ABSTRACT
Objective To analyze the relationship of closed staple height with tissue damage and compression pressure, so as to provide theoretical references and guidance for the surgeon to choose the appropriate staple cartridge and height, as well as improve the safety of operation. Methods The finite element model of stapled colorectal end-to-end anastomosis was established based on analysis of staple-tissue interaction. Large intestine tissues with different wall thicknesses (1.0-1.5 mm) were compressed by closed staples with 4 different height to compare changes in stress distributions and average radial pressure. Results When the tissues were compressed by closed staple with height of 1.0, 1.1, 1.2 and 1.5 mm, respectively, the average radial stress of compressed tissues with wall thicknesses of 1.2, 1.3, 1.4, and 1.5 mm were 56.0, 58.6, 59.7 and 57.3 kPa, respectively, which was close to the optimal compression pressure. Stress concentrations were found in contact area of the staple and tissues，with the maximum stress being 2 783, 1 750, 1940 and 2 030 kPa, respectively. Conclusions Tissue damage cannot be completely avoided in anastomotic surgery, and stress concentration is generally located near contact region of the staple and tissues. The optimal closed staple height ranges in 50%-60% of the uncompressed tissue height.
ABSTRACT
By developing a novel endoscopic succession closing device to overcome the shortcomings of existing devices that cannot deploy several clips at a time, to perform structural analysis on different clamp structures and to validate their performances in tissue closure through finite element analysis. Methods Comparative analyses of three clamp structures, namely, the aligning tooth structure (original, clamp A), the staggered tooth structure (clamp B), a combination structure with page break angle and staggered tooth (clamp C), were performed to analyze pressure and its distribution on tissues when clamping the stomach wall. Displacement of 7.5 mm was then applied on the clamps to simulate the effect of the operating procedures of the device and tissue kick-back. Results The maximum stresses of the clamp A and B were located on the first pair of teeth which was closest to the rotating shaft, with the stress being 10.39 kPa and 10.11 kPa, respectively. The maximum stress (11.35 kPa) of the clamp C was located on the second pair of teeth. For clamp A and B, the longer the distance to shaft, the larger pressure on stomach tissues. While for clamp C, the pressure on device-tissue interface showed little change along the path. Under tensile displacement, clamp A and B slipped off from the tissue when displacements reached to 5 mm and 6.5 mm, respectively, while clamp C did not. Conclusions Clamp with page break angle and staggered tooth can exert the uniform max pressure to tissues and provide a larger contact area away from the rotating shaft, thus improving anti-slippage and performance of the novel endoscopic closing device.
ABSTRACT
Objective By developing a novel endoscopic succession closing device to overcome the shortcomings of existing devices that cannot deploy several clips at one time,to perform structural analysis on different clamp structures and to validate their performances in tissue closure through finite element analysis.Metbods Comparative analyses of 3 clamp structures,namely,the aligning tooth structure (original,clamp A),the staggered tooth structure (clamp B),a combination structure with page break angle and staggered tooth (clamp C),were performed to analyze pressure and its distribution on tissues when clamping the stomach wall.Displacement of 7.5 mm was then applied on the clamps to simulate the effect from operating procedures of the device and tissue kick-back.Results The maximum stresses of the clamp A and B were located on the first pair of teeth which was closest to the rotating shaft,with the stress of 10.39 kPa and 10.11 kPa,respectively.The maximum stress (11.35 kPa) of the clamp C was located on the second pair of teeth.For clamp A and B,the longer the distance to shaft,the larger pressure on stomach tissues.While for clamp C,the pressure on device-tissue interface showed little change along the path.Under tensile displacement,clamp A and B slipped off from the tissue when displacements reached to 5.0 mm and 6.5 mm,respectively,while clamp C did not slip off.Conclusions Clamp with page break angle and staggered tooth can exert the uniform maximum pressure to tissues and provide a larger contact area away from the rotating shaft,thus improving the anti-slippage and performance of the novel endoscopic closing device.
ABSTRACT
Objective By developing a novel endoscopic succession closing device to overcome the shortcomings of existing devices that cannot deploy several clips at one time,to perform structural analysis on different clamp structures and to validate their performances in tissue closure through finite element analysis.Metbods Comparative analyses of 3 clamp structures,namely,the aligning tooth structure (original,clamp A),the staggered tooth structure (clamp B),a combination structure with page break angle and staggered tooth (clamp C),were performed to analyze pressure and its distribution on tissues when clamping the stomach wall.Displacement of 7.5 mm was then applied on the clamps to simulate the effect from operating procedures of the device and tissue kick-back.Results The maximum stresses of the clamp A and B were located on the first pair of teeth which was closest to the rotating shaft,with the stress of 10.39 kPa and 10.11 kPa,respectively.The maximum stress (11.35 kPa) of the clamp C was located on the second pair of teeth.For clamp A and B,the longer the distance to shaft,the larger pressure on stomach tissues.While for clamp C,the pressure on device-tissue interface showed little change along the path.Under tensile displacement,clamp A and B slipped off from the tissue when displacements reached to 5.0 mm and 6.5 mm,respectively,while clamp C did not slip off.Conclusions Clamp with page break angle and staggered tooth can exert the uniform maximum pressure to tissues and provide a larger contact area away from the rotating shaft,thus improving the anti-slippage and performance of the novel endoscopic closing device.
ABSTRACT
Objective To design a novel endoscopic successive hemostasis and closing device, and to validate whether the device can meet the needs of tissue closure by finite element analysis. Methods By using the novel device, the target tissue was clamped and the clip was then pushed to pierce the tissue. Under the compression between the clip and the inner side of the grasper, the thinner arms of the clip were forced to bend and close to stay in the tissue, and then the inverse displacement of 2 mm was applied on the clip. The elastic limit and tensile strength of the clip were set as 239.0 and 901.0 MPa, respectively. Results Deformation did not occur in the piercing process of the clip, with the maximum stress of 212.6 MPa. The deformed shape of the clip in the bending process matched its design expectation, with the maximum stress of 727.7 MPa. The maximum stress of the clip was 75.8 MPa under 2-mm inverse displacement. Material failure was not found in the bending process or with 2-mm inverse displacement, and the maximum stress in the whole process was 741.0 MPa. Conclusions The novel endoscopic successive hemostasis and closing device proposed in this study can deploy 4 clips at one time, together with an independent grasper for gathering tissues, which can shorten the reloading time and improve the accuracy of clip deployment. The effectiveness and safety of the device is also proved by using finite element method.