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Design of a new suturing and knot tying device for laparoscopic surgery

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Title:
Design of a new suturing and knot tying device for laparoscopic surgery
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English
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Onal, Sinan
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University of South Florida
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Dissertations, Academic -- Industrial & Management Systems Engineering -- Masters -- USF   ( lcsh )
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Abstract:
ABSTRACT: Minimally invasive or laparoscopic surgery has completely changed the focus of surgery becoming an alternative to various types of open surgery. Minimally invasive surgery avoids invasive open surgery as the operation is performed through one or more small incisions in the abdomen and using a small camera called laparoscope. Through these incisions, surgeons insert specialized surgical instruments to perform the operation resulting in less postoperative pain, shorter hospital stay, and faster recovery. However, the main problems during minimally-invasive surgery are the limited space for operating instruments and the reduced visibility and range of motion inside the patient's body. During minimally-invasive surgery, one of the most difficult and time consuming surgical procedures is suturing and knot tying. This procedure significantly increases the operation time as it requires advanced techniques and extensive experience by surgeons. The main goal of this research is to investigate, design, and develop a new suturing instrument to facilitate suturing procedures during minimally invasive surgery. Qualitative research data was collected through interviews with a surgeon and six in-depth observations of minimally invasive surgeries at Tampa General Hospital. Different design concepts and mechanisms were created using SolidWorks CAD software, and tested using SimulationXpress in order to identify dimensions, materials and expected performance of the design and its components. The prototypes of the device were made using a Dimension SST 768 FDM machine and tested by the surgeon to ensure that the final design meets the specified needs and criteria. This new device will eliminate the use of many different devices during the operation and allow the use of any type of suture. The proposed suturing device aims to benefit both patients and surgeons. For surgeons, the new device aims to decrease the number of steps for laparoscopic suturing through an intuitive and ergonomic design. For patients, the proposed device will reduce time during surgery and under general anesthesia leading towards improved health care.
Thesis:
Thesis (MSEM)--University of South Florida, 2010.
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Includes bibliographical references.
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by Sinan Onal.
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ABSTRACT: Minimally invasive or laparoscopic surgery has completely changed the focus of surgery becoming an alternative to various types of open surgery. Minimally invasive surgery avoids invasive open surgery as the operation is performed through one or more small incisions in the abdomen and using a small camera called laparoscope. Through these incisions, surgeons insert specialized surgical instruments to perform the operation resulting in less postoperative pain, shorter hospital stay, and faster recovery. However, the main problems during minimally-invasive surgery are the limited space for operating instruments and the reduced visibility and range of motion inside the patient's body. During minimally-invasive surgery, one of the most difficult and time consuming surgical procedures is suturing and knot tying. This procedure significantly increases the operation time as it requires advanced techniques and extensive experience by surgeons. The main goal of this research is to investigate, design, and develop a new suturing instrument to facilitate suturing procedures during minimally invasive surgery. Qualitative research data was collected through interviews with a surgeon and six in-depth observations of minimally invasive surgeries at Tampa General Hospital. Different design concepts and mechanisms were created using SolidWorks CAD software, and tested using SimulationXpress in order to identify dimensions, materials and expected performance of the design and its components. The prototypes of the device were made using a Dimension SST 768 FDM machine and tested by the surgeon to ensure that the final design meets the specified needs and criteria. This new device will eliminate the use of many different devices during the operation and allow the use of any type of suture. The proposed suturing device aims to benefit both patients and surgeons. For surgeons, the new device aims to decrease the number of steps for laparoscopic suturing through an intuitive and ergonomic design. For patients, the proposed device will reduce time during surgery and under general anesthesia leading towards improved health care.
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Design of a New Suturing and Knot Tying Device for Laparoscopic Surgery by Sinan Onal A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Engineering Management Department of Industrial and Management System s Engineering College of Engineering University of South Florida Major Professor: Susana Lai Yuen, Ph.D. Stuart Hart, M D Patricia Zarate, Ph.D. Date of Approval: June 30 2010 Keywords: suturing device, laparoscopy, hysterectomy, medical device design, prototype Copyright 2010, Sinan Onal

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Acknowledgments I would like to express my heartfelt gratitude to my advisor, Dr. Susa na Lai Yuen for her supervision, and guidance from the very early stage s of this research She has always provided me constant encouragement and support in various ways in my journey of growing into the researcher and scientist that I want to be I am indebted to her more than s he knows. My sincere thanks also go to Dr. Stuart Hart for his advice and crucial contribution to this study which made him a backbone of this research. His involvement with his expertise in this area has triggered and nourished mine. Above all, this thesis would have not been possible, had he not given me the opportunity to observe his operations. Likewise, Dr. Patricia Zarat e deserve s special thanks as another member of my committee. Her being accessible and approachable as well as her instant support when I am in need have helped me e xperience a smoother and more fruitful process throughout this study I would also acknowledge my friends Issa Ramirez, Gokmen Demirkaya, Ricardo Vasquez Padilla and Humberto Gomez for their willingness to share their ideas with me. Last but not least, w ords fail me to express my appreciation to my wife Derya whose unconditional love and support, and persistent confidence in me, has taken the load off my shoulder and to my one and only daughter, Pera, the reason of my life, for simply cheering it up and making it more m eaningful with her presence every passing day I would not be here today without them and their love.

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i Table of Contents List of Tables ................................ ................................ ................................ ................. iii List of Figures ................................ ................................ ................................ ................ iv Abstract ................................ ................................ ................................ ......................... vii Cha pter 1: Introduction ................................ ................................ ................................ .... 1 1.1 Motivation ................................ ................................ ................................ ...... 1 1.2 Thesis Objectives and Contributions ................................ ............................... 5 1.3 Thesis Outline ................................ ................................ ................................ 6 Chapter 2 : Literature Review ................................ ................................ ........................... 7 2.1 Conventional L aparoscopic Suturing and Knot Tying Process ........................ 7 2.2 Commercially Available Suturing Devices ................................ ................... 12 2.2.1 Endo Stitch 10 mm Suturing Device ................................ .......... 12 2. 2.2 Capio Open Access and Standard Suture Capturing Device ......... 14 Chapter 3: Case Study on Conventional Suturing Process ................................ .............. 18 3.1 Human Factors Engineering ................................ ................................ ......... 18 3.2 Introduction to Case Study ................................ ................................ ........... 19 3.3 Laparoscopic Instruments U sed for Suturing and Knot Tying ....................... 19 3.4 Task Analysis ................................ ................................ .............................. 21 3.5 Failure Mode and Effect Analysis (FMEA) ................................ .................. 25 Chapter 4: Design Process of the Proposed Laparoscopic Suturing Device .................... 29 4.1 Definition of Medical Device and Design Process ................................ ........ 29 4.2 Analysis Stage ................................ ................................ .............................. 31 4.2.1 Analysis of the Problem ................................ ................................ 32 4.2.2 Product Design Specification s ................................ ........................ 33 4.3 Synthesis Stage ................................ ................................ ............................ 36 4.3 .1 Developing Alternative Solutions ................................ ................... 36 4.3 .2 Choosing a Solution ................................ ................................ ....... 38 4.4 Evaluation Stage ................................ ................................ .......................... 40 4.4.1 Modeling and Engineering Analysis ................................ ............... 41 4.4.2 Prototyping and Evaluating ................................ ............................ 58 Chapter 5: Research Summary and Future Work ................................ ............................ 65

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ii 5.1 Research Summary ................................ ................................ ....................... 65 5.2 Future Research Work ................................ ................................ .................. 66 References ................................ ................................ ................................ ..................... 67

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iii List of Tables Table 3.1: Task a nalysis for conventional suturing p rocess ................................ ...... 22 T able 3.2: Failure mode and ef fect a nalysis for conventional suturing p rocess ......... 26 Table 3.3: Severity ranking c riteria ................................ ................................ ......... 28 Table 3.4: Probability ranking c riteria ................................ ................................ ..... 28 Table 4 .1 : Product design s pecifications ................................ ................................ .. 3 5 Table 4 .2 : Pugh c hart ................................ ................................ .............................. 40 Table 4.3: Types of m aterial ................................ ................................ .................... 44

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iv List of Figures Figure 1.1 : Minimally invasive surgery [drawing] ................................ ...................... 2 Figure 1.2 : 2D monitoring during minimally invasive surgery [drawing] .................... 2 Figure 1.3: 12 mm l aparoscopic port [photograph] ................................ ..................... 4 Figure 2.1 : Curved needle with surgical suture [photograph] ................................ ...... 8 Figure 2.2: Laparoscopic needle driver [photograph] ................................ .................. 8 Figure 2.3: Maryland g rasper [photograph] ................................ ................................ 8 Figure 2.4: Extra corporeal knot tying technique ................................ ........................ 9 Figure 2.5: Knot pusher [photograph] ................................ ................................ ......... 9 Figure 2.6: Half hitches knot techniques ................................ ................................ .. 10 Figure 2.7: Compound sliding knots ................................ ................................ ......... 11 Figure 2. 8 : Intra corporeal su turing and intra corporeal knot tying t echnique ........... 12 Figure 2.9 : m suturing d evice [photograph] ................................ 13 Figure 2.10 : Knot tying technique with Endo Stitch ................................ ................ 14 Figure 2.11 : Capio s uture c apturing d evice [drawing] ................................ .............. 15 Figure 2.12: Partial schematic perspective views of distal portion of Capio [drawing ] ................................ ................................ ................................ 16 Figure 2.13 : Transvaginal and paravagin al defect repair using the Capio ................ 17 Figure 3.1 : Instruments used for conventional laparoscopic suturing and knot tying ................................ ................................ ................................ ....... 20 Figure 4.1 : Product development p rocess ................................ ................................ .. 30

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v Figure 4.2: Product development process for the proposed device ............................ 31 Figure 4.3: Su b steps of the analysis stage ................................ ................................ 31 Figure 4.4: Sub steps of the synthesis stage ................................ .............................. 36 Figure 4.5 : A lternative design 1 ................................ ................................ ................ 37 Figure 4.6 : A lternative design 2 ................................ ................................ ................ 37 Figure 4.7 : Alternative design 3 ................................ ................................ ................ 38 Figure 4.8 : Alternative design 4 ................................ ................................ ................ 38 Figure 4.9 : Alternative design 5 ................................ ................................ ................ 38 Figure 4.10 : Design decision factors ................................ ................................ ........... 39 Figure 4.11: Sub steps of the evaluation stage ................................ ............................ 41 Figure 4.1 2 : 3D CAD model of the proposed device ................................ ................... 42 Figure 4.13 : Mechanism for needle transporting of the proposed device ..................... 43 Figure 4.14 : Arms at the tip of the proposed device ................................ .................... 46 Figure 4.15 : FEA results of stress distribution in the arms of the device ..................... 47 Figure 4.16 : Displacement distribution in the arms and deformed shape of the arms ................................ ................................ ................................ ....... 4 8 Figure 4.17 : The flexible wire to control the needle carriers ................................ ....... 49 Figure 4.18 : Small plunger ................................ ................................ ......................... 49 Figure 4.19 : Main p lunger ................................ ................................ .......................... 49 Figure 4.20 : Relationship between the main plunger and small plunger ...................... 50 Figure 4.21 : Detailed view of the mechanism for changing the needle direction ......... 51 Figure 4.22 : Stress distribution on the small plunger and deformed shape of the part ................................ ................................ ................................ ......... 53 Figure 4.23 : Displacement distribution on the arms of the small plunger .................... 53

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vi Figure 4.24 : Stress distribution on the main plunger and deformed shape of the part ................................ ................................ ................................ ......... 54 Figure 4.25 : Displacement distribution on the arms of the small plunger .................... 55 Figure 4.26 : Needle and needle carrier ................................ ................................ ....... 56 Figure 4.27 : Needle holder ................................ ................................ ......................... 56 Figure 4.28 : Stress distribution on the needle holder ................................ ................... 57 Figure 4.29: Fused deposition modeling (FDM) machine Dimension SST 768 .......... 58 Figure 4.30: Prototype s of the first version of the handle ................................ ............ 59 Figure 4.31: Prototype of th e final version of the handle ................................ ............. 60 Figure 4.32: Prototype of the first version of the arms ................................ ................ 61 Figure 4.33: Prototype of the final version of the arms ................................ ................ 61 Figure 4.34: Prototype of the final version of the arms assembled .............................. 62 Figure 4.35: Prototype of the fina l version of the toggle lever ................................ ..... 63 Figure 4.36: Prototype of the main plunger and small plunger ................................ .... 63 Figure 4.37: Prototype of th e main plunge r and small plunger assembled ................... 63 Figure 4.38: Prototype of th e final flexible wire ................................ .......................... 64 Fi gure 4.39: Prototype of the final v ersion of the proposed device .............................. 64

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vii Design of a New Suturing and Knot Tying Device for Laparoscopic Surgery Sinan Onal A bstract Minimally invasive or laparoscopic surgery has completely changed the focus of surgery becoming an alternative to various types of open surgery. Minimally invasive surgery av oids invasive open surgery as the operation is performed through one or more small incisions in the abdomen and using a small camera called laparoscope. Through these incisions, surgeons insert specialized surgical instruments to perform the operation res ulting in less postoperative pain, shorter hospital stay, and faster recovery. However, the main problems during minimally invasive surgery are the limited space for operating body. During minimally invasive surgery, one of the most difficult and time consuming surgical procedures is suturing and knot tying. This procedure significantly increases the operation time as it requires advanced techniques and extensive experience by surgeons. The main goal of this re search is to investigate, design, and develop a new suturing instrument to facilitate suturing procedures during minimally invasive surgery. Qualitative research data was collected through int erviews with a surgeon and six in depth observations of minimally invasive surgeries at Tampa General Hospital. Different design concepts and mechanisms were created using SolidWorks CAD software, and tested using SimulationXpress in order to identify dimensions, materials and expected

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viii performance of the design and its components. The prototypes of the device were made using a Dimension SST 768 FDM machine and tested by the surgeon to ensure that the final design meets the specified needs and criteria. This new device will eliminate the use of many different devices during the operation and allow the use of any type of suture. The proposed suturing device aims to benefit both patients and surgeons. For surgeons, the new device aims to decrease the number of steps for laparoscopic suturin g through an intuitive and ergonomic design. For patients, the proposed device will reduce time during surgery and under general anesthesia leadin g towards improved health care.

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1 Chapter 1 Introduction This chapter introduces the motivation underneath this research work and the current challenges in minimally invasive surgical procedures. The research objectives are presented followed by the thesis outline. 1.1 Motivation Minimally invasive surgery (MIS) or laparoscopic surgery has changed the focus of surgery becoming an alternative to various types of open surgery Minimally invasive surgery is a new surgery technique that avoids invasive open surgery by operating through small incisions in the abdomen and using a small camera called laparoscope as shown in Figure 1 .1 The small incisions measure about 6.5 12.7 m m in size compared to the minimum incision size of 20 cm required for traditional open surgery techniques ("Minimally invasive", 2 010) Through these incisions, surgeons insert specialized surgical instruments to perform the operation while observing the working space through a video monitor as shown in Figure 1.2. For this reason, minimally invasive surgery results in less tissue trauma, less scarring, and faster post operative recovery time.

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2 Figure 1. 1 : Minimally invasive surgery [drawing]. Retrieved January 10, 2010 from www.rfay.com.au/laparoscopic Figure 1.2: 2D monitoring during minimally invasive surgery [drawing]. Retrieved January 10 from www.rfay.com.au/laparoscopic According to the U.S. Department of Health and Human Services, it is estimated that in 2008 there were around 220,000 gastric bypass procedures and more than 250,000

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3 appendectomies performed in the Un ited States. Also, about 50,000 patients in the United States are diagnosed each year with liver metastases that requir e a liver resection procedure. Furthermore, hysterectomies are the second most common surgery performed among women in the United States, with over 600,000 op erations carried out each year and w hi le up to 7 5 % of hysterectomies are pe rformed through open surgeries (Dunitz, Sheth, & Studd, 2002) T he percentage of laparoscopic hysterectomies is increasing and will greatly benefit from new improved instruments that facilitate this type of surgery There are several benefits of minimally invasive surgery over traditional methods. The most important benefit is that post operative scars are much smaller than those that occur as a result of conventional "open" surgery thus resulting in less pain for the patient Single incision minimally invasive surgery leaves minimal scar because the surgery is performed through a single incision in the belly button. Patients require less pain medication and recover faster, normally returning home w ithin 24 hours after their surgery. This is a major advantage when compared with hospital stays of 2 to 5 days from open surgery patients. In recent years minimally invasive surgery has developed in a way that it is now being used to perform a variety of procedures such as gastric bypass, appendectomy, liver resection, hysterectomy, and more. Although minimally invasive surgery has become increasingly popular, the problems pertaining to it, such as limited visibility, constrained working space, and the use of high end techno logical tools, still complicate the surgery. Surgeons need to obtain extensive training to be qualified to perform minimally invasive surgeri e s and not all hospitals have the special equipment necessa ry to perform such surgeries In addition, the design of medical tools for minimally invasive surgery is

