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Chemistry and Mechanics of Commonly Used Sutures and Needles
IN BRIEF
Chemistry and Mechanics of Commonly Used Sutures and Needles Daniel E. Firestone, MD, Anthony J. Lauder, MD
S
UTURE CHOICE SEEMS anecdotal. As hand surgeons,
we have been taught the principles of suture and needle selection; however, if asked to cite evidence for our preferred choice, most of us would be hard-pressed. The following brief review is a summary of the characteristics of commonly used suture and needle types, in an attempt to better understand why we follow the hidden curriculum of our mentors.
In Brief
SUTURES The ideal suture material should exhibit high tensile strength, be easy to handle, and elicit little to no tissue reaction. Bearing these requirements in mind, sutures may be categorized broadly by their permanence (absorbable or nonabsorbable) and configuration (monofilament or multifilament). These 2 categories are further divided by the multiple characteristics of each material (Table 1).1–3 Nonabsorbable sutures are either synthetic or natural, and are categorized by their respective configurations, reactivity, and memory or handling. Nonabsorbable suture is used when prolonged tension (fascial closure, tendon repair, bone anchoring, or ligament repair) is required for suitable healing to take place. These sutures cause little soft tissue reaction and will eventually become encapsulated. Nylon sutures (Ethilon, Ethicon, Inc., Somerville, NJ; Surgilon, Covidien, Mansfield, MA; and Nurolon, Ethicon, Inc.) generally lose 15% to 20% of their tensile strength per year, whereas polyester sutures (Ethibond, Ethicon, Inc.; Ticron, Covidien, Mansfield, MA; Dacron, Ethicon, Inc.; and Mersilene, FromtheDepartmentofOrthopaedicSurgeryandDivisionofPlasticandReconstructiveSurgery,University of Nebraska Medical Center, Omaha, NE. The authors acknowledge Taylor Theunissen, MD, for help during the preparation of the manuscript. Received for publication September 14, 2009; accepted in revised form October 29, 2009. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Anthony J. Lauder, MD, Department of Orthopaedic Surgery, University of Nebraska Medical Center, 981080 Nebraska Medical Center, Omaha, NE 68198-1080; e-mail: [email protected]. 0363-5023/10/35A03-0024$36.00/0 doi:10.1016/j.jhsa.2009.10.036
486 䉬 © Published by Elsevier, Inc. on behalf of the ASSH.
Ethicon, Inc.) retain their strength indefinitely. Other examples of nonabsorbable sutures include polypropylene (Prolene, Ethicon, Inc.), silk, cotton, and steel. Absorbable sutures are derived from either collagen or synthetic polymers. All absorbable sutures lose at least 50% of their strength within 4 weeks of use. For example, Vicryl (Ethicon, Inc., a braided synthetic absorbable suture material with 50% loss of strength at 2 to 3 weeks) is a reasonable choice for cutaneous wound closure, because the tensile strength of a healing incision is expected to be 50% at 4 weeks and 80% at 6 weeks. The purified serosa of bovine intestines is used for collagen-derived sutures. When treated with an aldehyde solution (which strengthens the material), the substance is called plain gut. When treated further with chromium trioxide (which strengthens and increases the resistance to absorption), the material is termed chromic gut. Collagen-based sutures are degraded by neutrophil proteolysis and are the most reactive type of absorbable sutures. Reactivity can lead to increased scarring. Synthetic polymers are degraded by hydrolysis and produce less tissue reaction. Examples of absorbable sutures include plain gut, chromic gut, polyglactin 910 (Vicryl, Ethicon, Inc.), polyglycolic acid (Dexon, Covidien), polydioxanone (PDS II, Ethicon, Inc.), poliglecaprone 25 (Monocryl, Ethicon, Inc.), polyglyconate (Maxon, Covidien), glycomer 631 (Biosyn, Covidien), and polyglytone 6211 (Caprosyn, Covidien). Suture material (both absorbable and nonabsorbable) can also be classified as monofilament or multifilament. Compared with multifilament materials, monofilament sutures have significantly less surface area. This can be a beneficial characteristic in a contaminated area where one wants to provide the least amount of surface area for bacterial colonization. Monofilament sutures have low friction and cause less tissue trauma; however, monofilaments are less pliable and have increased memory, making them somewhat more difficult to handle. The practical result of increased memory is that more throws are needed to create a secure knot. Examples of monofilament sutures include polydioxanone
