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Scientific Basis for the Selection of Abdominal Fascial Closure Sutures Released: June 2008 Sponsored by Dannemiller Memorial Educational Foundation  Supported by an unrestricted educational grant from 
Faculty: Kant Y. Lin. M.D. Professor of Plastic Surgery Chief of Division of Craniofacial Surgery University of Virginia Health Systems Charlottesville, VA William B. Long III, M.D. Medical Director, Trauma Specialists, LLP Legacy Emanuel Hospital Portland, OR Richard F. Edlich, M.D., Ph.D. Distinguished Professor Emeritus of Plastic Surgery Biomedical Engineering, and Emergency Medicine Founder of the DeCamp Burn and Wound Healing Center University of Virginia Health Systems Director of Trauma,Prevention, Education and Research Trauma Specialists, LLP, Legacy Verified Level I Shock Trauma Center for Pediatrics and Adults Legacy Emanuel Hospital, Portland, OR Statement of Need: Continuing research into present and future methods of wound closure techniques makes it important for surgeons and surgical specialists to stay informed about the most up-to-date findings concerning all types of modern wound closure techniques. Surgeons must be able to restore the physical integrity and function of the injured or diseased tissue with the lowest incidence of infection and the most aesthetically pleasing result. Moreover, surgeons must have a scientific basis for selecting the most appropriate surgical suture and needle. Goal: The broad mission of this course is to train the participant to perform wound closure technique using appropriate sutures and needles. Objectives: At the completion of the training, the participant will be able to:
To receive credit, participants should, in order, view the objectives, read the educational material, then click on the link at the end of the activity to complete the post-test, evaluation, and then print the CME certificate. This activity should take approximately 1 hour to complete. This activity is available through June 30, 2011. No credit will be awarded after this date. Target Audience: This educational program is intended for general surgeons as well as other surgical specialists or physicians involved in wound closure. Accreditation: The Dannemiller Memorial Educational Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The Dannemiller Memorial Educational Foundation designates this educational activity for a maximum of 1.0 AMA PRA Category 1 Credit(s),TM. Physicians should only claim credit commensurate with the extent of their participation in the activity. The Dannemiller Memorial Educational Foundation is an approved provider of the California Board of Registered Nursing. Provider approved by the California Board of Registered Nursing, Provider Number 4229 for 1.2 contact hours. RNs outside California must verify with their licensing agency for approval of this course Disclosure Policy: The Dannemiller Memorial Educational Foundation requires that the faculty participating in a continuing medical educational activity disclose to participants any significant financial interest or other relationship (1) with the manufacturer(s) of any commercial product(s) and/or provider(s) of commercial services discussed in an educational presentation, and (2) with any commercial supporters of the activity. The presenting faculty reported no financial interest or affiliation that impacts on this activity. Dr. Long has nothing to disclose. Dr. Lin has nothing to disclose. Dr. Edlich has nothing to disclose. The content and views presented in this educational activity are those of the authors and do not necessarily reflect those of the Dannemiller Memorial Educational Foundation or U.S. Surgical. This material is prepared based upon a review of multiple sources of information, but it is not exhaustive of the subject matter. Therefore, healthcare professionals and other individuals should review and consider other publications and materials on the subject matter before relying solely upon the information contained within this educational activity. FOREWORD If this educational program heightens the surgeon's, resident's, and student's interest in the biology of wound closure and infection, the long years occupied in my search for improved methods of wound management would more than fulfill my expectations. Through the ages, selection of surgical sutures, needles and gloves has been an important consideration for surgeons. Despite these important historical considerations, some surgeons perceive surgical suture, needle and glove selection more as an art than as a science. For those artisans, the use of methods and materials for suturing and glove selection is usually a matter of habit, guesswork, or tradition. This approach to suturing has contributed to a growing concern that the suture selection as well as knot