Surgical suture thread is a critical medical device designed to approximate (hold together) tissues during wound healing, whether after trauma, surgical incisions, or reconstructive procedures. Its selection directly impacts wound closure strength, infection risk, scar formation, and patient recovery time. Unlike generic "threads," surgical sutures are engineered to meet strict regulatory standards (e.g., ISO 10405, FDA 21 CFR Part 820) for biocompatibility, tensile strength, and degradation profiles. This article provides a comprehensive overview of surgical suture threads, including classification by material, key properties, clinical applications, selection criteria, innovations, and post-closure care—essential for healthcare professionals (surgeons, nurses, physician assistants) and anyone seeking to understand this foundational surgical tool.
Surgical sutures are defined by two primary characteristics: absorbability (whether the body breaks them down over time) and material composition (natural or synthetic). This classification dictates their use in specific tissues and procedures.
1.1 Classification by Absorbability
The most fundamental distinction is between absorbable and non-absorbable sutures, as this determines whether removal is required and how long the suture provides tissue support.
A. Absorbable Sutures
Absorbable sutures are designed to be enzymatically or hydrolytically degraded by the body, eliminating the need for removal—critical for internal tissues where suture retrieval would be invasive (e.g., gastrointestinal mucosa, uterine fascia). Their "absorption profile" (time to full degradation) and "tensile strength retention" (how long they maintain support) guide clinical use.
| Suture Material | Source/Composition | Tensile Strength Retention | Full Absorption Time | Key Clinical Applications |
|------------------------|---------------------------------------------|-----------------------------------|----------------------|-------------------------------------------------------------------------------------------|
| Catgut (Plain/Chromic) | Natural (sheep/cow intestinal submucosa) | Plain: 7–10 days; Chromic: 14–21 days | Plain: 70–90 days; Chromic: 90–120 days | Plain: Superficial soft tissue (e.g., oral mucosa, minor skin lacerations). <br> Chromic: Moist tissues (e.g., vaginal, gastrointestinal, or ophthalmic conjunctiva) (chromium coating slows absorption). |
| Polyglycolic Acid (PGA) | Synthetic (linear aliphatic polyester) | 2–3 weeks | 60–90 days | General surgery (e.g., abdominal wall fascia, bowel anastomosis), pediatric procedures (no removal needed). |
| Polylactic Acid (PLA) & Copolymers (e.g., Vicryl®) | Synthetic (PLA or PLA-co-glycolide) | Vicryl®: 3–4 weeks; Vicryl® Plus (antibacterial): 3–4 weeks | Vicryl®: 70–100 days | Soft tissue approximation (e.g., muscle, subcutaneous fat), gynecologic surgery (e.g., hysterectomy), orthopedic soft tissue repair (e.g., tendon sheaths). |
| Polydioxanone (PDS II®) | Synthetic (polyether-ester) | 6–8 weeks | 180–240 days | High-tension tissues requiring prolonged support (e.g., abdominal wall closure in obese patients, pediatric cardiac tissue, hernia repair). |
| Polyglyconate (Maxon®) | Synthetic (glycolide-co-trimethylene carbonate) | 4–6 weeks | 120–150 days | Urological surgery (e.g., bladder neck repair), colorectal anastomosis (resists degradation in fecal environment). |
B. Non-Absorbable Sutures
Non-absorbable sutures are not degraded by the body and remain indefinitely unless surgically removed. They are used for tissues requiring long-term or permanent support, or for external closure where removal is straightforward.