487
(PDS II), poliglecaprone 25 (Monocryl), nylon (Ethilon), swage is where the suture material is attached to the and polyprolene (Prolene). Examples of multifilament suneedle. Two different processes during manufacturing tures: polyglactin 910 (Vicryl), polyglycolic acid (Dexon), are used to attach the suture material to the swage. polyester (Ethibond), and nylon (Surgilon). Channel swaging is a process in which a press creates a Numerous new suture varieties are available that can channel and the suture material is laid in the channel. be useful for specific tasks. However, one must keep in The swage is then crimped around the suture material. mind that with new technology comes new costs. For Drill swaging involves drilling a tunnel into which the flexor tendon repairs, looped suture material is placed. The Supramid (S. Jackson, Inc., EDUCATIONAL OBJECTIVES swage is then crimped ● Describe the categories of sutures based upon permanence and configu- around the suture. Alexandria, VA) suture has ration. gained popularity for use as a There are 2 main types core stitch. Another useful ● List the various uses of absorbable and non-absorbable sutures. of suture needle point: tavariety of suture that is avail- ● State the advantages and disadvantages of monofilament versus multi- pered and cutting. Tapered able as a loop is Fiberwire needles have a sharp point filament sutures. (Arthrex, Naples, FL). Fiber- ● List the difference between plain gut and chromic gut sutures. and a smooth body with no wire boasts the abilities of ● sharp edge. A tapered neeDiscuss the 3 basic parts of a suture needle. both monofilament and muldle works by spreading the Earn up to 2 hours of CME credit per JHS issue when you read the related tifilament. Its polyethylene tissue as it passes through core provides strength and articles and take the online test. To pay the $20 fee and take this month’s it. The sharpness of a tadurability against abrasion test, visit http://www.assh.org/professionals/jhs. pered needle is determined and its braided polyester by its taper ratio, typically jacket provides easier handling. Finally, Quill SRS (An8:1 or 12:1 (the higher the ratio, the sharper the giotech, Vancouver, BC.) is a variety of barbed suture tip). Typical uses of tapered needles include soft that can help strengthen wound closure. elastic tissue such as muscle or subcutaneous fat. Sutures are also classified by their size. The Suture material is less likely to cut through tissue familiar sizing nomenclature is a numeric value if a tract is made by a tapered needle. Traditionfollowed by a 0 (ie, 3-0). This is determined by the ally, tendon repair uses tapered needles; however, United States Pharmacopoeia rating system and Lam et al. found no biomechanical difference bebased on the breaking strength of the suture matetween tapered and cutting needles in tendon rerial, not the diameter. For example a 3-0 steel pair.4 suture has the same breaking strength as a 3-0 Cutting needles have a tip and 3 sharpened edges. nylon suture, but a much different diameter. Conventional cutting needles have the cutting surface on the inner curve. Unintended upward traction while NEEDLES working with a standard cutting needle may produce a shallow bite. This can create a weak point on the tract The suture needle consists of 3 basic parts. The point where the suture can cut through the tissue or skin. A begins at the tip and ends when the needle reaches its reverse cutting needle has the cutting surface on the full diameter. The body is the majority of the needle. It outer curve. Unintended downward pressure while begins where the tip ends and ends at the swage. The TABLE 1.
Suture Characteristics
Characteristic
Definition
Coefficient of friction
Suture’s relative resistance to being passed through a tissue. A higher coefficient of friction leads to increased local tissue damage. Monofilament usually has the lowest coefficient of friction.