tying techniques employed by many surgeons are not optimal and that they incorrectly select sutures and use faulty techniques in tying knots, which is the weakest link in a tied surgical suture. When the recommended configuration of a knot ascertained by mechanical performance tests was compared to those used by board-certified general surgeons, only 25% of surgeons used the appropriate knot construction.1 Of the twenty-five gynecologists, mostly department heads, who were polled about their knot tying technique, most were convinced that they made square knots, even though their knot-tying techniques resulted in slipped knots that became untied.2 When a knotted suture fails to perform its functions, the consequences may be disastrous. Massive bleeding may occur when the suture loop surrounding a vessel becomes untied or breaks. Wound dehiscence or incisional hernia may follow knot disruption. As with any master surgeon, he/she must understand the tools of his/her profession. This linkage between a surgeon and surgical equipment is a closed kinematic chain in which the surgeon's power is converted into finely coordinated movements that result in wound closure with the least possible scar and without infection. The extensive clinical experience's of the gifted plastic surgeon, Dr. Kant Lin and trauma surgeon, Dr. William B. Long, were essential ingredients of this empowering continuing education program. Dr. Kant Lin a internationally recognized craniofacial surgeon and Dr. William Long, Medical Director of Trauma Specialists, LLP, have been viewed by many of their colleagues as the Paderewski's of the scalpel who has brilliant results in surgery. It is my belief that these surgeons have transformed surgical suture and needle selection from a ritual practice to a surgical discipline. Early in my career, surgical selection of sutures and needles was largely based on testimonials and anecdotal experiences of senior surgeons. Today, modern surgeons select sutures and needles on the basis of well-controlled, randomized clinical and experimental trials. Having a keen appreciation of surgical education, they have modeled the format of this course to be an individualized learning environment. The course is designed to teach each participant the scientific basis for suture and needle selection as well as to illustrate the appropriate surgical techniques involved in abdominal fascial wound repair. Richard F. Edlich, M.D., Ph.D. Distinguished Professor Emeritus of Plastic Surgery and Professor of Biomedical Engineering Founder of the DeCamp Burn and Wound Healing Center University of Virginia Health Systems Editor-in-Chief of the Journal of Long-Term Effects of Medical Implants Director of Trauma Prevention, Education and Research Trauma Specialists, LLP, Legacy Emanuel Hospital Portland, OR ABDOMINAL FASCIAL SUTURE CLOSURE Biology of musculoaponeurotic repair Early studies on the healing of musculoaponeurotic incisions utilized excised segments and were specifically designed to place the greatest stress on the wound rather than distributing tension throughout the entire abdominal wall. Most of these studies demonstrated that the excised segments of tissue were never as strong as that of unwounded tissue. In the study by Fast and colleagues3 of the gain in breaking strength of sutured paramedian incisions in rabbits, the wound with sutures present was 41.9% as strong as the undisturbed opposite side immediately after closure. This value dropped slightly during the next three days and then rose sharply, approaching 80% at 15 days. At six weeks after surgery, the sutured abdominal incisions never regained their postoperative strength, remaining at about 80% of the value. With a similar experimental model in the rabbit, Nelson and Dennis4 assessed the strength of healing paramedian incisions. The results from the groups of animals in which the suture materials were removed before testing demonstrated that the suture contributed a major amount of strength to the healing wound during the first 14 days after wounding, after which the suture had a negligible role in wound repair. In the six weeks of observation, the healing abdominal wall wounds never attained the full strength of the unwounded side, remaining at about 80% of that value. In an investigation of the healing of lumbodorsal aponeurotic incisions in rabbits, Douglas5 noted that the strength of any of the wounds could not be detected until the sixth day after wounding. All wounds showed measurable strength by the eighth day, and thereafter, a rapid increase until about the end of the second month, when the curve of healing began to flatten out. Subsequently, a slow increase in strength was detectable, which continued throughout the duration of the study (one year). At the end of two weeks, the wound approached 20% of that of unwounded tissue; at the end of one month, 50%; at two months, 60% to 80%; and one-year values, up to 90%. This investigator concluded that the repaired aponeurosis never reaches the strength of the unwounded tissue and never before four months after the incision. Adamsons and Kahan6 demonstrated that musculoaponeurotic wounds in rabbits gained most of their strength during the first 30 days after wounding, after which the increase was minimal. Despite the most rapid gain in strength during the first 30 days, the muscle wound regained only 57% of the strength of the uninjured contralateral muscle. The tensile strength measured over the same cross-sectional area was identical in wounds of skin and muscle during the first nine days of healing. The subsequent pattern of repair in these two tissues, however, was different. The skin wound gained tensile strength at a rapid pace, whereas the wound of muscle demonstrated a slow increase. In studies of incised fascial wound in rabbits, Lichenstein and co-workers7 reported that the wound strength after suture removal markedly increased during the first two weeks after wounding, after which the rate of gain was gradual, increasing to 41% at two months. The wounds with intact nonabsorbable sutures were as strong the moment the operation was completed as they were two months later, 70% of the strength of the unwounded tissue. This relative weakness of the musculoaponeurotic wounds in the rabbits may be species specific because it was not encountered in the studies by Adamsons and colleagues6 on repaired paramedian incision in guinea pigs. Healing paramedian incisions in guinea pigs tested with nonabsorbable sutures in situ regained the strength of original uninjured tissues by the ninth day after wounding and exceeded it significantly by the forty-fifth day. Healing paramedian incisions tested with sutures removed regained 80% of the strength of the original uninjured tissue by the ninth day after wounding and 114% by day 45. Experimental models in which the peritoneal cavity of the intact animal is distended to measure the burst strength of the abdominal wound simulate the clinical situation more closely than the breaking or tensile strength studies. With this abdominal wound burst model, Kon and associates8 reported that abdominal disruption often occurred at a site distinct from the wound at one, two, and six months after wounding, indicating that the wound was stronger than the unwounded abdominal tissue. Local and mechanical factors appear to be more important in dehiscence than systemic factors. Bringing a drain or stoma through the wound will obviously compromise the closure and contaminate the wound. Wound infection has been frequently implicated as a contributing factor to wound dehiscence and the development of incisional hernia. Smith and Enquist9 found that a standardized staphylococcal wound infection produced significantly weaker fascial wound than the controls. Wound dehiscence is clearly associated with causes of increased intraabdominal pressure to include abdominal complications (vomiting, ileus, or obstruction), pulmonary problems (atelectasis, bronchitis, or pneumonia), or the nature of the operation (repair of diaphragmatic hernia).10 Because the direction, length, and location of the abdominal incision are not important determinants of wound disruption, primary consideration should be given to the location of the incision that provides adequate exposure to perform the operation. Since the advent of synthetic absorbable sutures, polyglycolic acid and polyglactin 910, several randomized prospective studies in humans have demonstrated that they are equal to nonabsorbable sutures, including wire, in ensuring wound integrity. The recently introduced monofilament absorbable suture, Glycomer 631, may be a suitable alternative to a nonabsorbable suture because it retains approximately 50% of its tensile strength three weeks after implantation. In a longer term experimental study, polydioxanone suture has provided a degree of protection against wound bursting that is comparable to that of polypropylene or Teflon-coated Dacron sutures.8 With nonabsorbable and synthetic absorbable sutures, wound disruptions are caused by the fascia tearing at the site of the suture. Most experimental studies demonstrated that placing the suture farther from the cut edges of the fascia reduced the risk of wound disruption. Sanders and colleagues11 reported that placing the suture 5 mm from the cut edges of the fascia resulted in a higher wound bursting strength than 1 to 2 mm from the fascial edges. Leaper and colleagues12 recorded the suture holding strength of abdominal wall structures in cadavers and noted that the holding strength of sutures placed 1 cm from the fascial edge was 7.16 kg compared with 3.93 kg for sutures placed 0.5 cm from the wound edge. In