Comprehensive Guide to Knot Tying and Suturing Techniques
Core Principle: Sutures Are the Gold Standard
For most surgical wound closures, sutures remain the first-line method, particularly when wound integrity and mechanical support are critical priorities. 1 Tissue adhesives carry a significantly higher risk of wound breakdown (RR 3.35; 95% CI 1.53-7.33), meaning you must treat 43 patients with sutures instead of glue to prevent one additional dehiscence. 1
Fundamental Suturing Techniques
Continuous Subcuticular Suturing
- Primary technique for most closures: This method significantly reduces superficial wound dehiscence (RR 0.08; 95% CI 0.02-0.35) compared to interrupted sutures. 1, 2
- Indications: All wounds requiring extended mechanical support, cosmetically sensitive areas, and any closure where dehiscence risk must be minimized. 1
- Advantages: Superior wound edge approximation, reduced dehiscence rates, and comparable cosmetic outcomes to interrupted sutures with adhesive strips. 3
- Disadvantages: Requires more technical skill than interrupted sutures, particularly in laparoscopic settings. 4
Interrupted Suturing
- Secondary technique: Use when continuous suturing is technically difficult or when individual suture removal may be needed. 1
- Indications: Contaminated wounds where selective suture removal may be necessary, areas requiring differential tension adjustment. 4
- Disadvantages: Higher superficial wound dehiscence rates compared to continuous subcuticular technique. 1
Single-Layer Anastomotic Technique
- Specific for biliary and vascular reconstruction: Follow principles of single-layer stitching with uniform margins, appropriate density, and moderate knotting strength. 4
- Technical specifications: Use 6-0 fine suture needle for thin-walled structures; 5-0 or 6-0 for thicker tissues like choledochojejunostomy. 4
- Critical principle: Anastomosis must be tight enough to prevent leakage but not so tight that it damages blood supply to anastomotic tissues. 4
Suture Material Selection
Slowly Absorbable Monofilament Sutures (Preferred)
- Primary choice: 4-0 poliglecaprone or 4-0 polyglactin retain 50-75% tensile strength after 1 week. 1, 2
- Indications: All standard wound closures, particularly those requiring extended support during healing. 1
- Advantages: Reduced bacterial seeding compared to braided materials, predictable absorption profile. 2
- Contraindications: Rapidly absorbable sutures increase incisional hernia rates and should be avoided. 1
Triclosan-Coated Antimicrobial Sutures
- Mandatory for high-risk wounds: Use in contaminated or infection-prone wounds; reduces surgical site infection risk (OR 0.72; 95% CI 0.59-0.88). 1, 2, 3
- Indications: Any wound with contamination, diabetes, immunosuppression, or other infection risk factors. 1
Polytetrafluoroethylene (PTFE) Sutures
- Robotic surgery preference: More easily tied with robotic instruments or knot pushers than polypropylene. 4
- Specific use: Left atrial closure in cardiac surgery, valve repair procedures. 4
Material to Avoid
- Non-absorbable sutures in body cavities: Leaving non-absorbable lines in cavities should be avoided due to infection and foreign body reaction risk. 4
- Braided sutures for conjunctival closure: Nylon monofilament preferred over Mersilene polyester to reduce erosion risk. 4
Knot Tying Techniques
Intracorporeal Knot Tying (ICKT)
Slipping Knot Technique (Superior Quality)
- Primary laparoscopic technique: Demonstrates superior knot quality compared to surgical square knot in all skill levels. 5
- Indications: Laparoscopic procedures requiring suture placement under tension, including Nissen fundoplication. 5
- Advantages: Better knot quality, similar performance time to square knot after training, easier to achieve secure closure under tension. 5
- Technical execution: Form loop extracorporeally, pull one end to slip knot into position without knot pusher. 6, 7
Surgical Square Knot
- Traditional technique: Standard for open surgery, acceptable for laparoscopic use but inferior quality to slipping knot. 5
- Disadvantages: Lower knot quality under tension, requires more experience to execute properly. 5
- Variability concern: High variability exists among surgeons (only 19.8% perform identical technique), suggesting need for standardization. 8
Modified "Indian Rope Trick" Technique
- Simplified laparoscopic method: Provides extracorporeal control of one suture limb via percutaneous placement. 6
- Indications: Retroperitoneal and transperitoneal procedures including pyeloplasty, ureterolithotomy, varicocelectomy. 6
- Advantages: Easier to learn than conventional laparoscopic suturing, eliminates need for knot pusher for extracorporeal knots. 6
Easy Slip-Knot for Deep Sutures
- Endoscopic specialty technique: Developed for narrow working spaces in transsphenoidal surgery. 7
- Indications: Deep operative fields with limited access, endoscopic procedures. 7
- Advantages: Knot naturally slips into position without pusher, secures sutures reliably in confined spaces. 7
Extracorporeal Knot Tying
- Alternative laparoscopic method: Comparable time to intracorporeal technique but requires knot pusher. 9
- Indications: When intracorporeal technique is too difficult or surgeon lacks proficiency. 9
- Disadvantages: No significant time advantage over intracorporeal method for experienced surgeons. 9
Mechanical Assist Devices (Quik-Stitch)