| Suture Material | Source/Composition | Key Properties | Key Clinical Applications |
|------------------------|---------------------------------------------|-----------------------------------------|-------------------------------------------------------------------------------------------|
| Silk | Natural (silkworm fibroin) | High pliability; excellent knot security; poor moisture resistance (prone to bacterial colonization). | Cardiovascular surgery (historical use in vessel anastomosis), ophthalmic surgery (e.g., corneal sutures), cosmetic surgery (fine scarring). |
| Nylon (Polyamide) | Synthetic (polyamide polymer) | High tensile strength; low tissue reactivity; available as monofilament or braided. | Skin closure (e.g., post-surgical incisions), orthopedic surgery (e.g., tendon repair), vascular surgery (non-absorbable vessel ligatures). |
| Polypropylene (Prolene®) | Synthetic (polyolefin) | Monofilament; ultra-low tissue reactivity; resistant to chemicals and infection. | Cardiothoracic surgery (e.g., coronary artery bypass grafts), neurosurgery (e.g., dura mater repair), plastic surgery (e.g., facial reconstruction). |
| Polyester (Ethibond®) | Synthetic (polyethylene terephthalate) | Braided; high strength; often coated with Teflon® for reduced friction. | Orthopedic surgery (e.g., joint capsule repair), cardiovascular surgery (e.g., valve replacement sutures), hernia mesh fixation. |
| Stainless Steel | Synthetic (alloy of steel, chromium, nickel) | Highest tensile strength; non-reactive; available as monofilament or twisted. | Orthopedic trauma (e.g., bone fracture fixation), sternotomy closure (post-cardiac surgery), large skin wounds (e.g., burns). |
1.2 Secondary Classification: Monofilament vs. Braided
Sutures are further categorized by their physical structure, which impacts handling, knot security, and tissue reactivity:
| Structure Type | Design | Advantages | Disadvantages | Ideal Uses |
|----------------|---------------------------------------------|-----------------------------------------------------------------------------|-------------------------------------------------------------------------------|-----------------------------------------------------------------------------|
| Monofilament | Single, continuous strand | Low tissue drag (easy to pass through tissues); low infection risk (no interstices for bacteria); minimal tissue irritation. | Poor knot security (requires more throws to secure knots); stiffer handling. | Delicate tissues (e.g., blood vessels, nerves), contaminated wounds (reduced infection risk). |
| Braided | Multiple strands twisted/woven together | Excellent knot security (fewer throws needed); flexible handling (easy to manipulate in tight spaces). | High tissue drag (may damage delicate tissues); higher infection risk (bacteria can lodge in braid interstices); may cause tissue irritation. | High-tension tissues (e.g., fascia, tendons), non-contaminated wounds. |
2. Key Properties of Surgical Suture Threads
Surgeons evaluate five critical properties when selecting suture thread—these directly influence clinical outcomes:
2.1 Tensile Strength
The maximum force a suture can withstand before breaking. Measured in pounds (lbs) or newtons (N), it must match the tissue’s required support (e.g., 2–0 suture for skin vs. 0 or 1 suture for abdominal fascia).
2.2 Knot Security
The ability of the suture to hold a knot without slipping or untying. Braided sutures (e.g., silk, Vicryl®) have better knot security than monofilaments (e.g., polypropylene), which require 4–5 throws per knot vs. 2–3 for braids.
2.3 Tissue Reactivity
The degree to which the suture elicits an inflammatory response. Synthetic monofilaments (e.g., polypropylene) have the lowest reactivity; natural sutures (e.g., catgut) or braided synthetics (e.g., polyester) may cause mild inflammation (normal during absorption).
2.4 Handling Characteristics
How easily the suture is passed through tissue, manipulated, and tied. Silk and braided Vicryl® are "easy-handling" (flexible, conformable); stainless steel and monofilament nylon are stiffer (require more skill to handle).
2.5 Biocompatibility
The suture’s ability to coexist with living tissue without causing toxicity, allergic reactions, or foreign body responses. All surgical sutures must meet ISO 10993 standards for biocompatibility—e.g., chromium-coated catgut is contraindicated in patients with nickel allergies.
3. Clinical Selection Criteria: How to Choose the Right Suture Thread
Suture selection is a personalized process based on four core factors—no single "best" suture exists for all scenarios:
3.1 Tissue Type & Location
- Delicate tissues (eyes, blood vessels, nerves): Monofilament sutures (e.g., polypropylene, 6–0 to 10–0 size) to minimize tissue damage.
- High-tension tissues (fascia, tendons, bone): Non-absorbable or long-absorbable sutures (e.g., PDS II®, polyester, stainless steel) with high tensile strength.
- Moist tissues (gastrointestinal, vaginal): Chromic catgut or synthetic absorbables (e.g., Vicryl®) that resist premature degradation in moisture.
