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PubMed1998

Studies in cranial suture biology: regional dura mater determines overlying suture biology.

The influence of dura mater on adjacent cranial sutures is significant. By better understanding the mechanisms of normal suture fusion and the role of the dura mater, it may be possible to delineate the events responsible for the premature suture fusion seen in craniosynostosis. In the Sprague-Dawley rat, the posterior frontal suture normally fuses between 12 and 20 days of postnatal life and has proved to be an excellent model to describe normal suture fusion. The purpose of this study was to document the critical role that the dura mater-suture complex may play on cranial suture biology. Forty Sprague-Dawley rats at 8 days of age were divided into two groups of 20 animals each. The control group (group A) had surgical disruption of the dura mater-calvarial interface. This was accomplished by elevating a strip of cranium inclusive of the posterior frontal and sagittal sutures and replacement of the cranial strip back to its anatomic position, all with the dura mater left intact. The experimental group (group B) had the same calvarial elevation (strip craniectomy), but the sutural anatomy/alignment was rotated 180 degrees. This rotation placed the posterior frontal suture into the sagittal suture's anatomic position and the sagittal suture into the posterior frontal suture's anatomic position. All of these procedures were accomplished by leaving the underlying dura mater intact. Animals were killed at 20, 30, 40, and 50 days (12, 22, 32, and 42 days postoperatively), and tissue sections were examined with hematoxylin and eosin staining. Group A (control) showed normal but delayed suture activity. The posterior frontal suture fused, and the sagittal suture remained patent. Fusion was delayed, not beginning before 20 days (12 days postoperative) and showing complete fusion between 30 and 40 days. Group B (180-degree calvarial rotation) demonstrated that the suture in the posterior frontal anatomic position (actual sagittal suture) fused between 20 and 40 days, whereas the suture in the sagittal anatomic position (actual posterior-frontal suture) remained patent throughout the study. This study demonstrates that the location of the dura mater-suture complex is important in determining either suture patency or closure in this model. Normal closure of the suture overlying the posterior frontal dura mater demonstrates that the dura mater itself, or forces derived in specific cranial locations, determines the overlying suture biology.

Animals↗
PubMed2003

The effect of suture anchor design and orientation on suture abrasion: An in vitro study.

PURPOSE: To evaluate the effects of suture anchor design and orientation on suture abrasion in a cyclic model. TYPE OF STUDY: In vitro. METHODS: Biomechanical studies have shown suture breakage to be a predominant mode of failure in a suture anchor repair construct. It is possible that suture abrasion during knot tying or in vivo cyclic loading may contribute to early failure. This study specifically investigates suture abrasion caused by 17 commonly used suture anchors and demonstrates the effects of suture anchor angulation and rotation on suture abrasion. To eliminate target tissue as a source of failure, all anchors were implanted into a solid block of sawbones material and tested with No. 2 Ethibond Excel sutures (Ethicon, Somerville, NJ). The testing model focused on 3 variables: suture anchor type, suture pull angle (SA) and angle of anchor rotation (RA). Abrasion testing was then performed on a servohydraulic materials testing system by continually cycling the suture back and forth through each anchor with an excursion of 4 cm at a rate of 0.5 Hz under a load of 10 N until suture failure occurred. RESULTS: Sutures performed significantly better when cycled in line with the anchor at 0 degrees SA with 0 degrees RA than they did at 45 degrees SA with 0 degrees RA or 45 degrees SA with 90 degrees RA. We found no significant difference between anchors tested at 45 degrees SA with 0 degrees RA and 45 degrees SA with 90 degrees RA. For tests performed using metallic suture anchors, all constructs failed by fraying of the suture. Constructs using biopolymer anchors and nonabsorbable polymeric anchors experienced a mixture of suture and anchor eyelet failures. CONCLUSIONS: In addition to the statistically significant detrimental effects of suture anchor angulation and rotation on suture abrasion, suture anchor eyelet design may also influence suture abrasion. Surgeons should be aware of the effects of anchor angulation, suture position in the eyelet, and design and composition of the eyelet to maximize the durability of the construct.

Biopolymers↗
PubMed1997

Studies in cranial suture biology: regional dura mater determines in vitro cranial suture fusion.