- Time-saving option: Reduces knot tying time by 30-51% depending on surgeon experience. 9
- Greatest benefit: Less experienced surgeons and trainees benefit most (average time 92.5-128.7 seconds vs 224.3-265.3 seconds for manual techniques). 9
- Indications: Training environments, procedures where time reduction is critical. 9
Autoknotting Devices
- Robotic surgery application: Greatly reduces complexity and increases speed compared to manual robotic knot tying. 4
- Specific use: Securing braided annuloplasty ring sutures in mitral valve procedures, may shorten cross-clamp times. 4
Critical Technical Principles
Suture-to-Wound Length Ratio
- Mandatory ratio: Maintain at least 4:1 ratio to minimize incisional hernia and wound complications. 1
- Application: Particularly critical in emergency laparotomy and abdominal wall closures. 1
Knot Tying Fundamentals
- Standard technique components: Cross both thread ends at beginning (62.5% of surgeons do this), perform at least two identical throws with same standing part (75.5% compliance), change standing part for security (45.3% compliance). 8
- Tension management: Moderate knotting strength prevents both loosening and tissue strangulation. 4
- Common pitfall: Continuous tightly pulled sutures can strangulate wound edges, compromising healing. 3
Mattress Sutures for Sclerotomy Closure
- Specific technique: Long scleral passes increase vector forces in re-apposing wound edges. 4
- Critical detail: Wound must be dried and thoroughly checked for leakage; do not assume small oozing will resolve spontaneously. 4
- Knot placement: Rotate knots posteriorly underneath suture tabs with long tails for lower profile and decreased erosion risk. 4
Procedure-Specific Applications
Laparoscopic Partial Nephrectomy
- Pledget clip technique: Pre-prepare 9-inch No. 0 polyglactin suture with knot 2-3 inches from end, place Hem-o-lok clip proximal to knot. 4
- Execution: Pass through renal parenchyma, pull pledgeted clip flush against capsule, pass over rolled oxidized cellulose bolster, secure with second clip, then tie free ends. 4
- Advantages: Securely maintains hemostatic compression, decreases risk of suture tearing through renal capsule during knot tying. 4
Robotic Mitral Valve Surgery
- Suture management: Use longitudinal suture guide inferior and lateral to working port, place sutures left to right starting at left trigone moving counter-clockwise. 4
- Material preference: PTFE suture preferred over polypropylene for easier robotic manipulation. 4
- Autoknotting advantage: Reduces complexity and increases speed for securing valve sutures. 4
Biliary Reconstruction
- Mucosal-mucosal anastomosis: Use non-invasive suture needle for intermittent or continuous technique. 4
- Size selection: 6-0 for thin bile ducts, 5-0 or 6-0 for choledochojejunostomy based on wall thickness. 4
- Drainage consideration: Not routinely necessary; only place for unsatisfied anastomosis, inflammation, or stones, remove within 3 months. 4
Absolute Contraindications
When Sutures Are Mandatory (Never Use Adhesives)
- High-tension wounds: Tissue adhesives fail where mechanical forces are significant. 1
- Emergency laparotomy/abdominal wall closures: Require proper suture technique with appropriate ratios and materials. 1
- Compromised wound integrity: When dehiscence risk is elevated, sutures are significantly superior. 3
Technique-Specific Contraindications
- Rapidly absorbable sutures: Contraindicated for fascial closure due to increased hernia rates. 1
- Braided sutures in cavities: Avoid due to bacterial seeding risk; use monofilament. 2
- Excessive tension: Avoid over-tightening anastomoses as this damages blood supply. 4
Training and Skill Acquisition
Learning Curve Data
- 3-hour hands-on training: Improves all parameters (quality, performance, time, accuracy) for both square and slipping knots in students and residents. 5
- Experience matters: Experienced surgeons complete intracorporeal knot tying in 97.3 seconds vs 265.3 seconds for residents. 9
- Mechanical assist benefit: Greatest time savings for least experienced surgeons (51% reduction vs 30% for experts). 9
Robotic Surgery Training Requirements
- Preclinical dry lab practice: Repetition of ring-peg transfer, precision cutting, simple suturing and knot tying required before clinical cases. 4
- Virtual reality simulators: Improve subsequent clinical performance and shorten learning curve, though robotic VR simulators lack full validation. 4
- Progression pathway: Master basic skills before attempting complex procedures; gain proficiency with simple concurrent procedures before complex operations. 4
Postoperative Monitoring
Wound Assessment
- Infection surveillance: Monitor for increasing pain, redness, swelling, or discharge regardless of closure method. 1, 2
- Dehiscence monitoring: Critical in first 7-10 days, particularly with interrupted sutures or adhesives. 1, 2
- Suture removal timing: Remove staples or non-absorbable sutures within 7-10 days. 2
Management of Complications
- Non-adhering sutures: Replace with continuous subcuticular technique for lower dehiscence rates. 3
- Hypotony after sclerotomy: Short period of pressure patching acceptable if no serious signs; persistent hypotony requires wound revision. 4
- Conjunctival erosion: Use topical antibiotics until surgical revision with adequate release, debridement, and re-covering with pericardium. 4