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PubMed2006

Pullout strength of meniscal repair after cyclic loading: comparison of vertical, horizontal, and oblique suture techniques.

This in vitro biomechanical study with cyclic loading compared the pullout strength of vertical, horizontal, and oblique sutures used for meniscal lesion repair. Following repair of vertical longitudinal lesions created in bovine medial menisci, three groups of seven specimens (vertical, horizontal, and oblique sutures) underwent cyclic loading in a randomized test order (5 mm/min, cycling between 5 and 50 N at 1 Hz for 100 cycles) prior to load to failure testing (5 mm/min). Displacement did not differ between groups during cyclic or load to failure testing. Construct stiffness during cyclic testing was superior for the oblique suture (6.9 +/- 1.5 N/mm, P = 0.007) and the vertical suture (6.4 +/- 7 N/mm, P = 0.03) groups compared to the horizontal suture group (4.4 +/- 0.52 N/mm). The oblique suture (171.9 +/- 25.9 N, P < 0.0001) and the vertical suture (145.9 +/- 32.3 N, P = 0.001) groups displayed superior load at failure compared to the horizontal suture group (88.8 +/- 8.2 N). Construct stiffness during load to failure testing did not differ between groups. Suture rupture was the failure mode for all specimens of the oblique suture group. Suture rupture was the failure mode for 57% (4/7) of the vertical suture group with the remaining specimens (3/7, 43%) failing from intact suture pullout through meniscal tissue. All horizontal suture group specimens failed by intact suture pulling through meniscal tissue. With comparable stiffness during cyclic testing, comparable load at failure as vertical sutures, and less evidence of intact suture pullout through the meniscus, an oblique suture technique may combine the beneficial characteristics of vertical (superior biomechanical strength) and horizontal (ease of application, longer sutures with a tendency to cover a larger meniscal tissue area) suture-repair techniques.

Animals↗
PubMed2001

Tensile strength of cadaveric fascia lata compared to small intestinal submucosa using suture pull through analysis.

PURPOSE: The modified pubovaginal sling has become popular as first line treatment for stress urinary incontinence. With the increasing use of cadaveric fascia as a sling material, widespread shortages are prevalent, hence limiting its availability. The increased morbidity with the use of synthetic sling materials and autologous fascia has stimulated investigation of other sling materials. We evaluated the tensile strength of 4 suture types, and compared tensile strength of cadaveric fascia lata to porcine small intestinal submucosa using suture pull through analysis to assess their efficacy and durability for use in anti-incontinence procedures. MATERIALS AND METHODS: Suture breaking load was determined using 2 and 1-zero polypropylene suture, and 2 and 1-zero polyglactin suture. Freeze dried gamma irradiated human fascia lata and freeze-dried small intestinal submucosa were evaluated. Suture was fixed to sling material using the cross fold technique. Mean suture breakage and suture pull through were determined using a tensionometer by measuring the load applied to the sling/suture system. Statistical analysis was performed. RESULTS: Mean suture breakage load was greatest with 1-zero polyglactin (8.10 pounds) and least with 2-zero polypropylene (3.68 pounds). Mean suture breakage strength was similar for 1-zero polypropylene and 2-zero polyglactin at 5.26 and 5.40 pounds, respectively. Mean suture pull through load using 1-zero polypropylene suture and the cross fold technique was 5.64 pounds for cadaveric fascia and 2.74 pounds for small intestinal submucosa (p <0.0001). Maximum load was limited by the suture strength when using cadaveric fascia, whereas, maximum load was limited in small intestinal submucosa by its inherent tensile strength. However, using a new technique for suture fixation to the small intestinal submucosa, we were able to increase significantly mean suture pull through load to 3.36 pounds (p = 0.008). Additionally, with this new technique small intestinal submucosa allowed gross stretching before suture pull through that was not seen with cadaveric fascia. CONCLUSIONS: Despite the current standard use of 1-zero polypropylene suture for pubovaginal sling fixation, our data suggest that 1-zero polyglactin suture is the strongest, and its use with pubovaginal sling fixation warrants further investigation. Using the cross fold technique and 1-zero polypropylene suture, tensile strength was greatest with cadaveric fascia compared to small intestinal submucosa. Although small intestinal submucosa was not as strong as cadaveric fascia, our persuasive preliminary data suggest that further investigation is warranted in the use of small intestinal submucosa and other suture fixation techniques, and its observed stretch capacity. Hence, with further studies small intestinal submucosa may remain a viable option for pubovaginal sling material.

Cadaver↗
PubMed2005

Human gingival tissue reactions to silk and expanded polytetrafluoroethylene sutures.