Craniosynostosis results in alterations in craniofacial growth that create cosmetic abnormalities and functional deficits, yet the biology underlying cranial suture fusion remains unknown. The purpose of the present study was to show that regional dura mater can induce suture fusion while in an organ culture system in cranial sutures programmed to remain patient. To accomplish this, we studied mouse cranial sutures, since in this model the posterior frontal suture (analogous to the human metopic suture) fuses in both in vivo and in vitro environments while all other sutures remain patent. We demonstrated that when mouse sagittal sutures (programmed to remain patent) were rotated or translocated to overlie the posterior frontal dura then grown in organ culture systems, suture fusion occurred. Twenty-four-day-old CD-1 mice (time when the posterior frontal suture was patent) were divided into three groups of 50 (n = 165: three groups of 50 cultured and three groups of 5 uncultured controls). Group A (unrotated control group) was characterized by a strip of posterior frontal and sagittal suture with underlying dural tissue grown in organ culture systems for up to 30 days and resulted in persistent patency of the sagittal suture and fusion of the posterior frontal suture in an anterior-to-posterior direction. Group B (rotated experimental group) was characterized by 180-degree suture rotation while in vitro and resulted in patency of the posterior frontal suture over the sagittal dura and fusion of the sagittal suture over the posterior frontal dura in a posterior-to-anterior suture direction. Group C (translocated experimental group) was characterized by translocation or shifting of sutures while in vitro and resulted in patency of the posterior frontal suture over the sagittal dura and fusion of the sagittal suture over the posterior frontal dura in an anterior-to-posterior suture direction. These data from the in vitro rotation and translocation experiments indicate that the "regional" posterior frontal dura determined in vitro cranial suture fusion. Molecular mechanisms behind this process are thought to involve inductive tissue interactions of the dural cells with the suture cells by means of growth factor-mediated signal pathways.

Animals↗
PubMed1997

Studies in cranial suture biology: Part I. Increased immunoreactivity for TGF-beta isoforms (beta 1, beta 2, and beta 3) during rat cranial suture fusion.

The mechanisms involved in normal cranial suture development and fusion as well as the pathophysiology of craniosynostosis, a premature fusion of the cranial sutures, are not well understood. Transforming growth factor-beta isoforms (TGF-beta 1, beta 2, and beta 3) are abundant in bone and stimulate calvarial bone formation when injected locally in vivo. To gain insight into the role of these factors in normal growth and development of cranial sutures and the possible etiology of premature cranial suture fusion, we examined the temporal and spatial expression of TGF-beta isoforms during normal cranial suture development in the rat. In the Sprague-Dawley rat, only the posterior frontal cranial suture undergoes fusion between 12 and 22 days of age, while all other cranial sutures remain patent. Therefore, immunohistochemical analysis of the fusing posterior frontal suture was compared with the patent sagittal suture at multiple time points from the fetus through adult. Whereas the intensity of immunostaining was the same in the posterior frontal and sagittal sutures in the fetal rat, there was increased immunoreactivity for TGF-beta isoforms in the actively fusing posterior frontal suture compared with the patent sagittal suture starting 2 days after birth and continuing until approximately 20 days. There were intensely immunoreactive osteoblasts present during fusion of the posterior frontal suture. In contrast, the patent sagittal suture was only slightly immunoreactive. A differential immunostaining pattern was observed among the TGF-beta isoforms; TGF-beta 2 was the most immunoreactive isoform and was also most strongly associated with osteoblasts adjacent to the dura and the margin of the fusing suture. Since the increased expression of TGF-beta 2 during suture fusion suggested a possible regulatory role, recombinant TGF-beta 2 was added directly to the posterior frontal and sagittal sutures in vivo to determine if suture fusion could be initiated. Exogenously added TGF-beta 2 stimulated fusion of the ectocranial surface of the posterior frontal suture. These data provide evidence for a regulatory role for these growth factors in cranial suture development and fusion. Additionally, the intense immunostaining for TGF-beta 2 in the dura mater underlying the fusing suture supports a role for the dura mater in suture fusion. It is possible that premature or excessive expression of these factors may be involved in the etiopathogenesis of craniosynostosis and that modulation of the growth factor profile at the suture site may have potential therapeutic value.

Animals↗
PubMed2000

Regional differentiation of cranial suture-associated dura mater in vivo and in vitro: implications for suture fusion and patency.

