut by vision field control" (using a vision field control manipulator) is effective for rapid macro cutting of tissues. A resection task was accomplished using a combination of both methods.

A surgical robot with vision field control for single port endoscopic surgery.

BACKGROUND: Robotic end-effectors for single port endoscopic surgery (SPS) require a manual change of vision field that slows surgery and increases the degrees of freedom (DOFs) of the manipulator. METHODS: A new surgical prototype robot has dynamic vision field control and a master controller to manipulate the endoscopic view. It uses positioning (4 DOF) and sheath (2 DOF) manipulators for vision field control, and dual tool tissue manipulators (gripping, 5 DOF; cautery, 3 DOF). RESULTS: The robot is feasible in vitro. 'Cut and vision field control' (using tool manipulators) was suitable for precise cutting tasks in risky areas; 'cut by vision field control' (using the vision field control manipulator) was effective for rapid macro cutting of tissues. A resection was performed using a combination of both methods. CONCLUSIONS: The novel robotic system is feasible, but further studies are needed to address its performance in vivo.

Autonomous avoidance based on motion delay of master-slave surgical robot.

Safe use of master-slave robots for endoscopic surgery requires autonomous motions to avert contact with vital organs, blood vessels, and nerves. Here we describe an avoidance control algorithm with delay compensation that takes the dynamic characteristics of the robot into account. To determine the operating parameters, we measured frequency characteristics of each joint of the slave-manipulator. The results suggest this delay compensation program improves avoidance performance.

Telesurgery of Microscopic Micromanipulator System "NeuRobot" in Neurosurgery: Interhospital Preliminary Study.

OBJECT: Robotic surgery can be applied as a novel technology. Our master-slave microscopic-micromanipulator system (NeuRobot), which has a rigid endoscope and three robot-arms, has been developed to perform neurosurgical procedures, and employed successfully in some clinical cases. Although the master and slave parts of NeuRobot are directly connected by wire, it is possible to separate each part and to apply it to telesurgery with some modifications. To evaluate feasibility of NeuRobot in telesurgery, some basic experiments were performed. METHODS: The quality of telemedicine network system between Shinshu University and one of the affiliated hospitals, which was completely separated from other public network systems, was investigated. The communication delay was calculated from the transmitting and the receiving records in the computers set in each hospital. The relationship between the change in communication delay from the master part to the slave part of NeuRobot (0, 100, 300, 500 and 700 ms) respectively and feasibility of NeuRobot was investigated. The task performance time in each time changing group was compared. Feasibility of NeuRobot in telesurgical usage was evaluated. The master part and the slave part of NeuRobot placed in each hospital were connected through private network system. Interhospitally connected NeuRobot was compared with directly connected one in terms of task performance time. RESULTS: Less than 1 ms was required for corresponding the data in a steady transmitting state. Within 2 seconds after connection, relative time delay (maximum 40 ms) and packet loss were sometimes observed. The mean task performance time was significantly longer in over 500 ms delayed group compared with directly connected NeuRobot. There was no significant difference in the task performance time between directly connected NeuRobot and interhospitally connected NeuRobot. CONCLUSION: Our results proved that telesurgical usage of NeuRobot was feasible. Telesurgical usage of telecontrolled manipulator system is recommended for application in a private network system in order to reduce technical and ethical problems. Some technical innovations will bring breakthrough to the telemedicine field.