BACKGROUND: Wound closure by suturing is a critical and significant event in general as well as in oral surgery. Information regarding tissue reactions to different suture materials appears incomplete and inconsistent, particularly in humans. Thus, the purpose of the present study was to evaluate clinically and histologically tissue reactions to silk and expanded polytetrafluoroethylene (ePTFE) suture materials placed in human oral tissues. METHODS: Twelve patients undergoing periodontal treatment, who had bilateral periodontal defects in the maxillary premolar and molar region scheduled for resective surgery, were included. In each patient, one single interrupted ePTFE suture (CV-5) and one single interrupted silk suture (4-0) were inserted in gingival tissues in contralateral jaw quadrants 10 days prior to scheduled surgery and a second set of sutures was inserted at 7 days prior to surgery. After placement, the length of the suture embedded in the tissue as well as the slack of the suture loop were measured and tabulated. The measurements were repeated on the day of surgery. At this time biopsy specimens, including the suture loop and surrounding tissue, were harvested and processed for histologic analysis. The inflammatory response was evaluated by measuring the thickness of the perisutural epithelium and the diameter of the connective tissue infiltrate, by estimating the proportion of inflammatory cells to epithelial cells, and by recording the presence or absence of bacterial plaque along the suture track. RESULTS: At 7 days, silk sutures showed a significantly higher degree of slack of the suture loop than did ePTFE sutures (P= 0.02), while the difference was not significant at 10 days (P= 0.21). The mean change of "tissue bite" was greater for silk compared to ePTFE at 7 as well as at 10 days. However, none of the differences were statistically significant (P= 0.43). The thickness of the perisutural epithelium increased significantly from 7 to 10 days for both suture materials, while the difference in proportion of inflammatory cells to epithelial cells was not significant (P= 0.43). An overall significantly greater diameter of connective tissue infiltrate was present around the silk sutures. Bacterial plaque was detected in 10 of 11 silk and four of 11 ePTFE suture channels at 7 days, and eight of 10 and four of 11 suture channels at 10 days. CONCLUSIONS: The results revealed that placement of sutures in gingival tissues elicits an inflammatory reaction and that the magnitude of this reaction may vary with the suture material used. Braided silk sutures apparently cause a more extensive inflammatory tissue reaction in an environment characterized by moisture and infectious potential.

Adult↗
PubMed2000

Transforming growth factor-beta 2 and TGF-beta 3 regulate fetal rat cranial suture morphogenesis by regulating rates of cell proliferation and apoptosis.

Cranial vault sutures are the major intramembranous bone growth sites during rapid expansion of the neurocranium. To function as bone growth sites, sutures need to remain patent, while allowing rapid bone formation at the edges of the bone fronts. Premature osseous obliteration of sutures (craniosynostosis) by fusion of bone fronts across the suture site prevents further bone formation at this site, often leading to severe facial dysmorphology. Although several growth factor receptor and transcription factor mutations have been implicated in craniosynostosis, the underlying mechanisms leading to sutural obliteration remain unclear. Previous studies have shown that dura secreted soluble factors responsible for maintaining suture patency and that suture fusion observed in the absence of dura was preceded by elevated levels of DNA synthesis and collagen production in the suture region. The use of neutralizing antibodies in a fetal calvarial culture model further demonstrated that removal of transforming growth factor (TGF) -beta 3 activity induced premature sutural obliteration, whereas removal of TGF-beta 2 activity prevented sutural obliteration. Data presented here demonstrate that suture obliteration induced by removal of TGF-beta 3 activity was preceded by elevated levels of DNA synthesis, similar to that seen upon removal of the dura. Addition of exogenous TGF-beta 3 to calvaria cultured without dura both prevented suture obliteration and reduced DNA synthesis to levels comparable to those seen with intact dura. Addition of exogenous TGF-beta 2 to calvarial cultures induced sutural fusion accompanied by elevated levels of cell proliferation. However, sutures rescued from obliteration by removal of TGF-beta 2 activity did not have decreased levels of cell proliferation, but rather appeared to be due to inhibited differentiation. In all calvaria in which sutures remained patent in culture, numbers of apoptotic cells were high within the suture, whereas in sutures destined to fuse, numbers of apoptotic cells were low. Results indicate that one of the critical regulators of suture patency is cell number. Alterations in cell number can trigger premature differentiation of cells, resulting in sutural obliteration. Furthermore, a complex interplay between closely related molecules is required to maintain cranial vault sutures in an unossified state, while allowing new bone to be formed at the edges of the bone fronts.

Animals↗
PubMed2004

Abrasion resistance of two types of nonabsorbable braided suture.