another study, Tera and Åberg13 measured the holding power of sutures in human musculoaponeurotic incisions. The results of their landmark investigation provide a scientific basis for the selection of suture placement and the type of laparotomy incisions. After evaluating a variety of laparotomy incisions (linea alba incision, transverse incision through linea alba, McBurney's incision, pararectal incision, paramedian incision), they reported that the strongest closure was obtained in midline incisions through the linea alba. When the sutures were placed laterally to the transition between the linea alba and rectus sheath, the paramedian incision was found to give the weakest closure, followed by the only slightly stronger pararectal incision. The optimal depth of the suture bite in the linea alba had to be at least 4 mm. The ideal interval between sutures approached 6 mm. Most surgeons who use midline incision closure advocate placing the suture at least 1 cm from the divided edge of the fascia, a distance that would be beyond this transition zone. Whipple and Elliott14 indicated that tying sutures too tightly caused strangulation of the tissue with ischemic necrosis and was the most common error in abdominal wound closure. The suggestion was confirmed by studies of Nelson and Dennis,4 Haxton,15 and Sanders and associates.11 These investigators reported that tight tying of interrupted sutures resulted in a lower wound strength than sutures tied when the wound edges were approximated. The selection of a wound closure technique must also take into account the dynamic changes in wound length during distention.16 Measurements of the abdominal girth and xiphoid pubic distance before and after closure demonstrate that abdominal distention may lengthen the wound by 30%. When the stitch interval is 1 cm, it will become 1.33 cm when the wound is lengthened by 30% during abdominal distention. The continuous suture can accommodate this increase in the length of the incision by having an adequate reserve of suture length in the wound. Consequently, the continuous suture distributes its tension throughout the wound, limiting the forces on the tissues encircled by the suture. With interrupted closure, the suture cannot easily accommodate these changes in incisional length, and the tension remains isolated to each suture loop. With an intact animal model, Poole and co-workers17 demonstrated that the continuous suture technique was associated with greater wound bursting pressure than the simple interrupted suture or figure-of-eight mattress suture. There are several clinical reports in which continuous sutures have been used with excellent results. In a prospective randomized trial of both vertical and oblique incisions, Richards and colleagues18 found no difference in the wound dehiscence rate or incidence of incisional hernia between continuous and interrupted (Smead-Jones) suturing. In addition, Stone and associates19 showed that continuous suturing resulted in a comparable incidence of dehiscence to interrupted sutures and had the average saving of 26 minutes in anesthesia time. Most prospective studies of wound disruption report incidence rates of 1% to 3% after major abdominal operations.20 Mortality after dehiscence is high, ranging from 9.4% to 43.8%. Factors associated with an increased risk of wound dehiscence include male sex, advanced age, hypoproteinemia, malnutrition, obesity, malignant disease, treatment with steroids, and uremia.21 Experimental studies have confirmed that uremia has an adverse effect on wound repair.22 Kursh and associates23 confirmed that uremia had a deleterious effect on wound repair by measuring the tensile strength of skin wounds and the amount of collagen formation in polyvinyl sponges implanted subcutaneously. The uremic rats had a significant reduction in wound tensile strength and collagen accumulation compared with that in the control animals. It was also noted that the uremic animals had a significant decrease in caloric intake and final body weight, suggesting that nutritional factors were responsible for the demonstrated poor healing capacity associated with uremia. In another experimental study by Kursh and colleagues24 a group of nonuremic animals was parallel fed a diet and caloric intake identical to that of the uremic animals. The parallel fed rats had a wound strength that closely approximated the values of the uremic rats and was significantly less than that of the control rats. Accordingly, this investigation lends further evidence that the mechanism of reduced wound healing capacity associated with uremia is on the basis of reduced nutrition. Biology of peritoneal repair The most important principle of healing of the peritoneum is that the entire surface is covered by mesothelial cells simultaneously, not gradually from the border as in