Torsion of monofilament and polyfilament sutures under tension decreases suture strength and increases risk of suture fracture

[Surgical suture material-fundamentals]

At the end of surgical therapy, the access is closed with sutures. Surgical sutures are thus used to adapt wound edges and tissues. The task of the suture material is to hold the tissues together until healing. For patients, a cosmetically good suture is often the sign of good surgery. Different tissues and layers have different requirements regarding the suture material. The different types from monofil to polyfil, braided, from absorbable to nonabsorbable are presented. The classification of suture strengths is compared. The areas of application of different strengths and the duration until removal of the sutures for the different body regions are presented. The one-hand and two-hand techniques of surgical knots are explained in detail. The technique of suture removal is presented. In the online material, the suture materials of different composition and manufacturers can be compared.

Smart Design of Sensor-Coated Surgical Sutures for Bacterial Infection Monitoring

Virtually, all implantable medical devices are susceptible to infection. As the main healthcare issue concerning implantable devices is the elevated risk of infection, different strategies based on the coating or functionalization of biomedical devices with antiseptic agents or antibiotics are proposed. In this work, an alternative approach is presented, which consists of the functionalization of implantable medical devices with sensors capable of detecting infection at very early stages through continuous monitoring of the bacteria metabolism. This approach, which is implemented in surgical sutures as a representative case of implantable devices susceptible to bacteria colonization, is expected to minimize the risk of worsening the patient's clinical condition. More specifically, non-absorbable polypropylene/polyethylene (PP/PE) surgical sutures are functionalized with conducting polymers using a combination of low-pressure oxygen plasma, chemical oxidative polymerization, and anodic polymerization, to detect metabolites coming from bacteria respiration. Functionalized suture yarns are used for real-time monitoring of bacteria growth, demonstrating the potential of this strategy to fight against infections.

The Effect of Absorbable and Non-Absorbable Sutures on Nasal Width Following Cinch Sutures in Orthognathic Surgery

Background: Non-absorbable materials (nylon) are always used in cinch sutures to maintain nasal width and to improve harmonious facial symmetry in orthognathic surgery. However, a few drawbacks of nylon materials have been clinically reported following orthognathic surgery, such as nasal irritation and exposure of the sutures. An absorbable material (PDS) has been proposed in cinch sutures, not only to avoid the complications of nylon but also to stabilize the nasal width for a long-term follow-up. Methods: Fifty-seven patients with Angle’s malocclusion classification III receiving orthognathic surgery were enrolled in this study. A non-absorbable material (nylon) and an absorbable material (PDS) were utilized for the cinch sutures. Pre-operative (T1) and post-operative six-month (T2) craniofacial 3D images were collected for all patients to measure the alar curvature (Ac) width and the alar base (Al) width. A significance level of p < 0.05 was applied in the statistical analysis. Results: With the approval of IRB, cinch suturing was performed with nylon in 29 patients and with PDS in 28 patients. Pre-operative Ac and Al distances showed no significant difference between these two groups. There were also no significant differences between the suture materials in the peri-operative change in nasal width, including Ac (nylon: 1.999 ± 1.40; PDS: 1.484 ± 0.97; p = 0.112) and Al (nylon: 1.861 ± 1.66; PDS: 1.115 ± 0.92; p = 0.056). Conclusions: For cinch sutures in orthognathic surgery, PDS can maintain the peri-operative nasal width similarly to nylon; additionally, it can be absorbed in a timely manner without the drawbacks of non-absorbable materials.

Multifunctional Sutures with Temperature Sensing and Infection Control

The next-generation sutures should provide in situ monitoring of wound condition such as temperature while reducing surgical site infection during wound closure. In this study, functionalized nanodiamond (FND) and reduced graphene oxide (rGO) into biodegradable polycaprolactone (PCL) are incorporated to develop a new multifunctional suture with such capabilities. Incorporation of FND and rGO into PCL enhances its tensile strength by about 43% and toughness by 35%. The sutures show temperature sensing capability in the range of 25-40 °C based on the shift in zero-splitting frequency of the nitrogen-vacancy (NV^- ) centers in FND via optically detected magnetic resonance, paving the way for potential detection of infection or excessive inflammation in healing wounds. The suture surface readily coats with antibiotics to reduce bacterial infection risk to the wounds. The new suture thus is promising in monitoring and supporting wound closure.