PURPOSE: The purpose of this study was to compare the abrasion resistance of different types of non-absorbable braided sutures under varying in vitro conditions of cyclic loading. TYPE OF STUDY: Biomechanical study. METHODS: Two types of nonabsorbable braided sutures were used in this study, No. 2 Ethibond and No. 2 Fiberwire, combined with 5 different anchors: 5.0-mm Corkscrew anchor, 5.0-mm BioCorkscrew anchor, 3.0-mm BioFastak anchor, Panalok RC anchor, and 3.5-mm Panalok anchor. Twelve tests for each construct were performed. A custom-designed testing apparatus was constructed to evaluate the abrasion resistance of sutures through an anchor eyelet. The apparatus cycled the suture through the anchor eyelet at a rate of 84 revolutions per minute and a speed of 12.5 m/min. In addition to suture type, the effect of different suture-to-anchor angles and testing conditions (dry v wet testing) were evaluated. The number of cycles to failure and the mode of failure were recorded (suture breakage v eyelet breakage). RESULTS: Results showed that under all testing conditions No. 2 Fiberwire displayed abrasion resistance superior to No. 2 Ethibond (P <.002 in all cases). The mean number of cycles to failure was 5 to 51 times greater when using No. 2 Fiberwire than when using No. 2 Ethibond. Altering the suture-to-anchor angle from 0 degree (in-line) to 45 degrees decreased the abrasion resistance of both No. 2 Ethibond (69.8 cycles +/- 26.5 cycles v 7.4 cycles +/- 3.9 cycles; P <.000004) and No. 2 Fiberwire (918.3 cycles +/- 417.4 cycles v 389.2 cycles +/- 195.7 cycles; P =.001) when using the 5.0-mm Corkscrew anchor. Fiberwire performed equally well under both dry and wet conditions (P >.05) whereas Ethibond performed better under wet conditions (P =.0002) when using the 5.0-mm BioCorkscrew anchor. When using the Panalok RC anchor (mean failure, 11.2 cycles +/- 1.3 cycles) or the 3.5-mm Panalok anchor (mean failure, 12.5 cycles +/- 2.4 cycles), constructs failed at significantly lower cycles than other comparable anchor-suture constructs (P <.00007 in all cases). In addition, although the vast majority of failure modes for the other anchor-suture constructs was by suture breakage, the Panalok RC anchor and 3.5-mm Panalok anchor consistently failed by cutting of the suture through the biodegradable eyelet. CONCLUSIONS: (1) Suture abrasion differs according to the suture type, anchor type, and testing conditions. (2) No. 2 Fiberwire showed superior resistance to abrasion when compared with No. 2 Ethibond under all conditions tested in the study. (3) The abrasion resistance of No. 2 Fiberwire is sufficiently high to eliminate, clinically, the theoretical concerns over weakening of suture from the anchor eyelet. (4) Suture eyelets formed of biodegradable materials can fail at low numbers of cycles by cutting of the suture through the biodegradable eyelet during cyclic loading. CLINICAL RELEVANCE: The study will help the surgeon to assess suture and suture anchor characteristics in order to optimize fixation of biologic tissues during surgical repair and reconstruction.

Biomechanical Phenomena↗
PubMed2006

Strength of damaged suture: an in vitro study.

PURPOSE: To determine the mechanical properties of damaged suture. METHODS: Undamaged and damaged sutures were tested by a single pull to failure. Sutures were damaged with a razor blade incorporated into a custom-designed jig. Sutures were tested to failure by straight pull and by pulling at 180 degrees through a suture anchor eyelet. The friction of sutures through anchors was also tested. RESULTS: For the straight line pull test, undamaged FiberWire (Arthrex, Naples, FL) had the highest load to failure (LTF) and ultimate tensile strength (UTS) of all sutures tested. Undamaged Orthocord (Mitek, Somerville, NJ) ranked second in both properties. Uncut polydioxanone (PDS) suture (Ethicon, Somerville, NJ) had a higher LTF and a comparable UTS with respect to Tevdek (Deknatel, Mansfield, MA) and Ethibond (Ethicon). For cut sutures, FiberWire and Orthocord had a significantly higher LTF and UTS than the other sutures tested. Suture stiffness was not significantly affected when the suture was cut. For the suture anchor test, FiberWire and Orthocord had the highest LTF, whether undamaged or damaged. When cut, PDS had the greatest loss of LTF and UTS during both tests. CONCLUSIONS: The newer polyethylene core sutures (FiberWire and Orthocord) have superior mechanical properties compared with other sutures. Their superior properties are maintained even when cut. Although uncut PDS had equivalent or superior strength compared with Ethibond and Tevdek, once cut, PDS suture was weakened significantly more compared with all other sutures tested. CLINICAL RELEVANCE: The mechanical properties of damaged suture are important to all surgeons who use suture arthroscopically.

Biomechanical Phenomena↗
PubMed2002

Transforming growth factor-beta3 (Tgf-beta3) down-regulates Tgf-beta3 receptor type I (Tbetar-I) during rescue of cranial sutures from osseous obliteration.