- Skin: Non-absorbable monofilaments (e.g., nylon, polypropylene) for easy removal and minimal scarring; absorbables (e.g., fast-absorbing Vicryl®) for pediatric or hard-to-reach areas (e.g., scalp).
3.2 Patient Factors
- Age: Pediatric patients (use absorbables to avoid suture removal anxiety); elderly patients (use low-reactivity sutures, as skin is thin and prone to irritation).
- Healing Capacity: Patients with diabetes, immunocompromise, or malnutrition (use non-absorbables or long-absorbables to provide prolonged support, as healing is delayed).
- Allergies: Avoid natural sutures (catgut, silk) in patients with animal allergies; avoid nickel-containing sutures (stainless steel) in nickel-sensitive patients.
3.3 Surgical Procedure & Wound Status
- Clean wounds (elective surgery): Braided sutures (e.g., silk, Vicryl®) for better knot security.
- Contaminated/infected wounds: Monofilament sutures (e.g., polypropylene) to reduce bacterial colonization; avoid absorbables (degradation may worsen inflammation).
- Laparoscopic/robotic surgery: Barbed sutures (see Section 4) or monofilaments (easy to pass through trocars).
3.4 Surgeon Preference & Technique
Surgeons often select sutures based on familiarity with handling—e.g., a cardiovascular surgeon may prefer polypropylene for vessel anastomosis, while a plastic surgeon may favor silk for cosmetic closure.
4. Innovations in Surgical Suture Threads
Advancements in materials science have led to next-generation sutures that address unmet clinical needs:
4.1 Antibacterial-Coated Sutures
Sutures coated with triclosan (e.g., Vicryl® Plus, Monocryl® Plus) or chlorhexidine (e.g., Ethilon® Plus) reduce bacterial colonization by 50–70% (per clinical trials), lowering the risk of surgical site infections (SSIs)—critical for high-risk procedures (e.g., colorectal surgery, orthopedic joint replacement).
4.2 Barbed Sutures
Monofilament sutures with tiny, bidirectional barbs (e.g., V-Loc™, Quill™) eliminate the need for knots. The barbs anchor into tissue, providing secure approximation while reducing operating time (20–30% faster than traditional sutures) and knot-related complications (e.g., knot granulomas). Ideal for laparoscopic surgery (e.g., hysterectomy, hernia repair) and cosmetic procedures (e.g., facelifts).
4.3 Biodegradable Composite Sutures
Sutures combining two absorbable materials (e.g., PGA-PLA copolymers) to tailor tensile strength retention—e.g., a suture that maintains 50% strength for 4 weeks (supports fascia healing) and fully absorbs by 12 weeks (avoids long-term foreign body reaction).
4.4 Radiopaque Sutures
Sutures impregnated with barium sulfate or tungsten (e.g., PDS II® Radiopaque) are visible on X-rays/CT scans. Used in procedures where suture location must be verified (e.g., orthopedic fracture fixation, vascular anastomosis).
5. Post-Closure Care: Ensuring Suture Integrity & Wound Healing
Proper care of sutured wounds preserves suture function and prevents complications:
5.1 Wound Cleaning
- Clean wounds: Gently clean with mild soap and water daily; pat dry (avoid rubbing).
- Contaminated wounds: Follow surgeon instructions (may require antiseptic washes, e.g., chlorhexidine).
- Avoid: Hydrogen peroxide or alcohol (irritates tissue and may weaken suture integrity).
5.2 Infection Monitoring
Watch for signs of SSI:
- Redness, warmth, or swelling extending beyond the wound edge.
- Purulent (yellow/green) discharge or foul odor.
- Fever (>38°C/100.4°F) or severe pain at the site.
Report any signs to a healthcare provider immediately—untreated infections can break down sutures and delay healing.
5.3 Suture Removal (for Non-Absorbables)
- Timing: Depends on tissue location (e.g., face: 5–7 days; scalp: 7–10 days; trunk/extremities: 10–14 days; joints: 14–21 days).
- Technique: Performed by a trained professional using sterile scissors and forceps—cutting the suture close to the skin and pulling gently to avoid tissue trauma.
5.4 Activity Restrictions
Avoid tension on the sutured area (e.g., lifting heavy objects after abdominal surgery, bending after knee surgery) to prevent suture breakage or wound dehiscence (opening).