Effect of Surgical Expertise on Biomechanical Properties of Sutures After Abdominal Wall Closure

BACKGROUND

Despite preventive methods and careful surgical technique, surgical site infection and incisional hernias are of main concern after the closure of surgical incisions and keep haunting abdominal wall wound healing. The aim of this study is to find how surgical expertise level modifies biomechanical properties of sutures commonly used in abdominal wall fascial closure (polypropylene, polyglactin 910, polydioxanone).

MATERIALS AND METHODS

Surgery residents with different experience levels performed abdominal wall fascial closure in swine models with the previously mentioned suture materials. A standardized technique was used. Sutures were removed, and a tensile stress test was performed on the removed sutures. A total of 81 abdominal fascial closures were achieved. Time, extension, maximum tensile force (F_tmax), and maximum stress were measured and analyzed.

RESULTS

The results of the polydioxanone stress test present a trend in three variables: extension, tensile force, and stress. The trend shows higher medians in the expert group and lower medians in the novice group. While using polypropylene sutures, medians in the expert group are the highest; however, a trend is not observed. Polyglactin 910 sutures have nonspecific behavior among the different experience groups and variables. Polypropylene is the material with the lowest F_tmax tested and fails at 42.64 (IQR 40.98-44.89) N. Regarding the elastic properties of the material, polyglactin demonstrates the least extension of all sutures tested, with a 14 (IQR 13.33-14.83) mm extension. This study demonstrates that polydioxanone has a superior F_tmax compared with polypropylene and has a superior extension at failure properties compared with polyglactin, confirming that polydioxanone could be the suture of choice used for abdominal wall fascial closure.

CONCLUSIONS

Study results do not show statistically significant differences regarding the impact of the experience level of different general surgery residents in the biomechanical properties of sutures used in abdominal wall fascial closure.

Positioning of the cross-stitch on the modified Kessler core tendon suture

Cryopreserved human tendons were sutured with different variations of a modified Kessler-type grasping suture in a series of different designs in order to assess the influence of the distance between the cross-stitch on the core suture (5 and 10 mm from the cut tendon edge) on the peripheral suture. An original mathematical model was employed to explain the mechanical behavior (strength, deformation, and distribution of load) of the different suture designs. The effect of the peripheral epitendinous suture, combined with the distance of the core suture, was evaluated. The variation of core suture distance had no relevant consequences on the overall resilience of the design. However, increasing the distance between the cross-stitches of the core suture reduces the deformation that is absorbed not only by the core suture itself but also by the peripheral suture. Adding a peripheral epitendinous suture to a 10-mm design almost doubles the breaking load in absolute values. The mathematical model predicts that the peripheral suture will support a greater load when the distance of the core suture cross-stitches is increased. The evidence level is II.

Delayed Wound Dehiscence of Anterior Knee Incisions in Patients Aged 20 Years and Younger: A Comparison of Subcutaneous Skin Closure

BACKGROUND

Delayed wound dehiscence (DWD) typically occurs 2 to 7 weeks postoperatively and is characterized by wound gapping and drainage at a surgical site which has initial normal wound healing. This wound problem clinically mimics deep surgical site infection and, after eventual skin healing, leaves a cosmetically unattractive widened, atrophic surgical scar.

METHODS

A single-center, retrospective analysis was completed of 252 knees, over a 13-year period, in 194 patients (average age, 14.9 y) undergoing patellar realignment surgery. All knees in this study were treated through an anterior midline knee incision from mid-patella to the tibial tubercle. At wound closure either a 2-0 polyglactin 910 (Vicryl) group (V) or polydioxane (PDS) group (P) suture was used for subcutaneous reapproximation and then the skin was closed with a 4-0 subcuticular Poliglecaprone 25 and IRGACARE (Monocryl) suture. Wound complications were recorded and analyzed by subcutaneous suture type, severity, size of involvement, duration, and treatment type.