Appropriate biochemical regulation of intramembranous bone growth from sutures is necessary to achieve correct craniofacial morphology. Failure to form sutures (agenesis) or to maintain sutures in their unossified state (craniosynostosis) can result in severe facial dysmorphology. Several factors such as Twist, Msx2, fibroblast growth factors (Fgfs), bone morphogenetic proteins (Bmps) and transforming growth factors-beta (Tgf-betas) regulate suture patency, likely by interacting with one another. Tgf-beta2 and Tgf-beta3 use the same cell surface receptors, yet have opposite effects on suture patency, cellular proliferation and apoptosis within the suture. One possible mechanism by which Tgf-beta3 rescues sutures from obliteration is by regulating the ability of suture cells to respond to Tgf-beta2. As Tgf-beta3 does not regulate protein levels of Tgf-beta2 in sutures, Tgf-beta3 could regulate tissue responsiveness to Tgf-beta2 by regulating Tgf-beta2 access to receptors. Tgf-beta3 is a more potent competitor than Tgf-beta2 for cell surface receptors, so it is proposed that Tgf-beta3 binds to and down-regulates Tgf-beta receptor type I (Tbetar-I) expression by suture cells. This down-regulation would limit the ability of cells to respond to all Tgf-betas, including Tgf-beta2. To test this hypothesis, an in vitro culture model was used in which fetal rat sutures either remain patent or are induced to fuse when cultured in the presence or absence of dura mater, respectively. Tgf-beta3 was added to cultured calvaria and changes in the number of receptor positive cells within the suture were established. Data were compared with that seen in control sutures and in normal sutures in vivo. It was found that the numbers of cells expressing Tbetar-I within the suture matrix increased over time in sutures remaining patent. Osteoblastic cells lining the bone fronts on either side of sutures were Tbetar-I positive during early morphogenesis, but these numbers declined as sutures fused, both in vivo and in vitro. Addition of Tgf-beta3 to calvaria in culture decreased the number of Tbetar-I expressing cells in both fusing and non-fusing sutures, with dramatic decreases in the numbers of osteoblasts expressing Tbetar-I.

Activin Receptors, Type I↗
PubMedDate not supplied

Cyclic testing of meniscal sutures.

Suturing the meniscus has become a standard procedure for repairable tears. Studies investigating the outcome of meniscal sutures report a considerable rate of failures. Regarding the indications, which have been extended to the avascular zones, and regarding some accelerated rehabilitation protocols, the need for further in vitro investigations has become obvious. The aim of this study was to compare different meniscal suture types (vertical and horizontal mattress sutures) and materials (absorbable monofilament PDS 2-0, and nonabsorbable braided Ethibond 2-0 [Ethicon, Somerville, NJ]) under standard and cyclic loading conditions. Testing was performed on medial porcine menisci. In group A, specimens were tested to failure at a cross-head speed of 50 mm/minute. In group B, cyclic testing (100 cycles) was performed first within different load intervals (5 to 20 N and 5 to 40 N). Finally, the specimens were loaded until failure. In both groups, the failure loads were recorded and the failure modes were analyzed. In group A, there was no difference between suture type or suture material, with a mean failure load of 60 N. The failure modes were significantly different for vertical (100% suture failure) and horizontal sutures (50% suture failure) (P <.0001). In group B, 13% of the sutures failed under cyclic loading (7 with 40-N load, 1 with 20-N load). The gap of the sutured tear that appeared within the first load cycles was broader in horizontal sutures (P <.001). During the first cycles, the thread cut through the meniscus tissue and disappeared from the surface (partial tissue failure). There was no difference according to suture material. The ultimate failure loads after cyclic loading did not differ from the values of group A. These results show that meniscal sutures may fail under repetitive loading conditions and that a gap appears between the meniscal margins within the first loading cycles irrespective of the suture type and suture material used. The appearance of the gap and suture disappearance on the meniscal surface because of partial tissue failures (which were more pronounced in the horizontal sutures) confirmed the superior resistance of meniscal tissue to vertical sutures.

Animals↗
PubMed1997

Sonography of normal cranial sutures.