Tensile strength
Suture’s ability to resist breakage. Strength of suture should not be significantly greater than the tissue it is approximating (if tensile strength is too high, suture will cut through tissue).
Elasticity
Suture’s ability to regain original length after deformation. Elasticity should be sufficient to accommodate tissue swelling.
Memory
Suture’s ability to return to original shape after deformation. Similar to pliability (more memory ⫽ less pliable and less knot security).
Cost
Significant issue in today’s health care arena. Newer suture materials with precision needles are generally more costly.
JHS 䉬 Vol A, March
In Brief
SUTURES AND NEEDLES
488
SUTURES AND NEEDLES
working with a reverse cutting needle may create deeper than intended tract. Both types of cutting needles are ideal for penetrating tough tissue such as skin. REFERENCES 1. Mosser SW. Sutures and needles. In: Janis JE, ed. Essentials of plastic surgery. St. Louis, MO: Quality Medical, 2007:13–19.
2. Marcus BC. Wound closure techniques. In: Baker SR, ed. Local flaps in facial reconstruction. Philadelphia: Mosby Elsevier, 2007:50 – 60. 3. Weinzweig J, Weinzweig NW. Plastic surgery techniques. In: Guyuron B, Eriksson E, Persing J, eds. Plastic surgery. Philadelphia: Saunders Elsevier, 2009:37– 44. 4. Lam WL, Garrido A, Vandermeulen J, Fagan MJ, Stanley PRW. Cutting or round-bodied needles for tendon repair. J Hand Surg 2003;28B:475– 477.
JOURNAL CME QUESTIONS Chemistry and Mechanics of Commonly Used Sutures and Needles What is the reduction in strength of monofilament and multifilament non-absorbable sutures? a. Monofilament and multifilament sutures retain their strength indefinitely. b. Monofilament sutures lose 15% to 20% of their tensile strength per year and multifilament sutures retain their strength indefinitely. c. Multifilament sutures lose 15% to 20% of their tensile strength per year and monofilament sutures retain their strength indefinitely.
d. Monofilament sutures lose 50% of their tensile strength per year and multifilament sutures retain their strength indefinitely. e. Monofilament and multifilament sutures lose 50% of their tensile strength per year. What percentage of absorbable suture strength is lost within 4 weeks of use? a. Less than 10% b. Less than 20% c. Less than 30% d. Less than 40% e. At least 50%
To take the online test and receive CME credit, go to http://www.assh.org/professionals/jhs.
In Brief JHS 䉬 Vol A, March
Chemistry and Mechanics of Commonly Used Sutures and Needles Daniel E. Firestone, MD, Anthony J. Lauder, MD
S
UTURE CHOICE SEEMS anecdotal. As hand surgeons,
we have been taught the principles of suture and needle selection; however, if asked to cite evidence for our preferred choice, most of us would be hard-pressed. The following brief review is a summary of the characteristics of commonly used suture and needle types, in an attempt to better understand why we follow the hidden curriculum of our mentors.
In Brief
SUTURES The ideal suture material should exhibit high tensile strength, be easy to handle, and elicit little to no tissue reaction. Bearing these requirements in mind, sutures may be categorized broadly by their permanence (absorbable or nonabsorbable) and configuration (monofilament or multifilament). These 2 categories are further divided by the multiple characteristics of each material (Table 1).1–3 Nonabsorbable sutures are either synthetic or natural, and are categorized by their respective configurations, reactivity, and memory or handling. Nonabsorbable suture is used when prolonged tension (fascial closure, tendon repair, bone anchoring, or ligament repair) is required for suitable healing to take place. These sutures cause little soft tissue reaction and will eventually become encapsulated. Nylon sutures (Ethilon, Ethicon, Inc., Somerville, NJ; Surgilon, Covidien, Mansfield, MA; and Nurolon, Ethicon, Inc.) generally lose 15% to 20% of their tensile strength per year, whereas polyester sutures (Ethibond, