Introduction
A trauma surgeon stands over a high-tension laceration on a patient's knee, weighing options: absorbable sutures that might fail before healing completes, or non-absorbable materials requiring a follow-up removal visit.
For wounds bearing significant mechanical stress—joints, fascia, tendons—the choice often favors non-absorbable sutures, materials engineered to retain strength long after absorbable alternatives dissolve. While modern bioabsorbable closure systems continue advancing, non-absorbable materials remain prevalent in high-stress wound environments.
Surgeons balance closure speed, cosmetic outcomes, and patient convenience when selecting materials. Non-absorbable sutures address specific clinical challenges but introduce removal logistics and complications like stitch abscesses or railroad scarring if retained too long.
Understanding the trade-offs helps optimize wound closure decisions. This article covers:
- Material types and their performance profiles
- Clinical applications across surgical specialties
- Evidence-based removal timelines and techniques
- Complications of improper use or retention
TLDR
- Non-absorbable sutures maintain strength beyond 60 days and require removal
- Common materials include silk, nylon, polypropylene, and stainless steel
- Monofilament sutures reduce infection risk; multifilament offers better handling
- Removal timing depends on location: facial sutures in 3-5 days, joint sutures in 14+ days
- Bioabsorbable closure systems eliminate removal appointments and close 7X faster than traditional sutures
What Are Non-Absorbable Sutures?
Non-absorbable surgical sutures are flexible strands engineered to resist breakdown by body enzymes and maintain tensile strength for more than 60 days in living tissue, according to FDA and USP standards. Unlike absorbable sutures that lose the majority of their strength within two months, non-absorbable materials provide long-term or permanent support.
Key Characteristics
Enzymatic Resistance: These materials resist breakdown by body enzymes and tissue fluids during critical healing phases.
While some materials like silk eventually degrade over years, they maintain functional strength far longer than absorbable alternatives.
Long-Term Tensile Strength: Non-absorbable sutures sustain mechanical loads throughout the healing process and beyond. Stainless steel and synthetic polymers like polypropylene maintain near-original strength indefinitely.
Minimal Degradation: Most synthetic non-absorbable sutures show negligible strength loss over months to years, though nylon loses approximately 15-20% tensile strength annually via hydrolysis.
When Non-Absorbable Sutures Are Preferred
These characteristics make non-absorbable sutures the preferred choice in specific clinical scenarios:
- High-Tension Areas: Joints, extremities, and abdominal fascia experience constant mechanical stress that can cause absorbable sutures to fail before tissues regain sufficient strength
- Slow-Healing Tissues: Tendons, ligaments, and fascia heal gradually—abdominal fascia regains only 8% of original strength at 1-2 weeks—requiring prolonged support
- Permanent Support Needs: Vascular anastomosis, heart valve attachment, and orthopedic fixation demand materials that never lose strength
Types of Non-Absorbable Suture Materials
Natural Non-Absorbable Sutures
Silk Sutures
Composition: Derived from silkworm cocoon protein filaments, typically braided and coated with wax or silicone to reduce tissue drag.
The "Non-Absorbable" Exception: Despite classification as non-absorbable, silk loses approximately 30% tensile strength by 14 days and 50% by one year. Complete absorption via phagocytosis may occur after two years.
Clinical Applications:
- Dental surgery and oral mucosal repairs
- Internal ligations where permanent strength isn't critical
- Situations prioritizing handling over longevity
Advantages:
- Exceptional handling and pliability
- Superior knot security due to braided structure
- Minimal allergic reactions
Disadvantages:
- Lowest tensile strength among non-absorbables
- Significant inflammatory tissue reaction
- Contraindicated in contaminated wounds (capillary wicking harbors bacteria)
- Eventual degradation makes it unsuitable for permanent support
While natural materials like silk offer superior handling, they sacrifice strength and longevity. Synthetic materials address these limitations through engineered polymers designed for specific clinical needs.
Synthetic Non-Absorbable Sutures
Polypropylene (Prolene/Surgipro)
Material Properties: Isotactic crystalline stereoisomer of polypropylene in monofilament form.
Tissue Reaction: Extremely inert with minimal acute inflammatory response. Least thrombogenic of all monofilament sutures.
Clinical Profile:
- Preferred for: Vascular anastomosis, cardiovascular surgery, running subcuticular skin closure
- Advantage: Low thrombogenic potential prevents clot formation in blood vessel repairs
- Limitation: High plasticity means it stretches with edema but may remain loose after swelling resolves
Polyamide/Nylon (Ethilon/Nurolon)
Composition: Long-chain aliphatic polymers (Nylon 6 or Nylon 6,6) derived from caprolactam.
Degradation Rate: Loses 15-20% tensile strength per year through hydrolysis, though remains functional for years.
Nylon's elasticity makes it particularly versatile for applications requiring flexibility.