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4 constrained by the size of the ports used to insert the surgical instruments. These ports normally have an opening of 5 12 mm in diameter where the surgical instruments are inserted to perform a laparoscopic surgery Therefore, surgical tools need to be small enough to fit through these ports making the design of these tools a challenge. Figure 1. 3 : 12 mm l aparoscopic port [photograph] Retrieved February 6, 2010 from: http://www.laparoscopytoday.com/pediatricsurgery/page/3/ During a laparoscopic surgery, suturing and knot tying are among the most difficult and most time consuming procedures. These procedures significantly increase the operation time as they require adv anced techniques and extensive experience by surgeons due to the limited operating space and motion range (Pattaras, Smith, Landman, & Moore, 2001) Th e most common suturing approach is the conventional technique, which consists of using a curved needle and two needle drivers to perform the task. According to Adams et al., the time for each suturing placement through the conventional method averages 151 24 seconds and each knot tying time of conventional tec hnique is on average 19770 seconds (Adams, Schulam, Moore, Partin, & Kavoussi, 1995) If we consider that a surgeon has to knot six times on average, the duration of the operation increases considerably due to suturing. Although suturing devices for minimally invasive

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5 surgery are commercially available and currently being used, surgeons still indicate the nee d for better devices that can facilitate the suturing and knot tying procedures during minimally invasive surgeries. The main limitations for designing devices for this type of surgery are the limited space and motion range, which greatly constraint the di mensions and mechanisms of the device. 1.2 Thesis Objectives and Contributions The proposed research aims to address the main laparoscopic suturing challenge s and curren t literature limitations in the market The main goal of this resear ch is to investigate, design, and develop a new medical device system for facilitating suturing and knot tying procedures during minimally invasive surgery. The device will also enable the use of any type of suture on the needle. The major objectives of this thesis are: 1. To investigate and design a new suturing device to minimize the suturing risks and difficulties during minimally invasive surgery. This device aims to decrease the suturing operating time while being intuitive for surgeons to use. 2. To implement a phys ical prototype of the design to analyze and test the effectiveness of the device. This research focuses on the suturing and knot tying procedures during hysterectomies, which is the second most common surgery among women in the U.S. according to the U.S. D epartment of Health & Human Services. However, the proposed research can be applied to any minimally invasive surgical procedure that requires

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6 uterus and sometimes the ova ries and fallopian tubes. Suturing and knot tying is required after the uterus is removed from the patient. This new instrument aims to benefit both patients and surgeons. For surgeons, the new device aims to minimize the suturing difficulties encountere d during minimally invasive surgery. This is expected to help surgeons in performing suturing faster and safer. For patients, the proposed device will reduce the surgery time thus reducing the time under general anesthesia. At the same time, the proposed s uturing device contributes d to improved health care. 1.3 Thesis Outline Chapter 2 discusses current research work and available devices for suturing and knot tying during minimally invasive surgery. Chapter 3 examines the conventional suturing device and knot tying technique commonly used in minimally invasive surgery through a human factors approach. This examination provides recommendations for the device design. Chapter 4 describes a new surgical suturing device and its design stages. Each design stage is introduced to understand the logic behind the new instrument. Chapter 5 provides a summary of the research methodologies presented and future research work.

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7 Chapter 2 Literature Review This chapter provides the background of current research work in the area and introduces suturing devices currently used in minimally invasive surgery. Current designs are analyzed and their limitations identified. 2. 1 Conventional Laparoscopic Suturing and Knot Tying Process The conventional suturing technique has been performed for many years and it is still the most common suturing technique used by surgeons even though it has many difficulties. It is performed by using a curved needle and two elongate d needle drivers. The curved needle and needle drivers are inserted through the laparoscopic ports and suturing placement is performed manually inside body Many types of needles exist that are specifically designed for conventional laparoscopic suturing. In previous years, straight needles were used for laparoscopic suturing as they were easier to introduce into the abdominal cavity; however, it was difficult to control them while suturing (Sanfilippo & Solnik) Curved n eedles are currently used for suturing in minimally invasive surgery, as shown in Figure 2.1. They have become very popular but need to be handled using elongated laparoscopic needle drivers and Maryland Grasper s as shown in Figures 2.2 and 2.3, respectively. For this reason, the first problem with curved needles is that hands on experiences using these instruments are needed. The second problem is that curved

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8 needles can be difficult to insert in the correct loc ation as the abdominal wall prevents fre e movement of the needle driver (Sanfilippo & Solnik) Fig ure 2.1: C urved needle with surgical suture [photograph]. Retrieved February 10, 2010 from www.wikisurgery.com Fig ure 2.2: Laparoscopic needle driver [photograph]. Retrieved February 10, 2010 from www.kenzmedico.co.jp Fig ure 2.3: Maryland g rasper [photograph]. Retrieved February 10, 2010 from www.stryker.com

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9 To facilitate the conventional suturing and knot tying technique, various types of suturing and knot tying approaches have been introduced in previous years. The oldest techni que is in tra corporeal suturing and extra corporeal knot tying technique as shown in Figure 2.4 (Liu, 1993) Extra corporeal knot tying is a method to avoid the difficult and time consuming skill of intra corporeal knot tying Two elongated laparoscopic needle drivers and a curved needle are used to suture On the other hand, knot is tied outside the body and then the loop is pushed into the operating area by a kn ot pusher as shown in Figure 2.5 This technique also requires high level skills. Figure 2.4: Extra corporeal knot tying technique (Liu, 1993) Figure 2.5: Knot pusher [photograph]. Retrieved February 15, 2010 from www.calicutsurgicals.com

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10 There are two categories of knot tying techniques that are used in extra corporeal tying : half hitches and compound sl iding knots. As shown Figure 2.6 the half hitches knot is the sim plest of all sliding knots formed and the basis for a multitude of other knot s used. The half hitches technique is described in the medical dictionary as one straight strand with the other thrown over, back over itself, under the original strand and back through the loop created by the earlier steps. It is the basis for square, granny and surgeon's knots, depending on how the hitches are thrown ("Half hitches technique", 2010) Figure 2.6: Half hitches knot techniques (Khattab, 2008) The compound sliding knots technique is shown in Figure 2. 7 This knot technique has more than one turn of the wrapping limb around the post (i.e. any sliding knot other than a half hit ch). It can be app l ied in situation s where the suture slides smoothly and freely through the tissue and anchoring device. The a dvantage of the

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11 compound sliding knots is that the knots can be made to slide down the post limb without unraveling or jamming p rematurely. Theoretical disadvantages include abrasion of suture against the anchor eyelet and suture cutting through tissue as it slides (Lo, 2008) (Gunderson, 1987) (De Beer, van Rooyen, & Boezaart, 1998) (Delimar, 1996) (Fleega & Sokkar, 1999) (Holmlund, 1974) (Hughes, Hagan, Fisher, Hold, & Frostick, 2001) (Ilahi, Younas, Alexander, & Noble, 2004) Figure 2.7 : Compound sliding knots (Khattab, 2008) Due to the difficulties to operate the intra corporeal suturing and extra corporeal knot tying technique, another tech nique called intra corporeal suturing and intra corporeal knot tying technique was introduced as shown in Figure 2.8 (Topel, 1996) In this technique, a curved needle with suture and two elongated laparoscopic needle drivers are used for suturing a nd knot tyi ng. As the operation is performed inside the body, this technique requires high level skills to manipulate the curved needle and to pass the needle from the first needle driver to the next. Another difficulty of this technique is the limited wor king space available to use the knot tying instruments inside the body

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12 Figure 2.8 : Intra corporeal suturing and intra corporeal knot tying technique (Topel, 1996) 2.2 Commercially Available Suturing Devices M any laparoscopic suturing systems have been developed in recent years (Kennedy, 1992) (Grace, P, & D., 1 992.) However, most of them are not always successful and sometimes cause new and different problems such as loss of pneumoperitoneum, excess tension on the tissue that is being re approximated and s uture breakage during placement (Adams, et al., 1995) The most commonly used suturing devices are by Covidien and Capio by Boston Scientific, which are described in the following sections. 2.2.1 10 mm Suturing Device As shown in Figure 2.9, 10 mm ("Endostitch 10 mm suturing", 2008) serviced by Covidien is one of the devices currently used for laparoscopic suturing. single use suturing device has two jaws and consists of four main parts: a

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13 handle, a toggle lever, a needle holder secured inside the jaws and a needle. The device can be operated through the handle and the toggle lever. Also, the suture is secured in the middle of the needle so that the suture can pass through the tissue. After the needle holder is loaded with the n eedle and suture, the needle is passed from one jaw to the other by closing the handles and flipping the toggle lever Rotating the toggle lever and releasing the handle enables the needle to stay on the opposite jaw. When this is complete, t he needle is ready for the next maneuver. This device can also be used to tie knots as shown in Figure 2.10. [photograph]. Retrieved February 13, 2010 from www.autosuture.com Adams et al. compared the automated suturing using the with conventional techniques in 1995 Results showed that the allowed placing individual sutures faster, reducing the required time by two thirds The data demonstrate d that the significantly decreased times for suturing placement and knot tying compared to the conventional approach For suturing placement time the Endo averaged 4327 seconds whereas the conventional method averaged 15124 seconds. Moreover, while Endo St knot tying was performed o n an average of 7450 seconds, conventional technique averaged 19770 seconds. The also automatically reload s the needle for each maneuver.