epidermization of the skin wound.25 Regardless of the size of the defect, a mesothelial surface indistinguishable from normal peritoneum will be reconstituted within a few days (3 to 4 days) in the rabbit, rat, dog, and human. The mesothelial defect is covered primarily by the freefloating peritoneal macrophages that contact the denuded surface. A centripetal spread of uninjured cells from the surrounding mesothelium and transformation of stem cells in the base of the wound contribute to a lesser degree to the repair process. Peritoneal repair can be complicated by the development of intraabdominal adhesions, which are the most common cause of acute intestinal obstruction. Adhesions that develop after abdominal operations represent a vascular response by surrounding structures to the stimulus of ischemic tissue or a foreign material within the peritoneal cavity. Foreign materials that elicit adhesions are gauze, swabs or cotton wool, glove lubricants (cornstarch and talc), and drains. Under controlled conditions in every species that has been studied, the fibrous band produced between the peritoneal scar and some other structure can take origin from a suture. Conolly and Stephens26 reported that in rat laparotomies closed without sutures the peritoneum healed with a decreased incidence of adhesions to the wound. Hubbard and associates27 also demonstrated that the only discernible effect of peritoneal closure by sutures was to increase the formation of adhesions. The incidence of adhesion formation is not reduced by the use of less reactive sutures.28 Some surgeons justify sutural closure of peritoneum, suggesting that dehiscence is more likely if no sutures are used in the peritoneum. Karipineni and co-workers,29 Ellis and Heddle,30 Kapur and colleagues,31 and McFadden and Peacock32 have shown that the absence of sutural closure of the peritoneum does not reduce wound strength or predispose to wound dehiscence. The therapeutic implications of these observations on the biology of peritoneal repair are being ignored by most surgeons. Careful avoidance of all foreign materials is mandatory. No attempt should be made to reconstruct a peritoneal defect. Whenever possible, serosal defects should be left open rather than being pulled together under tension. The peritoneal portion of abdominal incisions should never be approximated by sutures. Continuous suture closure of linea alba The midline epigastric incision is an almost bloodless incision because no muscle fibers are divided. It can also be extended the full length of the abdomen by curving around the umbilicus. The incision is placed in the midline and extends from the tip of the xiphisternum, usually to about 1 cm above the umbilicus (Figure 1). Using a No. 10 knife blade, the surgeon will deepen the midline skin incision through the subcutaneous tissue, the linea alba, and underlying peritoneum to expose the abdominal cavity. The extraperitoneal fat is abundant and vascular in the upper half of the incision. The suspensory ligament of the liver is best avoided by opening the peritoneal cavity well to the left or the right of the midline under the rectus muscle (Figure 2). The goal of this course is to teach you to repair musculoaponeurotic incisions in the linea alba using a continuous suture closure. Continuous suture closure of the linea alba has definite, distinct advantages over interrupted suture closure. First, continuous suture closure can be accomplished more rapidly than interrupted suture closure. This time saving is related to the short time involved in constructing knotted suture loops for the continuous suture closure. There is one knotted suture at each corner of the incision.   In contrast, interrupted suture closure requires knot construction for each separate suture loop. Another advantage of the continuous suture is that it accommodates to the abdominal distension with a subsequent increase in the length of the incision. Continuous suture closure of the linea alba can be accomplished by two different techniques. In the first technique, the needle pathway is at a 90° angle to the incision edges and results in a visible suture that crosses the incision edges at a 65° angle. This technique is technically easier to accomplish than one in which the needle pathway is oblique to the incision edge. Consequently, we will be demonstrating this first technique for continuous suture closure. The surgeon begins the continuous suture with an interrupted suture placed 1 cm from either end of the incision. The taper point needle with its attached monofilament absorbable 0-gauge suture is passed in a direction toward the surgeon, rather than away from the surgeon. The exit and entrance points of the first interrupted suture are at least 1 cm from the incision edges. A suture of this depth passes through the linea alba at a point lateral to the transition between the linea alba and the rectus sheath without penetrating the underlying peritoneum. The distance between the exit and entrance points of the interrupted musculoaponeurotic suture is at least 2 cm (Figure 3).   