Key Applications:
- General soft tissue surgery
- Skin closure where elasticity accommodates swelling
- Situations requiring balance of strength and flexibility
Handling Characteristics:
- High memory (tendency to return to package shape)
- Requires 3-5 knot throws for security vs. 2-3 for silk
- Excellent elasticity maintains tension through healing
Polyester (Mersilene/Ethibond)
Composition: Poly(ethylene terephthalate) fibers, typically braided.
Polyester delivers exceptional strength for high-load applications.
Performance Profile:
- Very strong with indefinite tensile retention
- Often coated with polybutilate to reduce significant tissue drag
- Moderate tissue reaction
Applications:
- Orthopedic procedures (tendon/ligament repair)
- Cardiac valve replacement
- Joint stabilization requiring maximal strength
Challenges:
- Poor knot security without coating
- Contraindicated in infected wounds (braided structure harbors bacteria)
- High tissue drag can cause trauma during passage
Polybutester (Novafil)
Unique Properties: Copolymer combining butylene terephthalate and polytetramethylene ether glycol for exceptional elasticity.
Clinical Advantage: Elongates under load (accommodating edema) then returns to original length, reducing railroad track scarring in swelling-prone tissues. This "memory" behavior distinguishes it from polypropylene, which permanently stretches.
Primary Applications: Skin closure in edematous tissues where tension fluctuates during healing.
Handling: Moderate memory with good knot security, though less pliable than nylon.
Metallic Non-Absorbable Sutures
Stainless Steel
Composition: 316L (low carbon) stainless steel alloy conforming to ASTM F138 Grade 2 standards.
Performance Characteristics:
- Highest tensile strength of all suture materials (up to ~1500 N in sternal closure)
- Completely inert and non-corrosive
- Minimal inflammatory reaction
Handling Challenges:
- Prone to kinking (can render wire useless)
- Sharp ends may traumatize tissue or puncture gloves
- Requires specialized technique
Modern Applications:
- Sternal closure after cardiac surgery
- Orthopedic cerclage and bone fixation
- Abdominal wall closure in high-risk patients
- Infected wounds (monofilament doesn't harbor bacteria)
Monofilament vs Multifilament Non-Absorbable Sutures
Monofilament Construction
Structure: Single continuous strand (examples: polypropylene, nylon, stainless steel).
Key advantages:
- Smooth passage through tissue with minimal trauma
- Lower infection risk—no spaces for bacterial colonization
- Reduced tissue drag, preferred for contaminated wounds
Trade-offs:
- Poor knot security due to high memory
- Requires additional throws to prevent unraveling
- Stiffer handling compared to braided alternatives
Multifilament Construction
Structure: Multiple filaments braided or twisted together (examples: silk, polyester).
Key advantages:
- Superior handling and pliability make tying easier
- Excellent knot security via friction between fibers
Trade-offs:
- Capillary action wicks bacteria into wound along fiber grooves
- Higher infection risk in contaminated fields
- Increased tissue drag (sawing effect)
Understanding these trade-offs helps you select the right suture for each clinical scenario.
Selection Guidance
Choose Monofilament When:
- Working in contaminated or infected fields
- Minimizing tissue trauma is critical
- Working with vascular tissue (thrombosis risk)
Choose Multifilament When:
- Knot security is paramount (internal ligations)
- Operating in clean, uncontaminated fields
- Handling ease improves surgical efficiency
Clinical Applications and Use Cases by Specialty
Cardiovascular Surgery
Material of Choice: Polypropylene (Prolene)
Rationale: Least thrombogenic synthetic monofilament with permanent strength retention. Critical for vascular anastomosis where clot formation could be catastrophic.
Specific applications include:
- Arterial and venous anastomosis
- Vascular graft attachment
- Heart valve replacement fixation
Orthopedic Surgery
Non-elastic materials are essential because they prevent elongation under cyclical loading while providing permanent support for slow-healing connective tissues.
Preferred materials include:
- Polyester (Ethibond) — Tendon and ligament repairs (rotator cuff, cruciate ligament) requiring high tensile strength and superior knot security
- Stainless Steel — Bone fixation via cerclage and tendon repairs bearing maximal loads
Skin Closure
Material selection varies based on the specific closure requirements:
| Material | Best For | Advantages | Considerations |
|---|---|---|---|
| Nylon | General skin closure | High elasticity accommodates swelling | Loses 15-20% strength/year |
| Polypropylene | Running subcuticular | Low tissue drag (easy removal), inert | May loosen after edema resolves |
| Silk | Mucosal tissues | Excellent handling | Higher inflammatory response |
Cosmetic Considerations: Systematic reviews show no significant cosmetic difference between nylon and polypropylene, though nylon may cause slightly more removal discomfort.
Fascia and Tendon Repair
High-tension, slow-healing tissues demand permanent or near-permanent support. Fascia regains only 8% strength at 1-2 weeks post-surgery, making absorbable sutures inadequate for these applications.