Despite its prevalence, the etiopathogenesis of craniosynostosis is poorly understood. To better understand the biomolecular events that occur when normal craniofacial growth development goes awry, we must first investigate the mechanisms of normal suture fusion. Murine models in which the posterior frontal (PF) suture undergoes programmed sutural fusion shortly after birth provide an ideal model to study these mechanisms. In previous studies, our group and others have shown that sutural fate (i.e., fusion vs. patency) is regulated by the dura mater (DM) directly underlying a cranial suture. These studies have led to the hypothesis that calvarial DM is regionally differentiated and that this differentiation guides the development of the overlying suture. To test this hypothesis, we evaluated the messenger RNA (mRNA) expression of osteogenic cytokines (transforming growth factor beta1 [TGF-beta1] and TGF-beta3) and bone-associated extracellular matrix (ECM) molecules (collagen I, collagen III, osteocalcin, and alkaline phosphatase) in freshly isolated, rat dural tissues associated with the PF (programmed to fuse) or sagittal (SAG; remains patent) sutures before histological evidence of sutural fusion (postnatal day 6 [N6]). In addition, osteocalcin protein expression and cellular proliferation were localized using immunohistochemical staining and 5-bromo-2'deoxyuridine (BrdU) incorporation, respectively. We showed that the expression of osteogenic cytokines and bone-associated ECM molecules is potently up-regulated in the DM associated with the PF suture. In addition, we showed that cellular proliferation in the DM associated with the fusing PF suture is significantly less than that found in the patent SAG suture just before the initiation of sutural fusion N6. Interestingly, no differences in cellular proliferation rates were noted in younger animals (embryonic day 18 [E18] and N2). To further analyze regional differentiation of cranial suture-associated dural cells, we established dural cell cultures from fusing and patent rat cranial sutures in N6 rats and evaluated the expression of osteogenic cytokines (TGF-beta1 and fibroblast growth factor 2 [FGF-2]) and collagen I. In addition, we analyzed cellular production of proliferating cell nuclear antigen (PCNA). These studies confirmed our in vivo findings and showed that dural cell cultures derived from the fusing PF suture expressed significantly greater amounts of TGF-beta1, FGF-2, and collagen I. In addition, similar to our in vivo findings, we showed that PF suture-derived dural cells produced significantly less PCNA than SAG suture-derived dural cells. Finally, coculture of dural cells with fetal rat calvarial osteoblastic cells (FRCs) revealed a statistically significant increase in proliferation (*p < 0.001) in FRCs cocultured with SAG suture-derived dural cells as compared with FRCs cocultured alone or with PF suture-derived dural cells. Taken together, these data strongly support the hypothesis that the calvarial DM is regionally differentiated resulting in the up-regulation of osteogenic cytokines and bone ECM molecules in the dural tissues underlying fusing but not patent cranial sutures. Alterations in cytokine expression may govern osteoblastic differentiation and ECM molecule deposition, thus regulating sutural fate. Elucidation of the biomolecular events that occur before normal cranial suture fusion in the rat may increase our understanding of the events that lead to premature cranial suture fusion.

Alkaline Phosphatase↗
PubMed2006

Mechanical and handling properties of braided polyblend polyethylene sutures in comparison to braided polyester and monofilament polydioxanone sutures.

PURPOSE: This study was designed to comprehensively compare the mechanical properties of 4 types of braided polyblend sutures with widely used braided polyester and monofilament polydioxanone sutures. METHODS: Polyblend polyethylene sutures (FiberWire [Arthrex, Naples, FL], Herculine [Linvatec, Largo, FL], Orthocord [DePuy Mitek, Raynham, MA], and Ultrabraid [Smith & Nephew Endoscopy, Andover, MA]), a braided polyester suture (Ethibond; Ethicon, Somerville, NJ), and an absorbable monofilament polydioxanone suture (PDS II; Ethicon), all USP No. 2, were mechanically tested. Fraying resistance was tested on eyelets of metallic and absorbable suture anchors. Cartilage abrasion caused by an intra-articularly placed suture knot was simulated by fraying on distal porcine femora. RESULTS: All polyblend sutures were stronger than Ethibond or PDS II sutures by at least a factor of 2, with or without a knot. When knotted, Herculine (261 +/- 44 N) was strongest, followed by Ultrabraid (244 +/- 3 N). FiberWire was most resistant against fraying on metallic anchors. Orthocord was by far least abrasive with absorbable anchors. Resistance to fraying was 100- to 500-fold (absorbable anchors) and 6- to 30-fold (metallic anchor) better for all polyblend sutures than for Ethibond. All braided sutures caused a similar amount of abrasion of joint cartilage, but they caused significantly more abrasion (>20-fold) than the monofilament degradable suture. CONCLUSIONS: The ultimate strength of polyblend suture material was 2- to 2.5-fold greater than that of polyester or polydioxanone sutures, but the resistance to fraying was up to 500-fold greater than that of polyester or polydioxanone sutures. With regard to strength, this makes polyblend sutures particularly advantageous for use with metallic edges of anchors or prostheses or with absorbable anchor eyelets. CLINICAL RELEVANCE: With a high resistance to fraying against metallic edges or a decrease in cutting of absorbable suture eyelets being up to 500-fold greater than with polyester or polydioxanone sutures, the new polyblend sutures appear to fill a void in the armamentarium of the surgeon, provided that at least 2 throws more than with conventional sutures are used for knot tying.

Animals↗
PubMed2004

TGF-beta1, FGF-2, and receptor mRNA expression in suture mesenchyme and dura versus underlying brain in fusing and nonfusing mouse cranial sutures.

Recent studies have supported a functional role for the transforming growth factor beta-1 (TGF-beta1) and fibro-blast growth factor 2 (FGF-2) signaling cascades in the process of mouse cranial suture fusion. TGF-beta1 and FGF-2 protein expression have been shown to be elevated in the fusing posterior frontal suture versus the nonfusing sagittal suture. The authors evaluated simultaneous mRNA expression of TGF-beta1 and its R1 receptor and FGF-2 and its R2 receptor during mouse cranial suture fusion. They evaluated the suture mesenchyme-dura complex separately from the underlying brain to determine whether there is tissue-specific biologic activity (i.e., brain versus suture mesenchyme-dura) for each cytokine and receptor. Data were collected from 150 male CD-1 mice studied over five time periods from postnatal days 22 to 45. They utilized reverse-transcriptase polymerase chain reaction as a means to detect TGF-beta1, TGF-beta receptor 1 (TGF-betaR1), FGF-2, and FGF receptor 2 (FGFR2) mRNA expression in mouse cranial tissues, beginning with the period of initiation of posterior frontal cranial suture fusion (postnatal day 22) and extending through completion of posterior frontal suture fusion (postnatal day 45). Expression of FGF-2 was significantly greater in posterior frontal suture mesenchyme and dura compared with sagittal suture mesenchyme and dura during the period of initiation of posterior frontal suture fusion, localizing this cytokine's expression to posterior frontal suture mesenchyme and dura during the process of cranial suture fusion. TGF-beta1 and FGFR2 mRNA expression was found to be up-regulated in posterior frontal suture mesenchyme and dura relative to the underlying brain tissue throughout the study period, whereas TGF-betaR1 and FGF-2 mRNA expression was significantly elevated relative to the underlying brain only at time points corresponding to the initiation of posterior frontal suture fusion (between postnatal days 22 and 31). These results indicate that there is tissue-specific mRNA expression of TGF-beta1, FGF-2, and their receptors between suture mesenchyme and dura and the underlying brain, which correlates with the period of posterior frontal suture fusion in the mouse model. Differences in gene expression between suture mesenchyme and dura relative to the underlying brain may be an important regulator of cranial suture biology. Understanding these differences may eventually help to identify possible targets and time windows by which to most effectively modulate cranial suture fusion.

Actins↗
PubMed2005

Laparoscopic suturing: effect of instrument handling on suture strength.

BACKGROUND AND PURPOSE: In open surgery, handling of suture at any position other than the end is discouraged because of evidence that handling deforms and weakens the material. The limited operative field of laparoscopic surgery necessitates repeated instrument handling of suture, and the effect of such handling has not been investigated. We assessed the effect of trauma imposed on various suture materials by laparoscopic needle holders and forceps. Also, the ideal suturing technique (interrupted v continuous) according to the physical characteristics of the suture material and the optimal length for laparoscopic sutures were determined. MATERIALS AND METHODS: Sutures of 2-0 and 3-0 polyglactin 910 and 2-0 poliglecaprone 25 were tested. Controlled damage was inflicted by grasping the suture for 1 second between the jaws of either toothed laparoscopic grasping forceps or a laparoscopic needle holder at a pressure of 45 MPa. Blind physical testing was then performed using a computer-controlled tensile testing system. The length and proportion of suture extension prior to breaking and the tensile strength were measured. Samples of undamaged and controlled damaged specimens, before and after breakage, were examined by scanning electron microscopy (SEM). RESULTS: The mean percentage extension in the control group was 46.3 mm for 3-0 Monocryl, 26.3 mm for 3-0 Vicryl, and 28.1 mm for 2-0 Vicryl. The mean tensile strengths were 47.9 N, 42.4 N, and 70.4 N for 3-0 Monocryl and 3-0 and 2-0 Vicryl, respectively. The 3-0 Monocryl and 3-0 Vicryl had significantly reduced tensile strength after damage compared with control sutures, whereas 3-0 Vicryl and 2-0 Vicryl had significantly impaired extension. After infliction of controlled damage with laparoscopic needle holders, the percent extension of damaged sutures was significantly less than that of undamaged sutures. Tensile strength was significantly lower for 3-0 Vicryl and 3-0 Monocryl after damage than before. The handling of Monocryl by laparoscopic needle holders and graspers produced punched-out defects and scratch marks, respectively. A number of damaged 2-0 and 3-0 Vicryl samples from the laparoscopic needle holder group showed disruption or unravelling of the braided filaments. CONCLUSION: We expect that our results underestimate the potential effect on suture strength and extension inflicted by laparoscopic suturing. The exact length of suture material cannot be recommended from the findings. However, interrupted sutures should be preferred, particularly for long suture lines. In addition, the findings support the use of laparoscopic graspers in preference to needle holders. The combination of a grasper in one hand and needle holder in the other is ideal. Finally, urologists initially embarking on laparoscopic reconstruction must take meticulous care in their suturing technique and, in particular, the number of times and force with which the suture is grasped.