After completion of the first suture, construct a secure three-throw square knot and cut only one free suture end 3 mm from the knot. Position the knot so that it lies at a point furthest from you. Holding the fixed suture end parallel to the wound, the taper point needle should be passed through the linea alba 4 mm from and adjacent to the knot. This needle entrance site is 1 cm from the incision edge and 4 mm from the first interrupted suture. Pass the needle beneath the linea alba 90° to the incision and exit 1 cm from the incision edge through the linea alba of the opposite side of the incision without penetrating the underlying peritoneum (Figure 4). The next suture then crosses the incision at a 65° angle to the incision to an entrance point 1 cm from the incision edge. Again, the needle is passed beneath the incision at a 90° angle to the incision to continue placement of the suture. After each sutural passage, the surgeon holds the suture taut to ensure accurate approximation of the incised edges of the linea alba. The passage of the suture is repeated as described until the incision edges are almost completely approximated by the continuous suture with one remaining needle passage necessary for complete repair. At a point 4 mm form the end of the incision, pass your taper point needle parallel to the incision, through the linea alba 6 mm from the previous exit point. This next to last needle passage traverses the incision at an angle of 90° to the incision and should enter and exit at points that are 1 cm from the incision edge and 4 mm from the incision end. The continuous suture ends as an interrupted suture 1 mm from the incision end, which is accomplished with care to leave a suture loop remaining during suture pull through. This suture loop will be used in knot construction. Knot construction is accomplished using an instrument tie with the fixed suture end of the suture and the remaining suture loop. When constructing a secure knot with a suture loop and fixed suture end attached to a needle, we prefer a six-throw square knot with 3 mm ears, rather than a three-throw knot, to ensure knot security.6 It is advisable to cut the needle from the fixed suture end with surgical scissors before performing the instrument tie. After continuous suture closure of the linea alba, the skin is closed with a continuous percutaneous suture as previously described (Figure 5). Consequently, closure of the midline epigastric incision is accomplished by a continuous suture closure of the linea alba, followed by a continuous percutaneous suture (Figure 6).   Interrupted suture closure of linea alba Despite the demonstrated merits of continuous suture closure of linea alba, some surgeons continue to use interrupted suture closure techniques for linea alba closure. Synthetic braided absorbable sutures are often used for interrupted closure of the linea alba. The scientific basis for the selection of the synthetic braided absorbable suture is based on the following performance characteristics: (1) drag force, (2) first throw security of a surgeon's knot squared (2=1), (3) knot reposition, and (4) knot security. CONCLUSION Your success in achieving optimal wound closure using sutures and their attached needles will depend on several factors. First, you must have all of the appropriate sutures and attached needles that are necessary to achieve wound closure. Inadequate instruments will defeat the efforts of even the master surgeon. Second, mastery of surgical skills using sutures and needles requires repetitive practice. Surgeons who do not have adequate psychomotor skills will not achieve an excellent result even with the finest sutures and their attached needles. Third, select the most appropriate sutures with their attached needles based on the biology of wound repair and infection and the biomechanics of sutures and needles. Finally, you must always use a double glove hole indication system that accurately detects holes in the gloves. In the event of a needle stick exposure during surgery, operating personnel must follow carefully the postexposure prophylaxis plan against blood borne deadly viral infections. As you perfect your surgical discipline, share this information with your colleagues and encourage them to participate in this training program. In addition, we encourage each of you to evaluate carefully the clinical results of your wound closure with sutures and strive to devise new and improved techniques that are based on scientific investigations rather than testimonials. References
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