OBJECTIVE: The purpose of this study was to describe the normal sonographic appearance and measurement of normal major cranial sutures in neonates and infants. SUBJECTS AND METHODS: High-resolution sonograms of sagittal, coronal, and lambdoid sutures were obtained for two autopsy specimens and correlated with histologic sections obtained at identical locations. Also, 50 neonates and infants (0-5 months old [corrected age]) who had normally shaped craniums underwent sonography of the brain that produced normal findings. These neonates and infants also underwent sutural sonograms. The width and thickness of each of the major cranial sutures (sagittal, coronal, and lambdoid) were measured, with mean values established. Measurements were analyzed with paired t tests for interobserver variability. Linear regression was used for correlation of measurements with age. RESULTS: With a scan plane perpendicular to the suture line, sonograms revealed sutures as hypoechoic gaps between two hyperechoic bony plates. On sonograms, sagittal sutures had an end-to-end appearance instead of the beveled junction seen throughout most of the coronal and lambdoid sutures. In the 50 patients, sonograms revealed the mean width to be 0.89 +/- 0.35 mm (mean +/- SD) for coronal sutures. 0.93 +/- 0.28 mm for sagittal sutures, and 0.96 +/- 0.39 mm for lambdoid sutures. On sonograms, mean thickness was 1.97 +/- 0.54 mm for coronal sutures, 1.88 +/- 0.56 mm for sagittal sutures, and 2.49 +/- 0.86 mm for lambdoid sutures. We found no interobserver variability (p < or = .05). With linear regression analysis, we found no correlation between suture width or thickness and patient age (r = .01). CONCLUSION: In our study, high-resolution sonography proved to be a reliable and inexpensive technique capable of defining cranial sutures. Preliminary normative data obtained for cranial suture width and thickness showed no correlation with age in our population group. The normative data obtained will allow recognition of abnormal sutures, particularly synostotic or diastatic sutures.

Cranial Sutures↗
PubMedDate not supplied

"Tissue-drag" with polyglycolic acid (Dexon) and polyglactin 910 (Vicryl) sutures in strabismus surgery.

The new absorbable synthetic sutures, polyglycolic and (Dexon) and Polyglactin 910 (Vicryl), are excellent sutures for strabismus surgery, but they have a bothersome tendency to attract adjacent tissue (tissue-drag). This difficulty is found especially with the 5-0 size suture, less so with the 6-0 size suture, and minimally with the 7-0 size suture. The presence and number of short, stubbly, protuberant strands (hooklets) seen on the surface of these sutures under high magnification correlates with the lack of ease with which the sutures pass through tissue. Other factors involved in tissue-drag include the crevices between braids in these sutures and the fiber-tissue friction due to the innate nature of the suture materials. Sutures which pass with ease through tissue, such as catgut and nonabsorbable sutures, are seen to have smooth surfaces under high magnification. Coating the 5-0 and 6-0 Dexon and Vicryl sutures to smooth their surfaces and reduce tissue-drag was ineffective with isotonic saline solution, minimally to moderately effective with glycerine and with methylcellulose and polyvinyl alcohol solutions, but highly effective with peanut and sesame oils. Though tissue-passage of Dexon and Vicryl sutures was much improved by coating with oil and entirely satisfactory, it still was not quite as good as with catgut. Clinically, the oil did not compromise the knot security or ease of handling of the sutures. No unusual postoperative reaction was seen with the use of the oiled sutures. Although oiling the synthetic absorbable sutures at time of surgery is effective, we recommend that suture manufacturers reduce the tissue-drag of synthetic absorbable sutures either by smoothing the surface in the manufacturing process or by developing an absorbable coating applied to the sutures during manufacture.

Lubrication↗
PubMed1989

Quantitative evaluation of stiffness of commercial suture materials.

The bending stiffness of 22 commercial suture materials of varying size, chemical structure and physical form was quantitatively evaluated using a stiffness tester (Taber V-5, model 150B, Teledyne). The commercial sutures were Chromic catgut; Dexon (polyglycolic acid); Vicryl (polyglactin 910); PDS (polydioxanone); Maxon (polyglycolide-trimethylene carbonate); Silk (coated with silicone); Mersilene (polyester fiber); Tycron (polyester fiber); Ethibond (polyethylene terephthalate coated with polybutylene); Nurolon (nylon 66); Surgilon (nylon 66 coated with silicone); Ethilon (coated nylon 66), Prolene (polypropylene); Dermalene (polyethylene), and Gore-tex (polytetraflouroethylene). These are both natural and synthetic, absorbable and nonabsorbable and monofilament and multifilament sutures. All of these sutures were size 2-0, but Prolene sutures with sizes ranging from 1-0 to 9-0 were also tested to determine the effect of suture size on stiffness. The bending stiffness data obtained showed that a wide range of bending stiffness was observed among the 22 commercial sutures. The most flexible 2-0 suture was Gore-tex, followed by Dexon, Silk, Surgilon, Vicryl (uncoated), Tycron, Nurolon, Mersilene, Ethibond, Maxon, PDS, Ethilon, Prolene, Chromic catgut, coated Vicryl, and lastly, Dermalene. The large porous volume inherent in Gore-tex monofilament suture was the reason for its lowest flexural stiffness. Sutures with a braided structure were generally more flexible than those of a monofilament structure, irrespective of the chemical constituents. Coated sutures had significantly higher stiffness than the corresponding uncoated ones. This is particularly true when polymers rather than wax were used as the coating material. This increase in stiffness is attributable to the loss of mobility under bending force in the fibers and yarns that make up the sutures. An increase in the size of the suture significantly increased the stiffness, and the magnitude of increase depended on the chemical constituent of the suture. The flexural stiffness of sutures was also found to depend on the duration of bending in the test for stiffness. In general, monofilament sutures exhibited the largest time-dependent stiffness. This was most pronounced with the Gore-tex suture. Most braided sutures also showed less time-dependence in stiffness. Nylon sutures did not exhibit this time-dependent phenomenon regardless of physical form.

