A Novel Biodegradable Clip-based Fastening Device for Robotic Minimally Invasive Surgery (MIS): Next Generation Concept for Anastomosis Beyond Suturing and Stapling Tools.

J Opfermann, MS, A Krieger, PhD, PCW Kim, MD, PhD. Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, D.C..

Objective: The task of suturing for anastomosis requires complex coordination of surgical tools and suture management in minimal operative space. The lack of maneuverability and ergonomic design of MIS tools create challenges resulting in longer procedure times, steeper learning curves, surgical fatigue, and higher rates of complication.  Robotic MIS tools increase dexterity and eliminate surgical tremor, but anastomosis is still performed with two tools requiring multiple ports and coordination.  We introduce the design and use of a novel, robotically controlled, laparoscopic clipping tool to better mimic human dexterity while performing MIS anastomosis (See Figure 1).  Our objective is to perform a more efficient and effective anastomosis with respect to leak rate, tensile strength, and bursting pressure.        

Description: The cable-driven laparoscopic clipping tool interfaces with a five axes motor stage, and mounts to a LWR (KUKA) robotic manipulator.  The first two axes drive ±90° articulation joints for improved dexterity within the end effector.  The third axis actuates a forcep to grasp and maneuver tissue, while the fourth axis advances a circular needle through target tissue.  Injection molded bio-absorbable Poly(Lactide-co-Glycolide) (PLGA) clips attach to the needle with a loop. A fifth axis shears the clip from the needle once a clasp is tightened around the clip.  EPOS2 controllers (Maxon Motors) orient DC Brush Motors through CAN communication for precise control.  A quick connect interface facilitates sterilization and easy detachment from the draped robotic positioning system.  Clip and clasp cartridges allow application of eight clips during anastomosis.

Results: Our team developed a prototype clipping tool capable of securing two layers of synthetic tissue (SynDaverTM Labs).  Figure 2 illustrates the clinical work flow to apply a clip and clasp for side to side anastomosis.  Synthetic tissue is first targeted then grasped between the forcep (2a).  Once secure, the needle is advanced beyond the tissue, and the forcep opened (2b).  After repositioning the end effector, a second tissue can be grasped, and the needle with clip advanced through both tissues.  When the clip’s T-shaped foot engages the second tissue (2c), the needle advance and forcep axis synchronize to pull grasped tissue to the top of the clipping tool (2d).  Finally, a clasp is applied to the clip securing the tissues (2e), while simultaneously shearing the clip from the needle.  Using the first prototype tool, we have successfully clipped and clasped two layers of synthetic tissue using a manual technique.

Conclusions:  Herein, we introduce a novel robotic laparoscopic clipping tool with smaller footprint and increased dexterity that simplifies complex two-handed suturing motion.  Initial experience with the clipping tool demonstrated a device capable of applying biodegradable clips and clasps to perform surgical anastomosis.  Presently, work to teleoperate the tool is underway with plans to complete a comparison study between hand suturing, robotically assisted suturing, and clip applied anastomosis.

Figure 1: A novel clipping tool to perform anastomosis during robotic MIS.

          (a)                   (b)                  (c)                   (d)                   (e)
Figure 2: Applying a clip and clasp to two layers of synthetic tissue with the prototype clipping tool.

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