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Purpose: Gastrointestinal cancer can be treated using a flexible endoscope through a natural orifice. However, treatment instruments with limited degrees of freedom (DOFs) require a highly skilled operator. Articulated devices useful for endoluminal procedures, such as endoscopic submucosal dissection and biopsy, have been developed. These devices enable dexterous operation in a narrow lumen; however, they suffer from limitations such as large size and high cost. To overcome these limitations, we developed a 2.5-mm articulated forceps that can be inserted into a standard endoscope channel based on a compliant mechanism. Methods: The compliant mechanism allows the device to be compact and affordable, which is possible due to its monolithic structure. The proposed mechanism consists of two segments, 1-DOF grasping and 2-DOF bending, that are actuated by tendon-sheath mechanisms. A prototype was designed based on finite element analysis results. Results: To confirm the effectiveness of the proposed mechanism, we fabricated the prototype using a 3D printer. A series of mechanical performance tests on the prototype revealed that it achieved the following specifications: (1) DOF: 1-DOF grasping + 2-DOF bending, (2) outer diameter: 2.5 mm, (3) length of the bending segment: 30 mm, and (4) range of motion: 0 ∘ to 20 ∘ (grasping) and - 90 ∘ to + 90 ∘ (bending). Finally, we performed a tissue manipulation test on an excised porcine colon and found that a piece of mucous membrane tissue was successfully resected using an electric knife while being lifted with the developed forceps. Conclusion: The results of the evaluation experiment demonstrated a positive feasibility of the proposed mechanism, which has a simpler structure compared to those of other conventional mechanisms; furthermore, it is potentially more cost-effective and is disposable. The mechanical design, prototype implementation, and evaluations are reported in this paper. [ABSTRACT FROM AUTHOR]

Background and Aims: Colonic endoscopic submucosal dissection (ESD) is time-consuming and bears a high risk of perforation. The aim of the present study was to compare the safety and efficacy between novel articulating devices and conventional ESD in live porcine colon models.Methods: Thirty ESDs in ten pigs were carried out at three different locations (15, 25, and 35 cm from the anus) by the conventional method (n = 15) and by the new method (n = 15). Procedure times, adverse events (perforation, bleeding), and damage to the muscular layer were recorded, and the ESD time per unit area of the specimens was calculated.Results: The perforation rate using the conventional method was 6.7% (1/15), whereas that using the new method was 0.0%. The number of sites of muscular damage was significantly lower in the new than conventional method (6 vs. 37, respectively; P = 0.024). The mean procedure time was significantly shorter in the new than conventional method (4.6 ± 2.0 vs. 7.0 ± 4.1 min/cm2, respectively; P = 0.042).Conclusions: Use of the new ESD method allows for reduced adverse events and a shortened resection time. [ABSTRACT FROM AUTHOR]

Purpose: Image guidance is a key technology that can improve the outcome of laparoscopic surgery. However, due to the large deformation caused by digestive organs, a computer-aided navigation system based on preoperative imaging data cannot indicate the correct target position of the lesion (e.g., liver tumors and vessels invisible from the organ surface). To overcome this issue, we developed a laparoscopic ultrasound manipulator with two motorized degrees of freedom at the tip, allowing for the performance of a dexterous ultrasound scan in a confined laparoscopic surgical area.Method: The developed manipulator consists of a compact and elastic structure using springs, enabling a safe ultrasound scan and avoiding excess force on the inspected organs. The manipulator is a handheld device equipped with four buttons at the handle, which the surgeon directly grasps to send a motion command to the tip structure. The developed prototype realizes two motorized degree-of-freedom motion at the tip. The size of prototype is 15.0 mm in diameter that is usable in conventional laparoscopy. The tip of the manipulator was carefully designed by considering the kinematic model and the results of the finite element analysis.Results: To assess the prototype, accuracy and rigidity were measured by using a motion processing microscope. The accuracy test showed that the proposed device has a fairly accurate characteristic as a handheld device. This was supposedly caused by the nature of compliant mechanism, which does not have mechanical play in motion. In addition, the intrinsic elastic structure (approximately 2.0 N/mm in most of the range of motion) allowed the ultrasound probe to adequately fit on the curved organ surface without extra effort of manipulation during the inspection. In the in vivo experiment, the yaw motion was found to be effective for investigating the vascular network because the manipulator allows the probe to be rotated while maintaining the same position.Conclusion: The mechanical evaluation and in vivo test results showed high feasibility of the prototype. We are currently working on further mechanical improvement for commercialization and development of a real-time navigation system that can perform three-dimensional reconstruction of ultrasonographic images by implementing a magnetic position sensor at the tip of the manipulator. [ABSTRACT FROM AUTHOR]