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14 Figure 2.10: Knot tying technique with (Huhn, 2004) 2.2.2 Capio Open Access and Standard Suture Capturing Device Another instrument used for suture placing is Capio The device is designed for general suturing applications during open and endoscopic surgery to assist in the placement of suture at the operative site ("Capio open access", 2010) As shown in Figure 2.11, the device has six main parts, (1) needle carrier, (2) head, (3) s uture, (4) elongate body, (5) needle driver b u tton (6) alignment indicator ("Capio open access", 2010)

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15 Figure 2.11: Capio suture capturing device [drawing]. Retrieved February 13, 2010 from www.bostonscientific.com The pr inciple of operation is suture placing with a needle and thread As shown in Figure 2.12, t he needle is placed at the tip of the device. With the push of the button, the needle is transported t hrough the tissue carrying a th read and is caught by t he needle catcher. The user removes the needle from the needle catcher and reloads the needle at the tip of the device.

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16 Figure 2.12: Partial schematic perspective views of distal portio n of Capio [drawing ]. Retrieved February 13, 2010 from www.bostonscientific.com Using this device is more effective and less painful for surgeons than a method where the surgeon has to remove the device from the surgical site and reload. This is particularly useful when the surgical site is located very deep inside the body and is difficult to reach. For instance, Capio is used for trans vaginal repair of para vaginal defect operation as the surgical site is located deep inside the body and is not easily accessible as shown in Figure 2.13 (Nguyen & Bhatia, 1999) Needle catcher

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17 Figure 2.13: Transvaginal and paravaginal defect repair using the Capio (Nguyen & Bhatia, 1999)

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18 Chapter 3 Case Study on Conventional Suturing Process The conventional suturing process, which is commonly used by surgeons during minimally invasive surgery, is analyzed in this chapter. Based on a case study on human factors analysis, the limitations of the conventional suturing process are identified and r ecommendations are proposed for a new device design. 3.1 Human Factors Engineering Human Factors Engineering (HFE) is the science of designing or improving products, processes, and work environments by considering human capabilities and limitations. HFE can be applied to any process that involves a human interface ranging from the improvement of a system design, performance and reliability to user satisfaction. It can also be applied to procedures to reduce operational errors, operator stress, user fatigue and product liability. HFE helps improve human capabilities while decreasing possible risks that can occur during the use of the device. It also enables a better understand ing of the operating process of a medical device to reduce device training and to increase the safe use of the device

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19 3.2 Introduction to Case Study The conventional suturing and knot tying process was selected for the case study because it is still the most common suturing technique used by surgeons. Task Analysis and Failure Mode and Effect Analysis (FMEA) are used to identify the difficulties faced by surgeons. I n this study, data for the user needs came from observations and interviews. Information about the features of the user environment and the device functions were collected through on site observation of the users, the surgeon and nurses were observed informally in operati ng rooms at the time of surgery for several days. Field n otes were taken during the se operations to identify the features of the user environment and the requirements for the suturing device. With this approach, the task s carried out by the device were analyzed It was observed that the device is to be used under direct visualization only during open or endoscopic surgeries The device is to be of single use only and disposable so that it does not require any maintenance The device is to be made of biocompatible materials and its main function is to assist in the placement of suture material in tissues. In addition, the length of the device should be larger than 280 mm and its diameter should be less than 12 mm due to the size of the maximum laparoscopic port 3.3 Laparoscopic Instruments U sed for Suturing and Knot Tying The extra corporeal knot tying approach uses many devices for the suturing and knot tyi ng process, a s shown in Figure 3.1 Curved needles of d ifferent size s are used for the suturing operation and are manipulated with a laparoscopic needle driver and a cut the surgical suture out of the body after the suturing operation is finished. Small

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20 surgical forceps are used to retain the su ture outside of the body. After knot tying is performed by using extra corporeal knot tying approach, the loop is pushed into the body using a knot pusher. Finally, laparoscopic scissors are used to cut the suture after the knot is tied inside the body. Th ese seven devices are used only for one loop. (a).Needle surgical suture (b) Needle Driver (c) Surgical forceps (d) Maryland needle driver (e) Surgical scissors (f) Knot pusher (g). Endo Shears Laparoscopic scissor Figure 3.1: Instruments used for conventional laparoscopic suturing and knot tying

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21 3.4 Task Analysis Task analysis is the analysis of how a task is accomplished. A task could be a process or the use of a device. Task analysis is used for several different pur poses including personnel training, process understanding and device or process design. Jonassen describes task analysis as "a process of analyzing and articulating the kind of learning that you expect the learners to know how to perform" (Jonassen, Tessmer, & Hannum, 1999 ) Table 3.1 shows the task analysis to understand the steps of the suturing and knot tying procedure using the extr a corporeal knot tying approach These steps are performed for one loop and must be repeated for each additional loop which shows the complexity of the suturing and knot tying process. Each step in the table represents actions performed in the suturing and knot tying process and how the device responded after those actions. Task analysis was also used to observe if there wa s any problem with the current processes and devices. For instance, although there was no observed problem for step 1 in the table, there was an observed problem for step 5. Once the user inserts the needle driver with needle suture into the body through the biggest inc ision, the needle sometimes gets trapped by the port. This observation helped to see the current issue s with the conventional suturing process Therefore, perform ing the task analysis was very important in this research to anticipate potential problem s when designing the proposed device

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22 Table 3.1 : Task analysis for conventional suturing process Step User Action Device Response Observed Problem 1 Pick up the needle suture None None 2 Unpack the needle suture None None 3 Hold the suture from 2 cm with the needle driver The needle driver grasps the suture None 4 Hold ith a small surgical forceps It stays outside the body. The surgical forceps grasp the suture None 5 Insert the needle driver with needle suture into the body through the big gest incision The needle driver goes into the body with the needle and suture The needle sometimes gets trapped by the port. 6 Insert the Maryland n eedle grasper into the body through one of the small incision s It goes into the body None 7 Hold the needle with the Maryland needle grasper Maryland needle grasper seizes the needle The needle is not caught in the correct position on the first time 8 Pass the needle to the needle driver The needle driver grabs the needle The needle cannot be caught by the needle driver on the first time. The needle is in the wrong position so it has to be corrected to the right position. Sometimes it takes time. 9 Hold the tissue with the Maryland needle grasper Maryland needle grasper catches the tissue None

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23 Table 3.1: (Continued) 10 Place the needle on the t issue with the needle driver The needle goes through the tissue The needle cannot stay on the head of needle driver in the correct position. It has to be caught with the Maryland needle grasper first and then it is grasped by the needle driver. This is repeated until the needle is grasped in the correct position. 11 Release the tissue and Maryland nee dle grasper is free now None None 12 Hold the needle with the Maryland needle grasper Maryland needle grasper seizes the needle The needle is not caught in the correct position on the first time 13 Pull the needle away from the tissue The needle goes out Hand s on experiences are needed 14 Hold the needle with the needle driver Needle driver grasps the needle The needle cannot be caught by the needle driver on the first time. The needle stays in the wrong position so it has to be corrected to the right position. Sometimes it takes time. 15 Hold the other tissue with the Maryland needle grasper Maryland needle grasper catches the tissue None

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24 Table 3.1: (Continued) 16 Place the needle on the t issue with the needle driver The needle goes through the tissue The needle cannot stay on the head of needle driver in the correct position. It has to be caught with the Maryland needle grasper first and then it is grasped with the needle driver. This is repeated until the needle is grasped in the correct position. 17 Release the tissue and Maryland needle grasper is free now None None 18 Hold the needle with Maryland needle grasper Maryland needle grasper grasps the needle The needle is not caught the correct position at the first time 19 Hold the suture from 2 cm with the needle driver The needle driver grasps the suture None 20 T ake out the Maryland needle grasper from inside the body None None 21 Take out the needle driver and needle from inside the body The needle driver and needle go out of the body The needle sometimes gets trapped by the port. 22 Cut the suture with a scissor The needle and suture are separated None 23 Put the need le and the needle driver on the table None None 24 Take the knot pusher None None 25 Hold the suture with one hand None None 26 Replace the suture into the knot pusher None None 27 Take the small surgical for ceps from end of suture None None 28 Hold the suture with the small surgical forceps on th e same side with knot pusher None None