Elasticity↗
PubMed2004

Experimental studies in swine for measurement of suture extrusion.

The purpose of this scientific investigation was to identify the determinants of suture extrusion following subcuticular skin closure of dermal skin wounds. Miniature swine were used to develop a model for studying suture extrusion. Standard, full-thickness skin incisions were made on each leg and the abdomen. The wounds were closed with size 4/0 POLYSORB* or COATED VICRYL* sutures. Each incision was closed with five interrupted, subcuticular, vertical loops secured with a surgeon's knot. The loops were secured with 3-throw knots in one pig, 4-throw knots in the second pig, and 5-throw knots in the third pig. The swine model reproduced the human clinical experience and suture extrusion, wound dehiscence, stitch abscess, and granuloma formation were all observed. The cumulative incidence of suture extrusion over 5 weeks ranged from 10 to 33%. COATED VICRYL* sutures had a higher mean cumulative incidence of suture extrusion than that of POLYSORB* sutures (31% vs. 19%). With POLYSORB* sutures, the 5-throw surgeon's knots had a higher cumulative incidence of suture extrusion than the 3-throw or 4-throw surgeon's knot square, 30% vs. 17% and 10%, respectively. This swine model offers an opportunity to study the parameters that influence suture extrusion. Because the volume of suture material in the wound is obviously a critical determinant of suture extrusion, it is imperative that the surgeon construct a knot that fails by breakage, rather than by slippage with the least number of throws. Because both braided absorbable suture materials are constructed with a secure surgical knot that fails only by breakage rather than slippage with a 3-throw surgeon's knot square (2 = 1 = 1), the construction of additional throws with these sutures does not enhance the suture holding capacity but plays a key factor in precipitating suture extrusion. Finally, it is important to emphasize that the surgeon must always construct symmetrical surgical knots for dermal subcuticular skin closure in which the constructed knot is always positioned perpendicular to the linear wound incision. Asymmetrical knot construction for dermal wound closure becomes an obvious invitation for suture extrusion.

Animals↗
PubMed1996

The efficacy of a single continuous nylon suture for control of post keratoplasty astigmatism.

PURPOSE: Post operative adjustment of a single continuous suture is an effective means of reducing post keratoplasty astigmatism. This study evaluates post keratoplasty keratometry following suture adjustment with an adjusted suture in place and after the suture is removed. METHODS: Average keratometric astigmatism was measured over 24 months time in 26 patients with an adjusted continuous suture and 24 patients with a continuous suture that was not adjusted. Average keratometry in 43 patients with an adjusted continuous suture was compared with 37 patients with combined continuous and interrupted sutures. Finally, suture out astigmatism in 19 adjusted patients was compared to six patients with no adjustment. RESULTS: There was an increase in average corneal astigmatism over two years of 2.2 diopters in the adjusted group and 1.7 diopters in the non-adjusted group with sutures in place. One year following surgery, average keratometry flattened from 47.5 to 42.9 diopters in the adjusted continuous group and from 47.0 to 46.0 diopters in the group with combined continuous and interrupted sutures. Following suture removal, average astigmatism in patients who had suture adjustment was 4.4 diopters +/- 2.5 diopters (range 1-10 diopters), and 6.01 diopters (range 4-7) in the non-adjusted group. CONCLUSIONS: Average post keratoplasty astigmatism increases after a continuous suture is adjusted but the increase is comparable to patients with acceptable astigmatism who do not require adjustment. More progressive corneal flattening over 12 months time is seen with a continuous suture than which combined sutures. Average suture out astigmatism was 4.0 diopters following suture adjustment, compared to an average of 8.4 diopters prior to adjustment.

Astigmatism↗
PubMed1998

Trabeculectomy with releasable sutures: a prospective, randomized pilot study.