Background: Difficulties in endoscopic operations and therapeutic procedures seem to occur due to the complexity of operating the endoscope dial as well as difficulty in performing synchronized movements with both hands. We developed a prototype robotic-assisted flexible endoscope that can be controlled with a single hand in order to simplify the operation of the endoscope. The aim of this study was to confirm the operability of the robotic-assisted flexible endoscope (RAFE) by performing endoscopic submucosal dissection (ESD).Methods: Study 1: ESD was performed manually or with RAFE by an expert endoscopist in ex vivo porcine stomachs; six operations manually and six were performed with RAFE. The procedure time per unit circumferential length/area was calculated, and the results were statistically analyzed. Study 2: We evaluated how smoothly a non-endoscopist can move a RAFE compared to a manual endoscope by assessing the designated movement of the endoscope.Results: Study 1: En bloc resection was achieved by ESD using the RAFE. The procedure time was gradually shortened with increasing experience, and the procedure time of ESD performed with the RAFE was not significantly different from that of ESD performed with a manual endoscope. Study 2: The time for the designated movement of the endoscope was significantly shorter with a RAFE than that with a manual endoscope as for a non-endoscopist.Conclusions: The RAFE that we developed enabled an expert endoscopist to perform the ESD procedure without any problems and allowed a non-endoscopist to control the endoscope more easily and quickly than a manual endoscope. The RAFE is expected to undergo further development. [ABSTRACT FROM AUTHOR]

Purpose: In minimally invasive surgery, instruments are inserted from the exterior of the patient's body into the surgical field inside the body through the minimum incision, resulting in limited visibility, accessibility, and dexterity. To address this problem, surgical instruments with articulated joints and multiple degrees of freedom have been developed. The articulations in currently available surgical instruments use mainly wire or link mechanisms. These mechanisms are generally robust and reliable, but the miniaturization of the mechanical parts required often results in problems with size, weight, durability, mechanical play, sterilization, and assembly costs. Methods: We thus introduced a compliant mechanism to a laparoscopic surgical instrument with multiple degrees of freedom at the tip. To show the feasibility of the concept, we developed a prototype with two degrees of freedom articulated surgical instruments that can perform the grasping and bending movements. The developed prototype is roughly the same size of the conventional laparoscopic instrument, within the diameter of 4 mm. The elastic parts were fabricated by Ni-Ti alloy and SK-85M, rigid parts ware fabricated by stainless steel, covered by 3D- printed ABS resin. The prototype was designed using iterative finite element method analysis, and has a minimal number of mechanical parts. Results: The prototype showed hysteresis in grasping movement presumably due to the friction; however, the prototype showed promising mechanical characteristics and was fully functional in two degrees of freedom. In addition, the prototype was capable to exert over 15 N grasping that is sufficient for the general laparoscopic procedure. The evaluation tests thus positively showed the concept of the proposed mechanism. Conclusion: The prototype showed promising characteristics in the given mechanical evaluation experiments. Use of a compliant mechanism such as in our prototype may contribute to the advancement of surgical instruments in terms of simplicity, size, weight, dexterity, and affordability. [ABSTRACT FROM AUTHOR]

The mechanism underlying tissue fusion mediated by laser irradiation remains unclear. We clarify the mechanisms underlying laser-mediated tissue fusion using a novel model. Microscopic examinations of morphological changes within the adventitia of a bovine carotid artery and a collagen sheet prepared from bovine dermis showed collagen fibril bundle loosening and collagen fibre swelling following heating at 46 °C. An incised bovine carotid artery covered with a collagen sheet to which pressure and laser heat of 40 °C–52 °C were applied created a structure that was pressure resistant to >300 mmHg. Microscopic analyses of the irradiation site showed collagen fibril interdigitation. Hence, low-temperature laser-mediated tissue fusion causes collagen fibril bundles to loosen and swell, and crimping causes the fibres to intertwine. As the temperature declines, the loosened and swollen fibrils and fibres tighten, and collagen fibre interdigitation is completed. This technology could be applied to fuse tissues during surgery. [ABSTRACT FROM AUTHOR]