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25 Table 3.1: (Continued) 29 While an assistant is holding the small surgical forcep s hold the suture with the left hand and hold the knot pusher with the right hand at the same time None A second person is needed to do it. 30 Tie a knot out side of the body None Hands on experience is needed. 31 Push the loop in side the body by using the knot pusher Knots go in side the body It should go inside the body smoothly. Otherwise it breaks 32 Make sure the loop is place d in the correct direction None None 33 Take out the knot pusher from inside the body None None 34 Cut the suture inside the body with Endo Shears Laparoscopic s cissor s Knots stay inside None 35 Repeat steps 1 33 about seven times None None 3.5 Failure Mode and Effect Analysis (FMEA) Failure mode and effect analysis is a procedure us ed in the product development and product design stages for avoiding any possible failure before the process or device design are completed. It helps people to define the potential failure modes. FMEA is used to identify potential failure modes, determine their effect on the operation of the product, and identify actions t o mitigate the failures. methodology for analyzing potential reliability problems early in the development cycle (Ramasamy, 2005) Table 3.2 shows the Failure Mode and Effect Analysis to identify the current and potential failures during the conventional suturing process The main objective of performing such analysis was to find the Risk Priority Number (RPN) score which is used to prioritize potential failures that require additional quality planning or action. The

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26 RPN is the mathematical product of the severity ranking of each effect of failure and the probability ranking of each potential cause of failure to the user and patient. As a common industry standard scale, t he range of values for severity and probability ranking are from 1 to 10 as shown in Table s 3.3 and 3.4 respectively. Based on these values, the RPN scores for each function were obtained using Eq. 3.1 as follows (Crow, 2020) : RPN = (Se verity ranking ) x (Probability ranking ) (3.1) The Failure Mode and Effect Analysis enables the designers to focus more on eliminating the high scored failures. For instance, one of the potential failures with high score in Table 3.2 is with a RPN score of 72 This happens because of the difficult y to maneuver the two needle driver s and results in a long time to catch the tissue by the surgeons. This failure was considered in the design process of the proposed device Table 3.2: Fa ilure mode and effect a nalysis for conventional suturing process Item/Part/ Function Potential Failure Mode(s) (what might happen) Potential Cause(s) of Failure (why it happens) Effects Sev Prob. R PN H olding the curved needle with needle drivers The needle cannot be held with the needle driver Difficult to hold the needle because of the needle shape L ong operation time 8 4 32 The user does not have experience Same as above 8 3 24 A wrong needle driver is used Same as above 8 2 16 The needle falls down Difficult to hold the needle because of the needle shape The needle has to be changed 5 4 20 The user does not have experience L ong/ expen sive oper. 9 3 27

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27 Table 3.2: (Continued) A wrong needle driver is used Same as above 8 2 16 Inserting the curved needle into the body The needle cannot be inserted into the body The port is too small The operation cannot be performed 10 3 30 The needle is held in the wrong position Dangerous maneuver 10 7 70 The needle is too big The operation cannot be performed 10 6 60 Passing the needle from a needle drive r to another needle driver The needle falls loose inside the body Difficult to hold the needle because of the needle shape The user can damage the organs 10 4 40 The user does not have experience Same as above 10 3 30 The working area is not visible Same as above 10 9 90 Catching the tissue with the curved needle by using needle drives The tissue cannot be caught by using the needle drivers The working area is not visible The user can damage the organs 10 9 90 There is too much blood in the working area Same as above 10 8 80 Difficult to maneuver the two needle driver s L ong operation time 8 9 72 The user does not have experience The user can damage the organs 10 3 30 Performing the knot tying out of the body. Loops are too loose The user does not have experience L ong and expensive operation 9 3 27

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28 Table 3.3: Severity ranking c riteria (Villacourt, 1992) Rank Description 1 2 Failure is of such minor nature that the customer (internal or external) will probably not detect the failure. 3 5 Failure will result in slight customer annoyance and/or slight deterioration of part or system performance. 6 7 Failure will result in customer dissatisfaction and annoyance and/or deterioration of part or system performance. 8 9 Failure will result in high degree of customer dissatisfaction and cause non functionality of system. 10 Failure will result in major customer dissatisfaction and cause non system operation or non compliance with government regulations Table 3.4: Probability ranking c riteria (Villacourt, 1992) Rank Description 1 An unlikely probability of occurrence 2 3 A remote probability of occurrence 4 6 An occasional probability of occurrence 7 9 A moderate probability of occurrence 10 A high probability of occurrence

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29 Chapter 4 Design Process of the Proposed Laparoscopic Suturing Device In this chapter, the design process for a new medical device for laparoscopic suturing is described through the stages of analysis, synthesis, and evaluation. Various design concepts are presented and discussed followed by concept selecti on and testing. 4.1 Definition of Medical Device and Design Process A brief description of the medical device can be useful to understand the design process of a medical device. According to the Food and Drug Administration (FDA) a medical device is an instrument, apparatus, implement, machine, contrivance, implant, in vitro reagent, or other similar or related article, including a component part, or accessory which is: recognized in the official National Formulary, or the United States Pharmacopoeia, o r any supplement to them, intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease, in man or other animals, or intended to affect the structure or any function of the body of man or other animals, and which does not achieve any of its primary intended purposes through chemical action within or on the body of man or other animals and which is not

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30 dependent upon bein g metabolized for the achievement of any of its primary intended purposes (Food and drug administration 2010) Also, the Food and Drug Administration has categorized medical devices into three classifications, Class 1, Class 2 and Class 3. Classification is risk based so t he lowest risk devices fall into Class 1 while Class 3 includes high risk medical devices such as artificial heart s T he proposed device can be considered a Class II device because it needs special controls such as endotoxin testing, sterilization validation, design specifications, labeling requirements, biocompatibility testing, and clinical testing. The medical device design process includes the steps that are helpful in the design of a new product. The Analysis Synthesis Evaluation model has mostly been use d in design activities. A design process involves a considerable amount of analysis, investigation of basic physical processes, experimental verification and difficult decisions. The d esign process is a cyclical process as each step in the process follows and leads to one another as shown in Figure 4.1. Figure 4.1: Product development p rocess (Cetin, 2004)

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31 T he following sections describe the analysis synthesis evaluation model used for developing the proposed laparoscopic suturing device as shown in Figure 4.2 Results are also presented and discussed. Figure 4.2 : Product development p rocess for the proposed device 4.2 Analysis Stage In the analysis stage, t he problem is defined and also client and design requirements are created As shown in Figure 4.3 the a nalysis stage consists of two sub steps : analysis of the problem and product design specification. Figure 4.3: S ub steps of the a nalysis stage Analysis Stage Analysis of the Problem Product Design Specification Analysis of the Problem Product Design Specification Analysis Stage Synthesis Stage Evaluation Stage Developing Alternatives Solutions Modeling and Engineering Analysis Choosing a Solution Prototyping and Evaluating Product Development Process

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32 4.2.1 Analysis of the Problem In order to solve a problem, it has to be clearly analyzed and defined. There are methods to help und erstand the problem and they are usually used in the analysis stage of the medical device design. As the first meth od, a literature search was conducted. Important and useful info rmation about the field was obtained through this method by analyzing and eva luating the published reports, patent records and published books. The second method for un derstanding the problem was observational analysis. On site observations of the surgical procedure were performed at a local hospital to identify the needs and diffi culties of the users use of current device s and conventional techniques were observed. Observations were performed at Tampa General Hospital every other month during one year. Six cases were randomly s elected and observ ed. Informal field notes were taken throughout these observations. User interviewing was the third method to be used to understand the problem. In this research, there was a constant collaboration with a surgeon operating minima lly invasive surgery This collaboration provided important and useful information on the problem and serve d as reference for design planning. Interviews were done during and after each operation observed. During the inter views, the researcher took informal notes. Another me thod used in this stage was benchmarking. This method help s to understand the capabilities of the devices currently available in the market. Three suturing approaches were analyzed to identify advantages and drawbacks: Capio and conventiona l suturing process. The patent documents were used to get

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33 information about other devices that are in the patent process but not currently commercialized. Finally, task analysis was performed to capture the structure of tasks underlying t he activity. This stage was used after the interview and observation methods. Through this analysis, the operating sequence was understood, and problems were defined. 4.2.2 Product Design Specifications Once the problem is defined, the functions, purpose and characterist ics of the new instrument are defined The product design specification do, how it will do it and how reliable it will be. To be effective, it must be as precise as possible (Fries, 2001) Requirements that are most important for the solution of the problem were defined and separated into two main categories: client requirements and design requirements. Client requirements were determined as: The new tool should be easy to use, ergonomic and be able to be operated by one hand body The new tool should be able to be used on all types of surgeries th at require suturing and knot tying On the other hand, the design requirements were determined as follow: Performance requirements: Must be portable and require minimal hands on experience by the surgeons. Safety: Must not harm patient in any way

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34 Accuracy and Reliability: Must be able to perform suturing and knot tying accurately and reliably Life in Service: Must be disposable with no need for maintenance Operating Environment: This device will be used in a surgery room environment and will be in conta ct with tissue, organs, blood and other liquids. natural holding Size: The device must fit into a 12 mm endoscopic port and its length must be at least 280 mm to reach the oper ating area Weight: The entire device should not weigh more than 1 pound Shelf Life: The shelf life will be five years stored at room temperature in a dry location. Materials: There are no restrictions on materials. Detailed product design specifications are shown in Table 4.1 below.