Recommended materials:
- Polypropylene — Fascial closure with inert, permanent strength
- Polyester — Tendon repairs requiring maximal tensile strength
- Stainless steel — High-risk abdominal closures needing maximum security
Special Considerations
Contaminated Wounds: Strictly use monofilament sutures. Multifilament materials harbor bacteria in fiber grooves, increasing infection and sinus formation risk.
Plastic/Reconstructive Surgery: Prioritize materials minimizing inflammatory response (polypropylene, nylon) and plan early removal to prevent railroad scarring.
Critical Contraindications: Never use silk in contaminated wounds, vascular repairs, or where permanent strength is required.
Removal Best Practices and Timeline
Standard Removal Timelines
Timing balances tensile support needs against scarring and infection risks:
| Location | Removal Timeline | Rationale |
|---|---|---|
| Face/Eyelids | 3-5 days | Minimize cosmetic scarring |
| Scalp | 7-10 days | Balance healing with hair coverage |
| Neck | 7 days | Moderate tension, visible area |
| Trunk (Chest/Back) | 10-14 days | Higher tension requires longer support |
| Upper Extremities | 7-10 days | Moderate movement and tension |
| Lower Extremities | 10-14 days | High tension, slower healing |
| Joints/High Tension | 14+ days | Prevent dehiscence under stress |
| Palms/Soles | 14-21 days | Thick skin, high mechanical stress |
Removal Technique
Pre-Removal Assessment:
- Check for infection signs (redness, warmth, drainage, odor)
- Verify wound edges are approximated
- Confirm adequate healing progress
Step-by-Step Process:
- Cleanse wound with antiseptic solution
- Lift knot with sterile forceps
- Cut below the knot close to skin surface (prevents dragging contaminated external suture through tissue)
- Pull gently in direction of wound to minimize trauma
- Inspect wound after each suture removal for dehiscence
Minimizing Discomfort:
- Apply topical anesthetic if patient is anxious
- Remove alternate sutures first to assess wound stability
- Work efficiently but gently
Signs Sutures Are Ready vs. Requiring Early Removal
Ready for Removal:
- Wound edges well-approximated
- No drainage or inflammation
- Timeline appropriate for anatomical location
- Patient reports minimal discomfort
Requires Early Removal:
- Infection present (purulent drainage, erythema, warmth)
- Tissue blanching from excessive tension
- Inflammatory or allergic tissue reaction develops
- Severe patient discomfort reported
Consequences of Not Removing Non-Absorbable Sutures
Delayed or skipped removal leads to several complications:
- Stitch abscesses develop when foreign body reaction creates localized infection, requiring incision and drainage
- Sinus tracts form as chronic drainage pathways when the body attempts to expel foreign material (may persist for months)
- Railroad track scarring occurs as prolonged retention causes cross-hatched marks where sutures cut into healing tissue
- Embedded sutures may require surgical excision and can cause chronic inflammation or permanent cosmetic defects
Modern Alternatives
Bioabsorbable systems like SubQ It! eliminate removal complications entirely. The FDA-cleared device delivers subcutaneous bioabsorbable fasteners 7X faster than manual sutures while maintaining strength for 21 days.
The fasteners absorb completely after healing, removing the need for follow-up visits. This addresses the primary drawbacks of traditional non-absorbable sutures: removal logistics, patient anxiety, and potential complications from retention or premature removal.
Frequently Asked Questions
What are non-absorbable sutures?
Non-absorbable sutures are surgical materials that retain tensile strength beyond 60 days and resist enzymatic breakdown. Most require removal when used for skin closure, though some placed internally may remain permanently.
Do non-absorbable sutures need to be removed?
Most non-absorbable sutures used for skin closure must be removed within days to weeks. However, sutures placed internally during orthopedic or cardiovascular procedures typically remain permanently as they provide ongoing structural support.
How long are non-absorbable sutures left in place?
Removal timing varies by location: 3-5 days for facial sutures, 7-10 days for scalp and arms, 10-14 days for trunk and legs, and 14+ days for joints under high tension.
When to use Prolene vs nylon?
Use Prolene (polypropylene) for cardiovascular procedures, vascular anastomosis, and situations requiring permanent inert support. Choose nylon for general soft tissue and skin closure when elasticity helps accommodate swelling during healing.
How can you tell the difference between dissolvable and non-absorbable sutures?
Always check packaging labels for material type and absorption profile first. Visually, absorbable sutures are often violet or undyed, while non-absorbables are typically blue or black. Monofilament synthetics feel stiffer than braided materials.
What is the strongest non-absorbable suture?
Stainless steel has the highest tensile strength (up to ~1500 N in some applications), followed by synthetic polyester and polypropylene. Silk is the weakest non-absorbable material, losing 50% strength by one year.
Are there alternatives to traditional sutures for wound closure?
Modern surgical wound closure includes bioabsorbable stapling systems that combine the speed of metal staplers with the cosmetic benefits of subcuticular closure. These systems, such as SubQ It!'s bioabsorbable fasteners, eliminate the need for removal while closing incisions 7X faster than manual sutures.
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