Dioxanes↗
PubMedDate not supplied

Dura mater maintains rat cranial sutures in vitro by regulating suture cell proliferation and collagen production.

Craniosynostosis, the premature osseous obliteration of cranial vault sutures, can result from mutations in genes encoding components of growth factor signaling systems or the extracellular matrix (ECM). Little is known of the capacity of osteoprogenitor cells of the cranial sutures to divide or to synthesize ECM in situ. Osteoblasts derived from patients with prematurely fused sutures were reported to express alkaline phosphatase and osteocalcin at elevated levels, while proliferating at a rate comparable to control cells [DePollack et al., JBMR, 1996]; however, the suture osteoprogenitors, the population most likely to show proliferative abnormalities, were not present in the fused sutures used for this study. A model in which rat coronal sutures and associated bones develop normally in vitro, but in which sutures can be induced to fuse in the absence of dura mater, was used to examine cell proliferation and total protein synthesis in unfused sutures cultured in the presence of dura mater or in sutures induced to fuse in the absence of dura mater. Significantly increased cell proliferation was seen in suture cells prior to sutural obliteration, which returned to control levels as sutural fusion proceeded. Collagen synthesis in fusing sutures was elevated compared to non-fusing sutures and comparable to that seen in bone. Results indicated that in the absence of intercellular signals provided by the dura mater, suture cell proliferation increased initially, followed by increased synthesis of collagenous ECM within the suture and subsequent osseous obliteration of the suture. Thus factors originating in the dura mater affected suture cell proliferation and ECM production and were required for the maintenance of suture patency.

Animals↗
PubMed1993

Postkeratoplasty astigmatism with single running suture or interrupted sutures.

In a prospective randomized clinical trial we compared astigmatism after penetrating keratoplasty with two different suture techniques between two groups of patients (38 patients). The first group (18 patients) had a 24-bite single running 10-0 nylon suture (single running suture) with postoperative suture adjustment to decrease astigmatism. The second group (20 patients) had a combination of a 16-bite running 10-0 nylon suture and eight interrupted 10-0 nylon sutures (combined running and interrupted sutures) with selective postoperative removal of interrupted sutures to decrease astigmatism. The single running suture resulted in a lower postoperative astigmatism than a combined running and interrupted suture technique (single running suture, 2.7 +/- 2.2 diopters; combined running and interrupted sutures, 3.9 +/- 2.5 diopters; P < .02). Average length of follow-up was similar in both groups (single running suture, 9.0 +/- 2.2 months and combined running and interrupted sutures, 8.4 +/- 2.2 months). Minimal length of follow-up was six months in both groups. No running sutures were broken. The adjustable single running suture technique provided greater control of astigmatism after penetrating keratoplasty than a technique using a combination of a 16-bite running suture and eight interrupted sutures.

Adult↗
PubMed1995

Randomized clinical trial of penetrating keratoplasty. Before and after suture removal comparison of intraoperative and postoperative suture adjustment.

PURPOSE: The authors performed a prospective, randomized clinical trial of penetrating keratoplasty and compared visual acuity, refraction, and topography up to 15 months postoperatively (3 months after suture removal) after intraoperative and postoperative suture adjustment. METHODS: Twenty-five patients undergoing penetrating keratoplasty for avascular corneal pathology were randomly assigned to two groups. All surgery was done by one surgeon using the same technique (except for intraoperative suture adjustment) with suction trephination (8 mm) and a running 10-0 nylon suture. Intraoperative suture adjustment was performed in the test group and was not performed in the control group. Postoperative suture adjustment was done during the first postoperative month and up to 4 months postoperatively in all patients who had more than 3.5 diopters (D) of astigmatism. The running suture was removed at approximately 12 months postoperatively. Refraction and computed topographic analysis to compare patients with intraoperative and postoperative suture adjustment were performed at 1, 3, 6, 9, 12 (before suture removal), and 15 (after suture removal) months. RESULTS: There was less (P = 0.004) topographic astigmatism up to 12 months postoperatively (pre-suture removal) in patients adjusted intraoperatively (mean +/- standard deviation, 1.53 +/- 0.72 D) than in patients adjusted postoperatively (2.83 +/- 1.19 D). After suture removal, at 15 months postoperatively, astigmatism was still less in the intraoperative adjustment group (1.75 +/- 1.04 D) than in the postoperative adjustment group (2.23 +/- 17.2 D), but the authors could not demonstrate statistical significance. After intraoperative adjustment, no significant change in mean astigmatism occurred, and no patient had more than a 1.18-D change in the amount of astigmatism or more than a 22 degrees change in axis (75% < 10 degrees change) after suture removal. Corneas were more regular until suture removal in the group with intraoperative adjustment, but differences decreased after suture removal. Best spectacle-corrected visual acuity was better in the intraoperatively adjusted group until suture removal with no significant changes in best spectacle-corrected visual acuity between 1 and 15 months. Best spectacle-corrected visual acuity improved more slowly after postoperative adjustment and was different at 1 and 15 months (P = 0.0005). CONCLUSION: The authors demonstrated low astigmatism and good visual results at 15 months postoperatively after either intraoperative or postoperative running suture adjustment, but intraoperative suture adjustment permitted more rapid visual rehabilitation, increased safety, and increased refractive stability.

Astigmatism↗
PubMedDate not supplied

Failure of suture material at suture anchor eyelets.

PURPOSE: In the repair of soft tissue to bone using suture anchors, failure of the suture material can occur at the anchor eyelet. This study examines the load strength at which suture material fails with different metallic suture anchor eyelets. TYPE OF STUDY: Biomechanical study. METHODS: Suture material (Ethibond No. 2, Ethicon, Norderstedt, Germany) was pulled out from 22 metallic suture anchor models at 60 mm/min, and tensile load at failure and failure mode were recorded. Tests were performed either by simultaneous pulling on 2 suture limbs in 3 different directions (straight, at 45 degrees, and at 45 degrees rotated by 90 degrees to the suture anchor axis) or by pulling on 1 suture limb while measuring the resulting force on the second limb. All tests were performed until suture failure. Pulling was performed in single tests on an Instron materials testing machine (High Wycombe, UK), with the anchors held by a vise. RESULTS: In all cases, the suture failed at the anchor eyelet. Failure load at straight loading ranged from 116 +/- 5 N to 226 +/- 5 N and from 69 +/- 5 N to 193 +/- 7 N when loaded at an angle of 45 degrees. The best results were found with the Statak 5.2-mm (Zimmer, Warsaw, IN): 177 N; Corkscrew 6.5-mm anchor (Arthrex, Naples, FL): 174 N; and PeBA 4.0-mm anchor (OBL Orthopaedic Biosystems, Scottsdale, AZ): 169 N. With each eyelet, sutures failed preferentially in 1 direction, depending on the presence of sharp edges. CONCLUSIONS: Suture material can be cut at suture anchor eyelets. Failure load depends on sharp edges on the eyelet and occurs at forces up to 73% below the breaking strength of the suture material on a smooth hook. Anchors with suture-protecting channels are particularly sensitive to the orientation in which the sutures are loaded.

Equipment Design↗
PubMed2006

The suture-weave technique: a method of reloading a deployed unloaded suture anchor.

Many suture anchors hold 2 sutures per anchor. Occasionally during a procedure, 1 of these sutures may be inadvertently pulled out of the anchor eyelet. We describe the technique of rethreading a deployed suture anchor in the event that 1 of the sutures is inadvertently unloaded from the anchor eyelet. We have evaluated its effectiveness in vivo. The basic steps of the "suture-weave" technique are as follows. If 1 strand remains threaded through the anchor eyelet, it is tensioned so that there is 1 long end and 1 short end. The free suture is threaded into the eye of a graft preparation needle and this needle is then used to pierce the braids of the long end of the threaded suture. The free suture is interwoven through the braids of the threaded suture. The short end of the threaded suture is then pulled while visualizing the anchor eyelet arthroscopically. The free suture passes through the eyelet as the intersection of the 2 woven sutures traverses the eyelet. During this process, 3 suture strands are traversing the eyelet. Finally, the intersecting suture limbs are pulled free from each other such that there are 2 separate suture strands that slide independently and pass through the anchor eyelet once again. This procedure has been successfully used in vivo without complications. It is important to note that this procedure will only work in an anchor eyelet that will allow for the passage of 3 suture strands.

Arthroscopy↗
PubMed1996

Studies in cranial suture biology: IV. Temporal sequence of posterior frontal cranial suture fusion in the mouse.

The biology underlying normal and premature cranial suture fusion remains unknown. To develop a model for normal cranial suture fusion, the temporal sequence of the posterior frontal cranial suture fusion in the mouse was determined. To do this, all the cranial sutures of three distinct strains of mice (CD-1, CF-1, and C57bl-6) were studied histologically for fusion at sequential time points. Two studies were set up using group A mice (n = 72, all sutures studied) and group B mice (n = 78, only the posterior frontal suture studied, but more precisely along its anatomic length). In the group A cranial suture study, mice were sacrificed starting at newborn age and then every 5 days until age 50 days. In addition, two mature mice (250 days old) from each strain were sacrificed. In all three mouse strains, histologic examinations showed that the anterior frontal, sagittal, coronal, lambdoid, and occipitointerparietal sutures remained patent at up to 50 days of age and were patent in the 250-day mature mice. However, examination of the midpoint of the posterior frontal suture showed patency at 30 days, partial fusion at 35 days, and complete fusion by 40 days. These data prompted the posterior frontal suture fusion study. In the group B posterior frontal suture fusion study, mice were sacrificed at age 23 days and then every 2 days until 47 days of age. The anterior, midpoint, and posterior aspects of the posterior frontal suture were examined: The anterior aspect fused between 25 and 29 days; the midpoint fused between 31 and 37 days; and the posterior aspect fused between 39 and 45 days. These data indicate that fusion of the posterior frontal cranial suture in the mouse proceeds in a defined temporal sequence from an anterior to posterior direction in three distinct strains of mice, while in the same mice all other cranial sutures remain patent. By describing and understanding the fusion of the normal posterior frontal suture, a biologic basis of normal suture development and fusion can be established and used as a comparison for murine cranial sutures altered surgically, biochemically (with growth factors), or genetically (with craniosynostotic phenotypes).

Animals↗
PubMed2001

Correction of coronal suture synostosis using suture and dura mater allografts in rabbits with familial craniosynostosis.

OBJECTIVE: Resynostosis following surgical correction of craniosynostosis is a common clinical correlate. Recent studies suggest that the dura mater is necessary to maintain suture patency. It has also been hypothesized that dura mater from synostotic individuals may provide aberrant biochemical signals to the osteogenic fronts of the calvaria, which result in premature suture fusion and subsequent resynostosis following surgery. This study was designed to test this hypothesis by surgically manipulating the coronal suture and dura mater in rabbits with familial craniosynostosis to prevent postsurgical resynostosis. DESIGN: Craniofacial growth and histomorphometric data were collected from 129 rabbits: 72 normal controls and 57 rabbits with bilateral coronal suture synostosis (15 unoperated on controls; 13 surgical controls; 9 dura mater transplant only; 10 suture transplant only; and 10 suture and dura mater transplant). At 10 days of age, all rabbits had radiopaque amalgam markers placed on either side of the coronal, frontonasal, and anterior lambdoidal sutures. At 25 days of age, 42 synostosed rabbits had a 3 to 5-mm wide coronal suturectomy. Coronal sutures and/or underlying dura mater allografts were harvested from same-aged, wild-type, isohistogenic control rabbits and transplanted onto the dura mater of synostosed host rabbits. Serial radiographs were taken at 10, 25, 42, and 84 days of age, and the suturectomy sites were harvested at 84 days of age in 44 rabbits and serially sectioned for histomorphometric examination. RESULTS: Results revealed that cranial vault growth was significantly (p < .05) improved following surgical release of the fused coronal suture compared with synostosed rabbits who were not operated on but was still significantly different (p < .05) from that of normal control rabbits. By 84 days of age, significant (p < .05) differences were noted in calvarial suture marker separation, cranial vault shape indices, and cranial base angles between rabbits with and without dura mater allografts, probably as a result of resynostosis of the suturectomy site or suture-only allografts. Qualitative histological examination revealed that at 84 days of age rabbits with suture and dura allografts had patent coronal sutures, suture-only allografts had fused coronal sutures with extensive endosteal hyperostosis, dura mater-only allografts had some new bone in the suturectomy site that resembled rudimentary osteogenic fronts, and suturectomy controls had extensive endosteal bone formation and resynostosis of the suturectomy site. Significantly (p < .05) more bone was found in the suturectomy sites of rabbits without dura mater allografts compared with rabbits with dura mater allografts. CONCLUSIONS: Results support the initial hypothesis that normal dura mater allografts will maintain suture or suturectomy site patency and allow unrestricted craniofacial growth. However, it is still unclear whether the dura mater from normal rabbits was providing biochemical signals to the transplanted sutures or suturectomy sites or simply acting as a barrier to prevent abnormal biochemical signals from the dura mater of synostosed rabbits from reaching the calvaria. The clinical and therapeutic implications of these procedures are discussed.

Analysis of Variance↗
PubMed1988

Growth of the aortic anastomosis in pigs. Comparison of continuous absorbable suture with nonabsorbable suture.