OBJECTIVE: To compare the short-term and long-term efficacy of using releasable sutures vs conventional interrupted sutures for scleral flap suturing in trabeculectomy. DESIGN: A prospective randomized study. SETTING: A university-affiliated referral eye hospital. PATIENTS: Thirty consecutive patients requiring trabeculectomy for uncontrolled primary glaucoma. INTERVENTION: Fifteen patients underwent trabeculectomy with permanent interrupted sutures; the same number underwent trabeculectomy with releasable sutures. MAIN OUTCOME MEASURES: Incidence of short-term shallowing of anterior chamber or hypotony and related complications, and long-term intraocular pressure control and bleb score. RESULTS: The mean percentage reduction in intraocular pressure on day 1 in the group with releasable sutures was 55.2%, while only a 0.8% reduction in anterior chamber depth was noted. This compared with figures of 59.3% and 10.1%, respectively, in the group without releasable sutures. Hypotony (intraocular pressure < or =6 mm Hg) was noted in 8 (53%) of cases without releasable sutures and 3 (20%) of cases with releasable sutures. Shallow anterior chamber (central anterior chamber depth, < or =1 mm) was noted in 5 (33%) of cases without releasable sutures and 1 (7%) of cases with releasable sutures. The mean +/- SD final bleb score was 5.4 +/- 0.3 in the group with releasable sutures compared with 4.2 +/- 0.6 in the group without releasable sutures (P<.001). The mean +/- SD final intraocular pressure at the end of 12 months was 16.9 +/- 1.2 mm Hg in the group without releasable sutures and 15.0 +/- 0.9 mm Hg in the group with releasable sutures (P<.001). Final intraocular pressure was controlled (intraocular pressure < or =21 mm Hg) in all patients in the group with releasable sutures, giving a success rate of 100%, and in 12 patients in the group without releasable sutures, giving a success rate of 80%. CONCLUSIONS: Use of releasable sutures is an effective way at no extra cost or instrumentation to maximize the long-term bleb score and lower intraocular pressure, and to minimize the short-term complications of trabeculectomy.

Anterior Chamber↗
PubMedDate not supplied

Comparative surgical and colonoscopic appearance of colon anastomoses constructed with sutures, staples, and the biofragmentable anastomotic ring.

UNLABELLED: The following animal study was undertaken to compare and assess the endoscopic gross appearance and histology of colonic anastomoses constructed with sutures, staples, and the biofragmentable anastomotic ring (BAR). METHODS: Three anastomoses--1 BAR, 1 stapled, and 1 sutured--were placed in each of 48 dogs and colonoscopy and anastomotic evaluation were done. RESULTS: No leaks were found by air insufflation at surgery. Grossly, the BAR had serosal hematomas in 27/48 anastomoses vs 7/48 for stapled and 1/48 for sutured (BAR vs stapled P < 0.0005 and sutured vs stapled P = 0.07). Adhesions were significantly greater for BAR (35/36) and sutured (34/36) compared to stapled (26/36) (BAR vs stapled P = 0.01 and sutured vs. stapled P = 0.04). Colonoscopic exams at days 3, 7, and 28 showed no significant difference among groups with respect to bleeding, ulceration, necrosis, granulation, or contour. Sutured anastomoses were more stenotic (24/31) than stapled (4/31) or BAR (3/31) ones (BAR vs sutured and sutured vs stapled P < 0.005). At 28 days, 10/10 sutured vs 2/10 stapled vs 3/10 BAR were stenotic (BAR vs sutured P = 0.02, sutured vs stapled P = 0.01). Inflammation on histologic exam at 28 days was not significantly different: sutured (12/12), stapled (12/12), or BAR (9/12). Fibrosis was more prominent in sutured (12/12) than in stapled (5/12) or BAR (4/12) anastomoses (BAR vs sutured P = 0.001, sutured vs stapled P = 0.004, and BAR vs stapled P = 1.00). All anastomoses healed primarily without necrosis or obstruction. CONCLUSIONS: (1) Colonoscopy to evaluate anastomoses can be done safely even in the early post-operative period. (2) The BAR anastomoses had the most serosal hematomas; BAR and sutured had more adhesions than stapled anastomoses; and sutured anastomoses had the most stenosis and fibrosis. None of these differences was of clinical significance.

Anastomosis, Surgical↗
PubMed1997

Effect of pulsatile pressure on the breaking strength and movement of Prolene sutures.

PURPOSE: Most studies of sutures used in vascular surgery have used steadily applied loads. But in vivo, sutures are subject to pulsatile pressures. Pulsatile pressures could weaken sutures, or they could be beneficial by helping to slide the suture, thereby equilibrating the tension between unevenly tightened loops. This study examined the effect of pulsatile pressures on the strength and movement of polypropylene (Prolene) sutures. METHODS: Segments of pig thoracic aorta were cannulated and studied in a tissue bath in vitro at 37 degrees C. A longitudinal arteriotomy was made and then closed with running 6-0 Prolene. Vessels were subjected to (1) no pressure; (2) 100 mm Hg steady pressure; or (3) 112/65 mm Hg pulsatile pressure. After 48 hours the sutures were studied for breaking strength. In a second, separate set of experiments, longitudinal arteriotomies were closed using running suture lines. These were constructed with either several loose loops or several overly tight loops. Fine wires were affixed to the suture loops to permit photographic recording of suture movement. RESULTS: There was no difference in breaking force among 68 sutures that had been subjected to (1) no pressure; (2) 100 mm Hg steady pressure; or (3) 112/65 mm Hg pulsatile pressure. These also were no different than sutures that were not sewn into arteries. These findings indicate that neither steady nor pulsatile pressures weaken Prolene sutures. In the second set of experiments, it was found that pulsatile pressure did cause movement of suture lines where there were loose loops (p < 0.05). However, neither steady nor pulsatile pressures caused movement of loops in suture lines that contained normal and overly tight loops. CONCLUSIONS: Neither steady nor pulsatile physiologic pressures weaken 6-0 Prolene sutures that have been used to close a longitudinal arteriotomy. These pressures can cause movement of loose suture lines, but do not equilibrate the tension between normal and overly tight suture loops. Overly tight loops may place excessive load on a suture line.

