The Undisputed King of Suture Strength: Stainless Steel
While not the most common due to its rigidity and handling difficulty, stainless steel wire is unequivocally the strongest suture material available. Made from a low-carbon 316L stainless steel alloy, it is non-absorbable and provides exceptional, long-lasting wound security without losing tensile strength over time. Its use is typically reserved for highly specific, high-tension scenarios, such as certain orthopedic procedures for internal fixation and sternal closure following cardiac surgery. Its inert nature means it elicits minimal tissue reaction, and it is highly resistant to infection.
Other High-Strength Non-Absorbable Options
For most applications requiring long-term strength, surgeons turn to other non-absorbable synthetic materials that are easier to handle than steel wire. These include:
- Polypropylene (Prolene®): A monofilament suture known for its smooth passage through tissue and high tensile strength. It is biologically inert and retains its strength indefinitely, making it a preferred choice for cardiovascular and vascular surgery. Its main disadvantage is its high memory, which can make handling challenging.
- Polyester (Ethibond®): A braided, non-absorbable suture that is exceptionally strong, soft, and easy to handle. While its braided nature can theoretically harbor bacteria more easily than a monofilament, it offers excellent knot security and is used in a wide range of procedures, including orthopedic and cardiac surgeries.
- UHMWPE (Ultra-High Molecular Weight Polyethylene): Modern, high-strength braided sutures used especially in orthopedic and sports medicine for tendon and ligament repair. Materials like Arthrex FiberLoop are examples of this durable category, known for their high tensile strength.
The Strongest Absorbable Sutures
For wounds that need temporary support, absorbable sutures are used. While they will eventually lose strength and be broken down by the body, some offer superior initial tensile strength compared to others.
- Polydioxanone (PDS): As a monofilament absorbable suture, PDS offers a high initial tensile strength and provides much longer wound support than many other absorbable options, retaining some strength for several weeks. It is particularly useful for slower-healing tissues where prolonged support is needed, such as abdominal wall closure.
- Polyglactin 910 (Vicryl®): This braided absorbable suture has moderate tensile strength and excellent handling characteristics. While its strength diminishes faster than PDS, recent studies have shown improved tensile strength compared to older data, making it a reliable option for many soft tissue closures.
- Poliglecaprone 25 (Monocryl®): A very smooth, monofilament absorbable suture with excellent initial tensile strength. It reabsorbs quickly and causes minimal tissue reaction, making it suitable for skin closures where a good cosmetic outcome is desired.
Monofilament vs. Braided: A Strength and Risk Trade-Off
The structure of a suture material plays a significant role in its overall performance, affecting not only strength but also handling and infection risk.
- Monofilament Sutures: These are single-strand threads that pass smoothly through tissue with minimal drag, reducing trauma. They are less prone to harboring bacteria, making them ideal for contaminated or infected areas. However, their high memory and poor knot security can make them more challenging to handle. Examples include stainless steel, PDS, and polypropylene.
- Braided (Multifilament) Sutures: Composed of several twisted or braided strands, these offer greater tensile strength and superior handling due to their flexibility and excellent knot security. The main drawback is their potential to act as a nidus for infection through a process known as capillarity, where bacteria can travel along the thread. Examples include polyester and Vicryl.
Factors Influencing Suture Strength in Practice
While the intrinsic properties of the material are important, a suture's in-use strength is also affected by other variables:
- Suture Gauge: The size of the suture, measured by its diameter. The rule of thumb is that the strength of a suture is proportional to the square of its diameter, meaning larger gauges are inherently stronger. However, surgeons select the smallest possible gauge to minimize tissue trauma.
- Knot Security: A knot can be the weakest point in a suture line. The number and type of throws used to tie a knot significantly impact its strength and security. Surgeon's knots are often used to increase knot stability.
- Tissue Environment: Factors such as infection, inflammation, or exposure to harsh fluids (e.g., urine, bile) can degrade certain suture materials over time, reducing their effective strength.
- Handling and Technique: Improper technique or excessive force when tying can weaken the suture or damage the needle connection point.
Suture Material Comparison Table
| Suture Material | Type | Absorbable? | Key Strengths | Considerations | Typical Uses |
|---|---|---|---|---|---|
| Stainless Steel Wire | Monofilament/Braided | No | Highest tensile strength, inert, infection resistant | Hard to handle, stiff, requires specific tools | Orthopedics, sternal closure |
| Polypropylene (Prolene) | Monofilament | No | High tensile strength, smooth passage, inert | High memory, requires secure knots | Vascular, cardiovascular surgery |
| Polyester (Ethibond) | Braided | No | High tensile strength, excellent handling, knot security | Can increase infection risk, slight tissue drag | Orthopedics, cardiac surgery |
| UHMWPE (FiberLoop) | Braided | No | High tensile strength, strong abrasion resistance | High cost | Orthopedic soft tissue repair |
| Polydioxanone (PDS) | Monofilament | Yes (Slow) | High initial strength, long absorption time | Can be stiff | Abdominal wall, fascia closure |
| Polyglactin 910 (Vicryl) | Braided | Yes (Medium) | Moderate strength, great handling, excellent knots | Faster absorption than PDS, moderate strength | Soft tissue, oral surgery |
| Poliglecaprone (Monocryl) | Monofilament | Yes (Rapid) | High initial strength, very smooth, minimal reactivity | Rapid absorption | Skin closure |
Conclusion: More Than Just Tensile Strength
Determining which type of suture is the strongest is more nuanced than simply picking the material with the highest tensile strength. While stainless steel wire holds that title, its clinical use is limited. In practice, surgeons evaluate the required duration of wound support, tissue type, and potential for infection before selecting a material. The strongest suture for a specific procedure may not be the one with the highest absolute strength but rather the one that provides the optimal balance of strength, handling, and biocompatibility for a successful patient outcome. Understanding the various properties of different absorbable and non-absorbable options is essential for making an informed decision in wound closure. For further information on the mechanical properties of sutures, consult reliable sources like the National Institutes of Health.
