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Improved performance through functional finishes

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Improved performance through functional finishes

     Volume 2, Issue 2, Spring 2002

    Medical Textiles: Application of an Absorbable

    Barbed Bi-directional Surgical Suture

     1112 Philip P. Dattilo, Jr., Martin W. King, Nancy L. Cassill, Jeffrey C. Leung1College of Textiles, North Carolina State University, Raleigh, NC 27695-8301 and 2Quill Medical, Inc., Research Triangle Park, NC 27713

    ABSTRACT

    Today’s medical textile market is producing state of the art polymeric textile implantable devices that are redefining traditional materials and methods of surgery. These sophisticated high-tech polymer materials are engineered for specific uses in surgical and interventional procedures. One of the new biotextile products is an absorbable bi-directional barbed surgical suture that does not require surgical knots for wound closure. This novel idea has the attention of many physicians and surgeons where wound closure or tissue approximation is needed. The barbed suture has the potential to change the way wound closure is perceived in various clinical fields of surgery and veterinary medicine.

KEYWORDS:

    prosthesis (artificial arteries), heart valves Introduction

     The medical textile industry has (Figure 2), and sutures.

    diversified with new materials and

    innovative designs. Evolving polymer

    technology has yielded a wide range of

    applications of implantable medical textile

    devices or biotextiles. King has defined

    biotextiles as: “structures composed of

    textile fibers designed for use in specific

    biological environments (e.g. surgical

    implants, biomass reactors), where their

    performance depends on their interactions with cells and biological fluids as measured Figure 1. Cardiac support device (Courtesy in terms of their biocompatibility and of Acorn Cardiovascular, Inc) 1biostability” . Applications of implantable biotextiles range from polymeric valves Sutures are the most common biotextile through woven or knitted artificial ligaments implantable devices due to their diverse to polymeric wound closure devices. usage in surgical procedures. They are used Examples of implantable biotextiles include to achieve wound closure whenever tissue cardiac support devices (Figure 1), vascular

    separation has occurred due to an incision, other techniques for wound closure using, puncture, abrasion, or other injury. for example, clips, staples, or tissue

     adhesives have been developed in recent

    years, the suture continues to be the wound

    closure device of choice for most procedures.

    This is due to the extensive research and

    data that has been collected over time

    describing the exact behavior of suture

    materials and their tissue reactions in vivo.

    In 1999, there were 41.3 million inpatient

    and 31.5 outpatient surgeries performed in

    the United States. During these surgical

    procedures, sutures were the most common

    form of wound closure device. This number

    of interventions produced a market size of

     $210 million worth of surgical sutures. Figure 2. Bioprosthetic aortic valve with knitted Today’s Sutures polytetrafluoroehtylene sewing ring Today’s suturing techniques are (Courtesy Edwards Lifesciences) responsible for two main adverse effects. Sutures require knots so as to ensure optimal History of Sutures and Wound Closure tissue closure strength. The goal of wound The history of wound closure dates back closure is to bring the edges of the wound 1to 5000-3000 B.C., the origins of surgery. together not only with sufficient strength to Early wound closure devices were made of prevent dehiscence, but also with a minimal natural materials such as flax, silk, linen residual tension and compression of the 2strips, and cotton. These natural materials tissue. First, the knot tying process leads to were lubricated in oil and wine prior to residual forces and distortion of the tissue application so as to reduce tissue drag and that can cause impaired blood perfusion 2create a cleaner wound closure procedure. through the capillaries and can compromise Another early form of a wound closure the healing process. The body’s natural technique involved the use of the mandibles reaction to foreign materials causes the 3of soldier ants. With the development of second adverse effect. Once implanted, synthetic polymers and fibers, synthetic sutures provoke a significant inflammatory sutures were introduced into the market. response, particularly at the knot site, These sutures allow for designers to because the knot represents a major mass of engineer the polymer configuration, the fiber foreign material that is concentrated in a 5type and size, and the surface lubricant . This has led to a continuing small volumeand/or coating for specific applications. debate among surgeons as to how many Today, surgical sutures come in many forms: throws should be incorporated into a natural, synthetic, nonabsorbable, and surgical knot so as to maximize strength and absorbable. The application depends on the minimize the tissue reaction. surgeon’s preference as well as the specific In 1967 A.R. McKenzie published an site and clinical technique being performed. article about an experimental multiple Market Size barbed suture. He stated that during Surgical sutures serve as a means of insertion the barbed suture minimized tissue wound closure and tissue approximation. damage, which led to milder foreign-body 6Sutures bring together and maintain the reaction. His study showed that barbed tissue on each side of a wound until the nylon sutures could be used successfully in 6natural healing process has provided a flexor tendon repair. However, the nylon 4sufficient level of wound strength. While barbed sutures had to be removed after a

    four week period, which led to additional directional Barbed Suture. MS Thesis. late surgical trauma. North Carolina State University. 2002.)

     Absorbable Bi-directional Barbed Suture The monofilament sutures contain up to 78 In 1992, Dr. Gregory Ruff of Duke barbs manufactured in a spiral pattern University Medical Center started working around the circumference of the suture. The on an idea of a barbed suture for cosmetic barbs are divided into two groups facing applications. Dr. Ruff took the idea of a each other in opposing directions around the barbed suture and applied it to an absorbable mid-point (Figure 4). The two sets of barbs suture material made of polydioxanone. His divide the suture into two sections, right and 7work is defined in US Patents 5,342,376 left. 8and 6,241,747 B1. The advantage of using an absorbable polymer suture is that it does

    not need to be removed and it does not

     require knots to make it secure. The Figure 4. Bi-directional barbed suture knotless design has significant potential in showing midpoint (Courtesy of Quill reducing scar tissue due to the absence of a Medical, Inc.) significant foreign- body reaction caused by knots. The barbed configuration anchors the Using image analysis techniques, the suture into the tissue and provides adequate geometry of the barbs has been tissue adhesion while the wound heals under

    characterized by defining the cut angle (), minimum residual tension and pressure.

    depth of cut (D), length of cut (L), the cc The success of this novel wound closure

    distance between cuts, and the number of device requires the suture geometry to be

    cuts per unit length (Figure 5). well characterized and monitored during

     manufacture for two reasons: quality

    control (measuring uniformity of the barb

    geometry) and the need to determine the

    effect of tissue holding capacity and the barb

    geometry. Quill Medical, Inc. currently

    produces this barbed monofilament suture

    from polydioxanone in size 0, (size 0 has a diameter of 0.30 to 0.39 mm), while other Figure 5. Geometry of individual barb sizes are under development (Figure 3). (Source: Dattilo, P. Absorbable Bi-

    directional Barbed Suture. MS Thesis. North

    Carolina State University. 2002.)

    The length of the cut is a calculated value

    using the following formula:

    Dc Lc;;sin180

    These values are measured, recorded, and

    analyzed statistically on a routine basis. No

    significant differences have been found

     between the left and right sections of the

    barbed sutures, indicating that the barbs are Figure 3. Barbed polydioxanone suture deployed using a controlled, uniform and (Source: Dattilo, P. Absorbable Bi-mirrored geometry.

    ideal candidate for internal wound closure.

    Current sutures require the tying of surgical Applications of Barbed Sutures

     These bi-directional barbed absorbable knots. The throws of these knots are often sutures can be used in a range of different pushed through a transdermal cannula, surgical procedures. The suture can be used which can be tedious and difficult for the in dermal tissue approximation, internal surgeon as well as resulting in inferior knot 9wound closure, and tendon repair. These performance. The knotless barbed suture diverse applications of the suture will allow can also be applied through a cannula and, the product to generate a range of market without the need for tedious knot throwing opportunities. and pushing, it is likely to reduce surgery

     Dermal tissue approximation currently time and create a more consistent method uses a variety of wound closure techniques for tissue approximation.

    including tissue adhesives. A major issue in McKenzie’s article describes the use of a dermal wound closure is the cosmetic results nylon barbed suture for repair of the long 6of tissue approximation. The use of flexor tendon of the hand (Figure 7).

    polydioxanone and the barbed configuration

    allows the suture to be completely sub-

    dermal, meaning there will be no visible

    signs of a wound closure device during and

    after healing (Figure 6).

     The barbed configuration does not Figure 7. Barbed suture in tendon repair require surgical knots for adequate tissue

    application strength. A knotless configuration greatly

    (Source: McKenzie, A.R. An experimental reduces the amount of scar tissue that is

    multiple barbed suture for the long flexor created during healing in vivo.

    tendons of the palm and fingers. Preliminary Internal wound closure yields the best

    report. JBone Joint Surg Br. 1967 results when using an absorbable material.

    Aug;49(3):440-7.) Using nonabsorbable wound closure

     material requires

    The knotless designed suture increases the

    flexibility and longitudinal movement of the

    tendon that would normally be limited by

    the presence of knots. The polymer suture

    can be engineered to maintain the required

    strength for the duration of the complete

    healing process. In addition, the absorbable

     barbed suture does not require removal after Figure 6. Sub-dermal suture the repair is healed, thus reducing the (Source: Sadick NS, D’Amelio DL, number of visits to the surgeon as well as Weinstein C. The modified buried vertical the trauma associated with a follow-up mattress suture. A new technique of buried intervention. absorbable wound closure associated with excellent cosmesis for wounds under tension. Future Trends J Dermatol Surg Oncol. 1994 Future experimentation, design, and Nov;20(11):735-9.) engineering will lead to better understanding of the characteristics of the barbed suture. removal of the device after the wound has The initial product has given positive data healed. This can lead to additional visits to when compared to current sutures that the physician or surgeon and the use of more require knots. Experiments are currently invasive surgical procedures. The fact that being performed that test the tissue holding polydioxanone is absorbable makes it an capacity of the sutured wound under stress.

    The use of micro-electronic mechanical systems (MEMS) is being considered to better understand the reaction between tissue and the individual barbs. Future design applications will look at how different barb geometries affect the performance of the suture and its ability to hold different types of tissue. Also micro-machining

    technologies are being evaluated to ensure the optimum control over the different manufacturing processes.

     Because the bi-directional barbed suture reduces problems that are associated with current sutures on the market, it is believed that this novel product will have a significant impact on the future wound closure industry. This century’s new textile products will continue to expand the traditional thinking about sutures and wound closure devices.

References

     1 King, M.W. Overview of opportunities with

     in medical textiles. Canadian Textile

    Journal.

     2001 July/Aug; 118(4):34-36.

    2 Chu, C.C., J.A. von Fraunhofer, and H.P.

     Greisler. Wound Closure Biomaterials and

     Devices. Boca Raton, FL: CRC Press,

    1997.

     3 Hiller, Lejaren. Sutures in Ancient

     Surgery. Brooklyn, NY: Davis and Geck,

     1927-1938.

     4 Reiter, D. Methods and materials for

     wound management. Otalarynogol Head

     Neck Surg. 1994 Jun;110(6):550-6.

    Review.

    5 van Rijssel EJ, Brand R, Admiraal C, Smit I,

     Trimbos JB. Tissue reaction and surgical

     knots: the effect of suture size, knot

     configuration, and knot volume. Obstet

     Gynecol. 1989 Jul;74(1):64-8.

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