Total Knee Replacement: Suture Types, Properties, and Selection

What Sutures Are Used in Total Knee Replacement?

Total knee replacement (TKR) surgery primarily employs a sophisticated combination of absorbable and non-absorbable sutures, along with other closure methods, meticulously selected by the orthopedic surgeon based on the specific anatomical layer being closed to ensure optimal healing, structural integrity, and long-term functional recovery.

Understanding the Surgical Closure Process in TKR

Following the successful implantation of prosthetic components in a Total Knee Replacement, the meticulous closure of the surgical incision is a critical phase. This process involves re-approximating multiple distinct tissue layers, each with unique biomechanical properties and healing characteristics. Proper closure is paramount for minimizing the risk of infection, promoting efficient wound healing, reducing scar tissue formation, and restoring the structural integrity necessary for early rehabilitation and long-term joint function. The layers typically closed include:

• Deep Joint Capsule and Synovium: The innermost layer, directly surrounding the new joint.
• Muscle and Tendon Fascia: The strong connective tissue sheaths covering muscles (e.g., quadriceps) and tendons that were incised to access the joint.
• Subcutaneous Tissue: The layer of fat and loose connective tissue beneath the skin.
• Skin: The outermost protective barrier.

Key Properties of Surgical Sutures

The choice of suture material is not arbitrary; it's a strategic decision based on the specific demands of the tissue being repaired. Key properties considered by surgeons include:

• Absorbable vs. Non-Absorbable:
  • Absorbable sutures are designed to lose their tensile strength and eventually dissolve within the body over a predictable timeframe, typically through hydrolysis or enzymatic degradation. They are ideal for tissues that heal relatively quickly and no longer require suture support once healed.
  • Non-absorbable sutures retain their tensile strength indefinitely and remain permanently in the body (or are removed post-operatively). They are used when long-term tissue approximation or permanent structural support is required.
• Monofilament vs. Multifilament:
  • Monofilament sutures consist of a single strand, offering smoother passage through tissue and less propensity for bacterial wicking (capillarity), thus potentially lower infection risk. However, they can be more prone to kinking and require more knots for security.
  • Multifilament sutures (braided or twisted) consist of multiple strands. They are generally stronger, more flexible, and offer better knot security. Their braided nature, however, can increase tissue drag and potentially harbor bacteria.
• Tensile Strength: The amount of force the suture can withstand before breaking. This is crucial for matching the suture's strength to the tension and healing properties of the tissue.
• Knot Security: The ability of the suture to hold a knot securely without slippage, which is vital for maintaining tissue approximation.
• Tissue Reactivity: The degree of inflammatory response the suture material elicits in the body. Lower reactivity is generally preferred to minimize inflammation and promote healing.

Common Suture Types Used in Total Knee Replacement

The specific sutures used can vary based on surgeon preference, patient factors, and the individual surgical approach, but certain types are commonly employed for different layers:

• For Deep Tissue Layers (Joint Capsule, Tendon/Muscle Fascia):

  • These layers require strong, reliable closure to provide immediate stability to the joint and facilitate early mobilization.
  • Polydioxanone (PDS II): A popular absorbable, monofilament suture known for its prolonged strength retention (up to 6-8 weeks) and minimal tissue reactivity. It's often chosen for capsular or fascial closure where extended support is beneficial during the initial healing phase.
  • Polyglactin 910 (Vicryl): A braided, absorbable suture that retains strength for about 2-3 weeks. While widely used in many surgical procedures, its use in primary weight-bearing fascial closure for TKR might be limited due to its shorter strength retention compared to PDS, but it can be used for less critical deep layers or subcutaneous closure.
  • Polyester (Ethibond, Mersilene): These are non-absorbable, braided sutures. While less common for routine deep closure in TKR due to the desire to use absorbable materials, they might be considered in specific cases where permanent, high-tensile strength support is deemed necessary, though their multifilament nature can increase tissue drag and potential for infection.
  • Polypropylene (Prolene): A non-absorbable, monofilament suture. Offers excellent strength and minimal tissue reaction. Less commonly used for deep closure in TKR but may be considered for specific situations requiring permanent, smooth, low-friction support.

• For Subcutaneous Layer:

  • The goal here is to approximate the subcutaneous fat, reduce dead space (which can collect fluid and lead to hematoma or seroma), and relieve tension on the skin closure.
  • Polyglactin 910 (Vicryl): Often used for its excellent handling properties and predictable absorption profile.
  • Poliglecaprone 25 (Monocryl): A monofilament, absorbable suture with good handling and rapid absorption, often favored for subcutaneous closure due to its low tissue reactivity and smooth passage.

• For Skin Closure:

  • The outermost layer requires closure that promotes good cosmetic outcomes, prevents infection, and allows for easy removal if non-absorbable.
  • Non-absorbable sutures (e.g., Nylon, Polypropylene/Prolene): Commonly used for interrupted or continuous running sutures. These are typically removed 10-14 days post-operatively. They offer strong, reliable closure and are easily visible for removal.
  • Absorbable sutures (e.g., Fast-absorbing Gut, Monocryl): Sometimes used for subcuticular closure, where the suture is placed just beneath the skin surface and does not require removal. This method can offer a good cosmetic result.
  • Surgical Staples: While not sutures, staples are a very common and efficient method for skin closure in TKR. Made of stainless steel or titanium, they provide strong, rapid closure and are removed post-operatively, similar to non-absorbable sutures.
  • Tissue Adhesives (e.g., Dermabond): Often used in conjunction with subcuticular sutures or staples to provide an additional layer of skin protection, reduce the need for dressings, and improve cosmetic outcomes.

The Rationale Behind Suture Selection

The surgeon's decision-making process for suture selection is highly nuanced and evidence-based. It considers:

• Tissue Type and Healing Time: Tissues with slower healing rates or those under significant tension (e.g., fascia) require sutures with longer strength retention.
• Desired Strength and Duration of Support: The suture must provide adequate tensile strength until the tissue has healed sufficiently to bear its own loads.
• Risk of Infection: Monofilament sutures are generally preferred in areas prone to infection due to their lower capillarity.
• Patient Factors: Individual healing capacity, co-morbidities (e.g., diabetes), and medication use can influence suture choice.
• Surgeon Preference and Experience: Ultimately, the surgeon's familiarity and comfort with specific materials play a role, often guided by outcomes data and ongoing research.

Post-Operative Considerations and Healing

After total knee replacement, diligent wound care is essential. The sutures or staples used for skin closure will need to be monitored. Non-absorbable skin sutures or staples are typically removed by a healthcare professional within 10-14 days, depending on the surgeon's protocol and the healing progress. Absorbable subcuticular sutures dissolve internally and do not require removal. Proper wound hygiene, monitoring for signs of infection (redness, swelling, discharge, fever), and adherence to post-operative instructions are crucial for optimal healing and the success of the knee replacement.

Conclusion

The selection of sutures in total knee replacement is a sophisticated aspect of orthopedic surgery, underscoring the importance of precise anatomical knowledge and material science. By strategically employing a range of absorbable and non-absorbable materials, each chosen for its specific properties and suitability for different tissue layers, orthopedic surgeons optimize the healing environment, ensure the structural integrity of the newly implanted joint, and lay the groundwork for effective rehabilitation and a successful long-term outcome for the patient.