RESULTS

Of the 252 knees, there were 132 knees in the V group and 120 in the P group. A total of 195 surgeries were primary surgeries and 57 knees were through previous surgical scars. Eleven patients had surgeries in which 1 knee was in each study group. Overall there were 6.1% (8/132) of the V group and 1.7% (2/120) of the P group with DWD (P=0.11); hence there was a trend toward more DWD with Vicryl than PDS, but this did not meet statistical significance. Mean time to resolution of wound dehiscence was 26 days for V group and 46 days for the P group. The length of incision was demonstrated to be a statistically significant independent risk factor for the development of DWD, irrespective of suture type.

CONCLUSIONS

The frequency of DWD in anterior knee incisions in our study population was 6.1% in the polyglactin 910 (Vicryl) group and 1.7% in the polydioxane (PDS) group. Although this analysis did not achieve statistical significance, a 3.5 times decrease in DWD when PDS was used is considered by the authors to be clinically significant. The authors have definitively switched from Vicryl to PDS for the subcutaneous skin closure at the knee in patients aged 20 years and younger in the push to make wound complications a nonevent.

LEVEL OF EVIDENCE

Level IV.

Surgical reconstruction of the urinary sphincter after traumatic longitudinal disruption

The question is whether the urethral sphincter may be reconstructed after longitudinal injury similar to anal sphincter injuries. Analogue to obstetric, anal sphincter repair, an approximation repair of the sphincter may be feasible. An overlap repair is possible in anal sphincter repair, but because of the little tissue available in the urethral sphincter this is not an option. We describe three cases of urethral sphincter injury of different aetiologies. All resulted in a total longitudinal disruption of the muscular components of the urethral sphincter complex. After making the diagnosis of urethral sphincter injury, a primary approximation repair was done. Follow-up of at least two and up to three years is promising with one male patient being completely continent and the two female patients needing one safety pad per day. Longitudinal disruption of the muscular elements of the sphincteric urethra may be primarily reconstructed with good success using an approximation technique with simple interrupted sutures.

The Miller׳s knot as an alternative to the surgical knotting? Characterization of the mechanical behavior

Several types of materials and surgical suture patterns are used in conventional surgery. Their combination with an appropriate knot is the basis for correct tissue apposition and healing. Knot security is essential to prevent loosening or slipping before the suture line is completely closed. Nevertheless, the knot itself is the weakest link in any surgical handling. The aim of this study is to determine and compare the mechanical behavior of four surgical knot types (square knot, surgeon׳s knot, square slipknot and Miller׳s knot) performed with three different suture materials (absorbable monofilament glyconate, non-absorbable monofilament polyamide and absorbable braided polyglycolic acid) in a non-biological experimental in vitro model (a tube of synthetic material with non-linear mechanical behavior). The mechanical properties of each suture material are also compared. Ten samples were mechanically tested for each suture and knot using a uniaxial tensile test until complete sample rupture. The failure Cauchy stress and stretch were calculated. The Cauchy stress at 5%, 10% and 15% strain and standard deviation were compared for each suture and knot type. The results demonstrated that all the suture materials had statistically significant differences in their non-linear mechanical behavior. Absorbable monofilament glyconate was the most compliant suture with the greatest tensile strength, while absorbable braided polyglycolic acid was the stiffest. Regardless of the suture type used, the Miller׳s knot had the greatest failure Cauchy stress and stretch, while the square, surgeon׳s and square slipknot had the lowest. In all cases, the Miller׳s knot was more compliant and had greater tensile strength than the other knots. The square knot, surgeon׳s knot, and square slipknot had statistically significant similarities in their mechanical behavior. Therefore, the Miller׳s knot could be classified as the gold standard and an alternative to the surgical knotting.