Blood Pressure↗
PubMed2002

Tgf-beta1, Tgf-beta2, Tgf-beta3 and Msx2 expression is elevated during frontonasal suture morphogenesis and during active postnatal facial growth.

OBJECTIVES: It is hypothesized that regulation of facial suture morphogenesis is similar to that of cranial sutures, with expression of similar regulatory molecules, governing suture formation and patency. The present study was designed to characterize the morphology of the frontonasal (FN) suture of the rat at different developmental stages and to investigate the presence and temporal-spatial expression of transforming growth factor-beta 1 (Tgf-beta1), Tgf-beta2, Tgf-beta3 and Msx2 mRNA within these structures. SETTING AND SAMPLE POPULATION: The Department of Biomedical Sciences at Texas A&M University System Health Science Center, Baylor College of Dentistry, Dallas, TX USA. Histological sections and RNA isolated from FN suture tissues of Sprague-Dawley rats, aged embryonic day 16 through postnatal day 20. METHOD: Sections were examined after immunohistochemical staining. Gene expression was determined by densitometric analysis of RT-PCR products run on agarose gels. RESULTS: FN sutures develop slightly later than cranial sutures and show increased complexity over time when compared to cranial sutures. FN sutures were closely associated with the nasal capsular cartilage, with intervening layers of perichondrium and periosteum. The pattern of expression of Tgf-betas within the FN suture tissues was similar to that seen in the cranial sutures. However, mRNA and protein of the Tgf-betas were differentially expressed over time compared to cranial sutures. In FN sutures, Tgf-beta mRNA levels were elevated both during the period of suture morphogenesis and during active bone growth from the suture in the early postnatal period. Msx2 mRNA expression was elevated in both the prenatal and postnatal periods, similar to Tgf-beta mRNA expression. CONCLUSION: Tgf-beta and Msx2 are present in facial sutures similar to cranial sutures, but are differentially expressed over time, perhaps reflecting different bone growth rates from these sutures.

Animals↗
PubMed2002

Adenovirus-mediated transmission of a dominant negative transforming growth factor-beta receptor inhibits in vitro mouse cranial suture fusion.

Recent studies have implicated the transforming growth factor (TGF)-beta family in the regulation of pathological sporadic cranial suture fusion. In addition, these studies have shown that TGF-beta is highly expressed by the dura mater underlying fusing murine cranial sutures. The purpose of the present experiments was to analyze the effects of disrupting TGF-beta signaling during programmed mouse cranial suture fusion. Using recombinant DNA technology, a replication-deficient adenovirus encoding a defective TGF-beta receptor (Ad.DN-TbetaRII) capable of blocking TGF-beta biological activity was constructed. Mouse posterior frontal sutures were harvested before the initiation of suture fusion (postnatal day 25), and the dura mater underlying the suture was infected with vehicle, Ad.DN-TbetaRII, or control virus (Ad.LacZ; n = 10 each). Sutures were cultured for 14 or 30 days in an organ culture system and analyzed macroscopically and histologically.X-gal staining of Ad.LacZ-infected sutures 14 days after culture revealed strong staining of cells localized to the dura mater. Macroscopic analysis revealed complete sutural fusion in vehicle and Ad.LacZ-infected sutures. In contrast, Ad.DN-TBRII-infected sutures demonstrated nearly complete patency. Histological analysis confirmed our macroscopic observations with sutural fusion in 81.3 +/- 10 percent and 74.5 +/- 9 percent of vehicle and Ad.LacZ-infected sutures, respectively, versus 38.1 +/- 12 percent (p < 0.001) in Ad.DN-TbetaRII-infected sutures. In addition, transfection with the Ad.DN-TbetaRII virus resulted in a significant attenuation of anterior-to-posterior suture fusion, with the majority of fused sections localized to anterior sections. These data strongly implicate TGF-beta biological activity in the dura mater underlying the posterior frontal suture in the regulation of programmed sutural fusion. In addition, this study demonstrates the utility of adenovirus-mediated gene transfer in preventing programmed sutural fusion.

Adenoviridae↗