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Technical Brief

Lowering the Barrier of Surgical Endoscopy With a Novel Articulating Retractor

[+] Author and Article Information
Neil A. Ray

Department of Surgery,
University of California, San Francisco,
550 16th Street, 5th Floor,
San Francisco, CA 94143
e-mail: neilray92@gmail.com

Dillon Kwiat, Stanley Rogers, Matthew Y. C. Lin

Department of Surgery,
University of California, San Francisco,
550 16th Street, 5th Floor,
San Francisco, CA 94143

Manuscript received June 12, 2016; final manuscript received February 18, 2017; published online June 27, 2017. Assoc. Editor: Elizabeth Hsiao-Wecksler.

J. Med. Devices 11(3), 034501 (Jun 27, 2017) (6 pages) Paper No: MED-16-1238; doi: 10.1115/1.4036136 History: Received June 12, 2016; Revised February 18, 2017

Surgical endoscopy has gained traction over the past several decades as a viable option for therapeutic interventions in the gastrointestinal tract. It utilizes natural orifice access which shortens hospital stay, minimizes patient discomfort, and decreases overall healthcare costs. However, the inability to effectively retract and position target tissue is a significant limitation for these procedures. Current instruments are unable to triangulate and can only be manually withdrawn or advanced through the channels. There is a need to provide better access and control of soft tissue to be able to perform more complex and complete endoscopic resections. We have developed a novel device to provide optimal tissue retraction for endoscopic procedures. Our device consists of an articulating tissue retractor and a specialized handle. Two articulating curves were created that can manipulate the position and direction of the retractor tip. Each curve is independently adjusted by locking thumb sliders, allowing for increased range of motion and retraction independent of endoscope position. With a diameter of 2.8 mm, the proposed device can be used in current endoscopic equipment. Preliminary testing showed that our retractor has comparable slip strength to a commercially available device (1.13 N ± 0.53 N versus 1.10 N ± 0.51 N, p-value: 0.416), but has much greater range of motion (maximum deflection of 72 deg compared to 0 deg). This increased range of motion allows the articulating grasper to better triangulate and preserve visualization of the dissection plane, allowing it to overcome the most significant barrier restricting endoscopic surgery.

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Figures

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Fig. 1

solidworks model of the complete prototype

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Fig. 2

Top: an artist rendition of how the articulating endoscopic retractor will function. Four degrees of freedom shown. Below: an artistic rendition of the view through the endoscopic camera, allowing for full visualization of the resection plane.

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Fig. 3

Retractor design and specifications. Two articulating points allow for increased range of motion.

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Fig. 4

Metal prototype of the retractor

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Fig. 5

Handle design and specifications. Each thumb slider controls one articulating curve, while the side sliders are used to lock each curve in place. The jaw trigger opens and closes the grasper, and the jaw tab holds the jaw in place.

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Fig. 6

Previous handle prototype 3D printed using ABS plastic. It is designed for single-hand operation.

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Fig. 7

Internal mechanics of one-half of the handle: (a) The curve actuation is governed by a gear rack mechanism that can be locked by the side slider, which engages a metal spring into the gear teeth. The jaw trigger and tab both have interlocking teeth which can be used to lock the jaw in a position. In this example, additional components needed for jaw functioning have been omitted for clarity. (b) The ventral view of the device is shown to demonstrate the peg on the gear where the control wire will attach.

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Fig. 8

Experimental setup for slip strength testing. Left: testing was conducted with conventional retractor. Right: testing was conducted with the novel articulating retractor.

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Fig. 9

Experimental setup for distal tip angle testing. The articulating retractor is shown here at baseline position.

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Fig. 10

Box-and-whisker plot of the peak slip force for both retractors by tissue type. The horizontal line represents the mean value for each data set.

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Fig. 11

Distal tip deflection for both conventional and articulating retractors: (a) the maximum deflection when activating curve 1, (b) the maximum deflection when activating curve 2, (c) the maximum deflection when activating both curves 1 and 2, and (d) the range of motion of an immobilized conventional retractor

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Fig. 12

This image is a visual comparison of the full range of motion for each curve: (a) full range of motion for curve 2, (b) full range of motion for curves 1 and 2, (c) full range of motion for curve 1, and (d) full range of motion for the conventional retractor [13]

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