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35 T able 4.1: Product design s pecifications Client requirements Function Requirements Utilization The new device should be used on all types of laparoscopic surgery Operating It should be operated by one hand Ergonomic It should be easy to hold and maneuver Suturing/Knot tying Knot tying should be body Design requirements Value Needle and thread Should be able to operate in two directions, left and right Length of the shaft > 280 mm Outer diameter <12 mm Weight <1 pound Life in service Disposable/ no need for maintenance Safety Must not harm the patient in any way Accuracy/ Reliability Must be accurate and reliable

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36 4.3 Synthesis Stage In the synthesis stage, all possible solutions are developed and the best ones are combined. Then, the best solution is selected based on the customer and design requirements. Figure 4.4 shows the sub steps of the synthesis stage Figure 4.4: Sub steps of the s ynthesis stage 4.3.1 Developing Alternative Solutions Design concepts were generated based on the client and design requirements for the new device. Current devices and mechanisms used for suturing were investigated to create alternative solutions that address existing drawbacks. The similar and possible devi ces were brainstormed and analyzed. The design concepts were discussed and compared to create alternatives. s can be the starting point to g ui de the brainstorming process. Critical functions of the new device were determined and evaluated. Two functions were determined to be critical such as suturing placement and needle movement in both directions during suturing. The most important part for the new device was the suturing mechanism followed by the ergonomic handle. According to the research results, Synthesis Stage Developing Alternatives Solutions Choosing a Solution

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37 hand sketches for possible mechanisms were prepared and discussed. Solidworks was used as 3D CAD software to simulate possible alte rnatives as shown in Figures 4.5 4.9 In this stage, it was very important to cover every possible solution since the following phases require discussions with the surgeon. Figure 4.5 : Alternative design 1 Figure 4.6 : Alternative design 2

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38 Figure 4.7 : Alternative design 3 Figure 4.8 : Alternative design 4 Figure 4.9 : Alternative design 5 4.3.2 Choosing a Solution In this stage, the data obtain ed in the analysis stage was transformed in to the synthesis stage in order to select new d evice concepts. The first method was synectics. According to Jones, t and the nervous system towards the exploration and transformation of design

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39 (Jones, 1992) ruled out, and the group members attempt to built, combine and develop ideas towards a creative solution to set t (Cross, 2000) Critical functions of the new instrument were identified and evaluated according to the client requirements and design specifications. Five main factors were identi fied including utilization, operating, ergonomic, operating direction and suturing knot tying. For each of these functions several different alternatives w ere brainstormed. Then, these alternatives were evaluated and selected based on external criteria, internal criteria and social factors as shown Figure 4.10 Figure 4.10 : Design decision factors (Ulrich & Krishnan, January 2001) The best alternative for each function was determined using Pugh charts as shown in Table 4.2. To produce co mplete tool concepts, the highest ranking and most compatible forms were chosen for each of the five functions and integrated together. From these complete concepts, a system Pugh chart was used to select the best design. As shown in Table 4.2, a weight wa s assigned to each function indicating the importance of

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4 0 each criterion. Then, for each alternative, a value of 1 or 1 was assigned based on wh ether the alt ernative meets or does not meet the user needs, respectively. After each alternative was rated the alternative that has highest score was selected as the best alternative It can be observed that alternative 5 has the highest rating compared to the other alternatives and consequently, it was selected a s the best design Table 4.2 : Pugh c hart Alternatives Weight Altern.1 Altern.2 Altern.3 Altern.4 Altern.5 Criteria Utilization 5 1 1 1 1 1 Operating 7 1 1 1 1 1 Ergonomic 9 1 1 1 1 1 Knot Tying 7 1 1 1 1 1 Oper. Direction 10 1 1 1 1 1 Score 14 38 4 6 28 4.4 Evaluation Stage In the evaluation stage, the chose n solution is modeled analyzed and further improved prior to the fabrication of the physical prototype for testing As shown in Figure 4.11, this stage has two sub steps to evaluate the prototype : modeling and engineering analysis and prototyping and evaluating

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41 Figure 4.1 1: Sub steps of the e valuation s tage 4.4.1 Modeling and Engineering Analysis In this research, SolidWorks 2009 CAD software was used to make detailed 3D solid model s of the device. Prior to prototyping, the design was tested using finite element analysis (FEA) with SolidWorks SimulationXpress. This identifies potential design problems in advance to make the corresponding design modifications. Figure 4.12 shows the selected detailed design concept from Section 4.3.2. It consists of eight main parts: handle, trigger, arm, needle car rier, needle holder needle, sheath and flexible wire The sheath of the proposed device is 11.5 mm in diameter and can be used on a 12 mm port. At the tip of the device, the t wo arms can be closed by sliding the sheath from back to front Once the sheath is retracted, the s uturing arms return to their original positions The suture is secured at the center of the needle, which is sharp on both ends to allow passage through the tissue in both directions. An advantage of the design is that the needle can use a ny type of suture while current devices require the use of a proprietary suture The trigger activates the needle carrier from one side of the arm to the other while the toggle lever changes the direction of the needle between the arms, as shown in Figure 4.13 A needle ho lder secures the needle inside the arms while also allowing the needle to be transferred to the opposite arm After the needle has been Evaluation Stage Modeling and Engineering Analysis Prototyping and Evaluating

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42 transferred the stitch is then pulled through the tissue. At this point, the needle is ready for the next maneuver. Figure 4.12 : 3D CAD model of the proposed device Shaft Flexible wire Trigger Toggle lever Sheath Handle Arms

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43 Figu re 4.13 : Mechanism for needle transporting of the proposed device Suturing and knot tying operation procedures for the proposed device is outlined as below. The procedure is meant to be quick and simple for the surgeons, as well as being safe for the patients. 1. Load the needle and suture to the needle h older 2. Rotate the sheath and push it to the front 3. Insert the tool inside the body 4. Retract the sheath to arms 5. Rotate the toggle lever to the same side with needle Needle carrier Needle Needle holder

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44 6. Push the trigger 7. The needle with the suture goes through the tissue and stays on the opposite arm 8. The device is ready for next maneuver The proposed device can also be used to tie square knots, a su variety of knot tying. The design concept aims to enable surgeons to perform suturing and knot tying procedures through extra corporeal or intra corporeal knot tying approaches. In order to analyze the new device, materials have to be defined. Table 4.3 shows the different components for the proposed device with their corresponding selected material a nd important dimensions. Table 4.3: Types of material Part Material Type Important Dimensions Handle Thermoplastic Width: 140 mm Depth: 50 mm Height: 140 mm Trigger Thermoplastic Width: 10 mm Depth: 3 mm Height: 55 mm Outside shaft Thermoplastic Diameter: 11.5 mm Length: 280 mm Sheath Thermoplastic Diameter: 9 mm Length: 320 mm Main plunger Titanium Diameter: 5.5 mm Length: 285 mm

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45 Table 4.3: (continued) Toggle Thermoplastic Diameter: 30 mm Thickness: 5 mm Small plunger T itanium Width: 1.5 mm Depth: 1.5 mm Height: 30 mm Arms Polycarbonate Width: 15 mm Depth: 4 mm Height: 50 mm Flexible wire Titanium Diameter: 0.60 mm Length: 40 mm Needle Stainless steel Diameter: 0.70 1.2 mm Length: 4 mm Needle carrier Stainless steel Diameter: 1.2 mm Length: 10 mm Needle holder Silicon rubber Diameter: 1.55 mm Thickness: 1.2 mm Three parts were the most important parts for the proposed device. The first part is the tip of the device where the arms are located as shown in Figure 4.14 The arms stay inside the sheath and then move to the open position once the sheath is retracted. This requires a flexible and strong material such as polycarbonate (PC). Polycarbonate is a highly hard plastic and it is traded by Lexan . This plastic is very useful in designing medical devices as it provides high impact strength, crystal clear transparency, abrasion resistance, and dimensional stability. It can be found in the market in different colors such as black, gray, and optical clear and in differ ent shapes such as rod, plate and sheet. Yield strength of polycarbonate is 69.7 MPa and Poi s son s ratio is 0.37. Polycarbonate is

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46 a thermoplastic and can be injection molded for mass production, which is the ideal method for potential manufacturing of thi s part. Figure 4.14 : Arms at the tip of the proposed device To perform the finite element analysis for the arms, 1 lb force was applied to the arms. Figure 4.15 shows the stress distribution on the arms. As shown in the figure, yield strength of the selected material is 69.7 MPa On the other hand, maximum stress for the critical part is 26.47 Mpa according to the applied force. The blue area in the picture is th e area with the least stress of the part. Red areas indicate the most critical regions for the parts and show the maximum stress at 26.47 MPa. According to the result of the stress distribution test, the arms can be stored inside the sheath, which is 11.5 mm in diameter, without any permanent deformation because the maximum stress for the part is smaller than the yield strength of the selected material.

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47 Figure 4.15 : FEA results of stress distribution in the arms of the device F actor of safety [FOS] for this part is: 2.63238. Parts with [FOS] higher than 1 are considered to be safe. This value can be increased or decreased by choosing different types of materials. Figure 4.16 shows displacement distribution in the arms and deform ed shape of the arms. As shown in the figure, maximum displacement distribution is 1.636 mm.

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48 Figure 4.16 : Displacement distribution in the arms and deformed shape of the arms O ther critical part s of the proposed device are the flexible wire small plunger and main plunger as shown in Figures 4.17 4.19 respectively. The flexible wire is located inside the arms and sha ft and is used to push the needle carrier s It must be flexible because it moves through two curves inside the jaws to apply m ore force to push the needle carrier s

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49 Figure 4.17 : The flexible wire to control the needle carriers Figure 4.18 : Small plunger Figure 4.19 : Main plunger Flexible wire Cavity Small part of the main plunger

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50 The small plungers and main plunger are also located inside the shaft and the flexible wire is connected to a small plunger as shown in Figure 4.20 There are two small plungers to control the arms at the tip of the device. As the user rotates the toggle lever, the small part of the main plunger goes into the cavity of one of the small plungers as shown in Figure 4.21 This engages the main plunger with the small plunger and user rotates the togg le lever in the opposite direction, the main plunger engages with the other arm to move the corresponding needle carrier. Therefore, the toggle lever is used to alternate control between the two arms and thus provide the motion of the needle in both direct ions. Figure 4.20 : Relationship between the main plunger and small plunger Main plunger Small plunger Small plunger Connection with small plunger and flexible wire

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51 Figure 4.21 : Detailed view of the mechanism for changing the needle direction The main plunger and small plungers must be strong because forces will be applied here to make the needle go through the tissue. For this reason titanium was selected as a proposed material. Titanium has significant benefits as it i s flexible, light weight, easily worked biocompatible and strong Titanium is not as dense as stainless steel but yields double the strength as stainless steel. Also, the ultimate tensile strength of titanium is approximately 25% higher. In addition to these features, titanium has outstanding corrosion resistance. All these features allow a wide range of successful applications of tit anium that result in high levels of reliable performance in a broad range of major industries from medicine and surgery to aerospace and automotive. For example, in the field of medicine, titanium is perfect for implantation in the human body, such as join t replacements. To perform the finite element analysis for the small plunger and main plunger, the force that would be applied had to be defined. From previous research, it was determined that a minimum puncture force of 4.61 N is required to puncture the toughest tissue of the stomach with a laparoscopic suturing needle (Cronin, Frecker, & Mathew, 2007) There Cavity

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52 is no study that defines puncture force for the uterus, so 4.61 N (F was established as the minimum puncture force for the finite element analysis. The force at the tip of the device needed to generate at least 4.61 N was investigated. To define that force Eq. 4.1 was used as follows: ln ( F (4.1) Where F2 is the force needed to get minimum puncture force and F1 is minimum puncture force. After applying the force t o the small plunger, Figure 4.22 shows the s tress distribution on the small plunger and deformed shape of the part. As shown in the figure, the yield strength of the selected material, which is titanium, is 1,034.21 MPa and is 0.33. The maximum stress for the critical portion is 11.21 Mpa according to the applied force. The lowest factor of safety [FOS] for this part is 92.2098, which is good for safety design. Also, Figure 4. 23 demonstrates that there is only 0.00005129 mm displacement distribution for the most critical part of the small plunger according to the applied force of 6N.

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53 Figure 4.22 : S tress distribution on the small plunger and deformed shape of the part Figu re 4.23 : Displacement distribution on the arms of the small plunger

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54 Similarly, finite element analysis was performed on the main plunger and the resul ts are shown in Figure 4.24 A force of 6N was applied to test the part and results show that the l owest factor of safety for the main plunger [FOS] is 68.2331 which is a high value indicating that the part can be used safely for this operation. Likewise, Figure 4.25 shows there is only a 0.00007146 mm displacement distribution for the most critical part of the main plunger according to the applied force of 6N. Figure 4.24 : S tress distribution on the main plunger and deformed shape of the part

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55 Figure 4.25 : Displacement distribution on the arms of the small plunger S tainless steel was used on the needle and needle carriers as shown in Figure 4.26 Stainless steel is a low carbon steel that contains at least 10% of chromium in its weigh. Th e chromium gives t he steel stainless and corrosion resisting features. Although there are more than 60 different types of stainless steel in the market, the main group is divided into five classes: austenitic, ferritic, martensitic, p recipitation hardening martensitic, and d uplex Each is identified by the alloying elements which affect their microstructure and for which each is named. There are several benefits of stainless steel such as corrosion resistance, fire and heat resistance and hygiene ("Stainless steel", 2010)

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56 Figure 4.26 : Needle and needle carrier Silicon rubber was another material used in the new instrument. It was used for the needle holder as shown in Figure 4.27 The needle holder keeps the needle while also releasing it when transported by the needle carrier. A type of plastic with a thermoset feature is silicon. Silicon is highly stable and has a strong resistance to heat. It is also biocompatible. It is cured by two catalyst systems: peroxide and platinum cure. Figure 4.27 : Needle holder Needle Needle carrier Needle holder Space Arm 1mm 1.55mm 0.7mm 1.2mm

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57 According to the t est results shown in Figure 4.28 the yield strength of the selected material which is silicon is 120 MPa and ratio is 0.28. The maximum stress for the critical portion is 9.45 MPa according to the applied force. Lo west factor of safety for the needle holder is 12.6971. Figure 4.28 : S tress distribution on the needle holder

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58 4.4.2 Prototyping and Evaluating After modeling and finite element analysis testing, the next step was to make a physical prototype for evaluation Rapid Prototyping was used to construct the physical model from CAD data. As shown in Figure 4.29 a fused deposition modeling (FDM) system, Dimension SST 768, was used as a rapid prototyping machine to make the physical model. Fused Deposition Modeling (FDM) was developed by Stratasys and is a manufacturing process that creates a 3 D model using successive deposits of ABS material through a layer by layer approach. Figure 4.29: F used deposition m odeling (FDM) machine Dimension SST 7 68 The prototyping process enables designers to physically evaluate their designs and control their functions to make any necessary design changes. The prototyping process

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59 enables making such changes in a shorter time and allows a better vi sualization of the design For this study, a prototype of the proposed device was created by using the FDM machine mentioned previously There were three critical parts of this device to be prototyped: handle, toggle lever, and arms. The first prototypes of the handle, shown in Figure s 4.30a and 4.30b, were tested for ergonomics and functionality. The handle had to be ergonomic enough to allow extended usage during the operation. In addition, it had to enable easy control and functionality over the other p arts of the device such as the toggle lever and trigger. Based on the feedback from the surgeon, the design of the handle was gradually improved and led to the design and development of the current prototype, shown in Figure 4.31 The current handle allows easier access to the toggle and trigger with only one hand. (a) Handle 1 (b) Handle 2 Figure 4.30: Prototypes of the first version of the handle

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60 Figure 4.31: Prototype of the final version of the handle Additionally, the arms of the device were also prototyped to check the functionality. Arms w ere tested in order to see if: The needle can move easily between the a rms Their Their size is appropriate to enter through the 12 mm laparoscopic port After this first prototype shown in Figure 4.32 was created and tested, it was found to be not appropriate to meet these conditions. It was designed to have a maximum width of 10 mm, which was small enough to enter through the 12 mm laparoscopic port but based on discussions with the surgeon Therefore, the arms w ere re designed as shown in Figure s 4.33 and 4.34 in order to meet both of these conditions. In the current prototype, a sheath is used close the arms and allow th em to go through the 12 mm laparoscopic port Then, to grasp the tissue.

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61 Figure 4.32: Prototype of the first version of the arms Figure 4.33: Prototype of the final version of the arms

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62 Figure 4.34: Prototype of the final version of the arms assembled Once the device could be inserted through the laparoscopic port without any problem s the easy movement of the needle between the arms needed to be ensured. In order to do this, a tog gle lever, as shown in Figure 4.35 was developed and tested during the prototyping process. Its evaluation showed that the toggle lever can change the direction of the needle so that it can move between the arms. Also, F igure s 4.36 an d 4. 3 7 show the prototype of the main plunger and small plunger that are used to push both the needle carrier and the needle.

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63 Figure 4.35: Prototype of the final version of the toggle lever Figure 4.36: Prototype of the main plunger and small plunger Figure 4.37: Prototype of the main plunger and small plunger assembled

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64 In addition, Figure 4.38 shows the relationship between the flexible wire and the needle carrier. The flexible wire was used to be able to move the needle carrier by pushing the trigger. Figure 4.38 : Prototype of the final flexible wire After obtaining feedback from the surgeon and modi fying the current design according ly the prototype of the final version of the device was made Figur e 4.39 shows the prototype of the new suturing and knot tying device for laparoscopic surgery. Figure 4.39 : Prototype of the final version of the proposed device

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65 C hapter 5 Research Summary and Future Work T his chapter provides a summary of the research methodologies presented to develop and analyze the new suturing and knot tying device for laparoscopic surgery. The conclusions, including encountered challenges and limitations, are also discussed here, followed by a de scription of future research work. 5.1 Research Summary This research presented a new suturing and knot tying device for laparoscopic surgery. Qualitative data was collected through interviews with a surgeon and six in depth observations of minimally invasive surgeries at Tampa General Hospital. Different design concepts and mechanisms were generated using SolidWorks CAD software, and tested using SimulationXpress in order to identify dimensions, materials and expect ed performance of the design and its components. Based on the finite element analysis, it was determined that the materials selected for the components are expected to enable the components to perform their functions accordingly. The prototypes of the dev ice were made using a Dimension SST 768 FDM machine. The functionality of these prototypes were tested by the surgeon to ensure that the final design meets the needs and criteria that were initially determined. The results of

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66 the tests performed by the sur geon also confirmed that the working principle of the proposed device was feasible and ergonomic. The proposed suturing device aims to address the difficulties encountered by surgeons during the suturing procedure and to reduce the risks to the patients T his new device will eliminate the use of many different devices during the operation and allow the surgeon to suture with only one device. This will help reduce the time spent and potential complications during the suturing procedure Furthermore, the needle, which is sharp on both ends to allow passage through the tissue in both directions can use any type of suture in contrast with current devices that require the use of proprietary suture 5.2 Future Research Work This research proposed a new medical d evice for laparoscopic suturing and provided the feasibility analysis on the device assembly and components. Additional facilities, resources, and time are necessary to develop a complete working prototype that can be tested on animal models, which is out of the scope of this research work This will lead to a more complete e valuation of the device from the design and user perspectives

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67 References Adams, B. J., Schulam, G. P., Moore, G. R., Partin, W. A., & Kavoussi, R. L. (1995). Laparoscopic suturing device: Initial clinical experience. Urology, 46 (2), 242 245. Capio open access and standard s uture capturing devices. (2010). Retrieved November 10, 2009, from http://www.bostonscientific.com/Device.bsci?page=ResourceDetail&navRelId=1 000.1003&metho d=DevDetailHCP&id=10004521&resource_type_category_id=1 &resource_type_id=91&pageDisclaimer=Disclaimer.ProductPage Cetin, A. (2004). Applying product design methods to medical device design with a case study on home care devices. Izmir Institute of Technolog y, Izmir. Cronin, S., Frecker, M., & Mathew, A. (2007). Puncture force measurements on a porcine stomach. Gastrointest. Endosc., 65 (5), AB294. Cross, N. (2000). Engineering design methods (3th ed.). Milton Keynes, UK: John Wiley & Sons, Inc. Crow, K. ( 2020). Failure modes and effects analysis (fmea) Retrieved June, 20, 2010, from http://www.npd solutions.com/fmea.html a new s lip knot for arthroscopic surgery. Arthroscopy, 14 109 110. Delimar, D. (1996). A secure arthroscopic knot. Arthroscopy, 12 345 347. Dunitz, M., Sheth, S., & Studd, J. (2002). The scope of vaginal hysterectomy. European Journal of Obstetrics & Gynecology and Reproductive Biology, 115 (2). Endostitc h 10 mm suturing device. (2008). Retrieved November 5, 2009, from http://www.autosutur e.com/AutoSuture/pagebuilder.aspx?topicID=7407&breadcr umbs=0:63659,30691:0,309:0 Fleega, B. A., & Sokkar, S. H. (1999). The giant knot: A new one way self locking secured arthroscopic slip knot giant knot: Arthroscopy, 15 (4), 451 452.

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68 Food and drug admini stration (2010). Retrieved May, 15, 2010, from http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/Overview/Cl assifyYourDevice/u cm051512.htm Fries, R. C. (2001). Handbook of medical device design New York: Marcel Dekker Inc. Grace, P. A., P, B., & D., B. H. (1992.). Tying a laparoscopic knot. The British Journal of Surgery, 79 512. Gunderson, P. K. (1987). The half hitch knot: A rational alternative to the square knot. American Journal of Surgery, 154 538 540. Half hitches technique. (2010). Retrieved May, 10, 2010, from http://medical dictionary.thefreedictionary.c om/ Holmlund, D. E. (1974). Knot properties of surgical suture materials. Acta Chir Scand, 140 355 362. Hughes, P. J., Hagan, R. P., Fisher, A. C., Hold, E. M., & Frostick, S. P. (2001). The kinematics and kinetics of slipknots for arthroscopic bankart r epair. American Journal of Surgery, 29 738 745. Huhn, J., C. (2004). Intracorporeal suturing in minimally invasive surgery Retrieved February, 5, 2010, from http://veterinarynews.dvm360.com/dvm/Medicine/Intracorporeal suturing in minimally invasive surg/ArticleStandard/Article/detail/152907 Ilahi, O. A., Younas, S. A., Alexander, J., & Noble, P. C. (2004). Cyclic testing of arthroscopic knot security. Arthroscopy, 20 62 68. Jonassen, D. H., Tessmer, M., & Hannum, W. H. (1999). Task analysis methods for instructional design New Jersey: Lawrence Erlbaum Associates Inc. Jones, J. C. (1992). Design methods (2nd Edition ed.). New York: John Wiley & Johns, Inc. Kennedy, J. S. (1992). A technique for extracorporeal suturing J Laparoendosc Surg. 2 269 272. Khattab, O. S. (2008). Role of extracorporeal knots in laparoscopic surgery Retrieved December 15, 2010, from www.laparoscopyhospital.com/extracorporael_knot.html Liu, C. Y. (1993). Laparoscopic hysterectomy. In N. Osborne & G. Padial (Eds.), Operative laparoscopy for gynecologists (pp. 156 163). Omoha: IDI Publications. Lo, I. K. Y. (2008). Arthroscopic knot tying In J. S. Abrams & R. H. Bell (Eds.), Arthroscopic rotator cuff surger y (pp. 68 82). New York: Springer Link.

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69 Mini mally invasive surgery. (2010). Retrieved January 1, 2010, from http://www.mssm.edu/misc/defined.shtml Nguyen, J. K., & Bhatia, N. N. (1999). Transvaginal repa ir of paravaginal defects using the capio suturing device: A preliminary experience. J Gynecol Tech., 5 51 54. Pattaras, J. G., Smith, G. S., Landman, J., & Moore, R. G. (2001). Comparison and analysis of laparoscopic intracorporeal suturing devices: Pre liminary results. J. Endourol. 15 (2), 187 192. Ramasamy, S. (2005). Total quality management Tata McGraw Hill. Sanfilippo, J. S., & Solnik, M. J. (2008). Operative laparoscopy Retrieved December 15, 2009, from http://glowm.com/?p=glowm.cml/section_view&articleid=88 Stainless steel world. (2010). Retrieved June, 1, 2010, from http://www.stainless steel world.net/ Topel, H. (1996). Lap aroscopic suturing techniques. In J. S. Sanfilippo & R. Levine (Eds.), Operative gynecologic endoscopy (pp. 270 277). New York: Springer Verlag. Ulrich, T. K., & Krishnan, V. (January 2001). Product development decisions: A view of the literature. Management Science, 47 (1). Villacourt, M. (1992). Failure mode and effects analysis (fmea): A guide for continuous improvement for the semiconductor equipment industry: SEMATECH Inc.