Growth at the anastomotic site after continuous vascular anastomosis in the pediatric patient remains a problem. Primary end-to-end anastomosis of the infrarenal aorta was performed with absorbable Maxon suture or nonabsorbable Prolene suture in 20 piglets. Ten of the Maxon suture group and nine of the Prolene suture group survived; one pig died of infection. The animals were put to death 6 months after the operation. Each abdominal aorta was removed and a roentgenogram was obtained. The aorta was then burst-tested to 300 mm Hg, measured, and examined both grossly and histologically. All anastomoses were patent and no burst failures were observed in either group. However, Prolene sutures protruded into lumen and were partially embedded in the aortic wall in all animals in the Prolene suture group. Thrombus adhered to the intraluminal Prolene suture in six of nine animals. The growth of the anastomotic area was wider in the Maxon suture group (446.4% +/- 131.8% versus 317.6% +/- 121.5%, p less than 0.05). Stenosis was more common in the Prolene suture group (7/9) than in the Maxon suture group (1/10) (p less than 0.01), but the distal segment was widely patent in both groups. Dilatation at the anastomotic site was present in eight of 10 pigs in the Maxon suture group and in two of nine in the Prolene suture group. Histologic study showed that the area of tissue reaction was more prominent in the Prolene suture group. No sutures were observed in the Maxon suture group. We therefore recommend the use of absorbable Maxon sutures for anastomoses in which the suture line must be able to grow.

Absorption↗
PubMed2001

[Effect of various suture strength factors on behavior of meniscus sutures in cyclic loading conditions].

The aim of this study was to analyze meniscal sutures under cyclic loading conditions for different suture types (vertical and horizontal mattress sutures) and suture materials (absorbable monofilament sutures: PDS 2-0; PDS-0, and PDS-1 USP). Testing was performed on medial porcine menisci, using a well-established biomechanical testing model with a complete longitudinal tear 3 mm from the periphery of the meniscus. Sixty specimens were used. One suture was tested at a time. During cyclic testing 100 load cycles were applied with a crosshead speed of 50 mm/min. Three different maximum loads (10 N, 20 N, and 40 N) were used. The preload was set at 5 N. After cyclic loading, the specimens were loaded until failure. During cyclic loading, a gap appeared between the two parts of the meniscus, and partial tissue failures were observed at the surface of the meniscus. Gapping was more marked with higher loads and with the weaker suture material (p < 0.001). Using PDS 0 and PDS 1 sutures, less partial tissue failures were observed compared to PDS 2-0 (p < 0.001). The ultimate failure loads after cyclic loading were higher with PDS-0 and PDS-1 sutures. With these suture materials vertical sutures were stronger than horizontal sutures (p < 0.05). Using PDS 2-0 this difference could not be found. These results show that the primary strength of meniscal sutures depends on the suture material. The frequency and the amount of gapping and partial tissue failures, which can be observed under cyclic loading, are less distinct with PDS-0 and PDS-1 compared to PDS 2-0. From a biomechanical point of view, PDS 0 and PDS 1 sutures are recommended for meniscal sutures to guarantee a high primary stability, a small amount of gapping, and few partial tissue failures.

Animals↗
PubMed1995

Normal sutural fusion and the etiology of single sutural craniosynostosis: the microspicule hypothesis.

Single sutural craniosynostosis is a disorder wherein a calvarial suture fuses prematurely, resulting in an abnormally shaped head. Children afflicted are normal neurologically, and the bone bridging the sutures is normal histologically. The mechanism of normal or pathologic sutural fusion is unknown. These facts prompted the authors to reexamine normal sutural anatomy and the concepts of skull growth in an animal model. Histochemical staining to identify osteoblasts and osteoclasts and tetracycline labeling were performed on neonatal rabbit calvarial sutures. Osteoblasts are found on all bony surfaces including the sutural edges, but do not extend across the sutural space. Thus the periosteum per se does not bridge the suture. Osteoclasts are found only in the diploic space. Thus, there is no mechanism to remove bone at/or within the suture. Tetracycline labeling revealed immense bone production at the suture as compared with dural and periosteal surfaces. Microscopic spicules of bone bridging the suture were identified. Based upon the above observations, we propose a new hypothesis for the mechanism of normal and pathologic sutural fusion. Bony microspicules normally and intermittently form and bridge the suture. As there is no mechanism to remove these spicules, we propose that normal mechanical forces cause them to fracture. A spicule that fails to fracture functions as a scaffold, upon which more bone is deposited, resulting in sutural fusion. Single sutural craniosynostosis results when a normal process occurs prematurely.

Animals↗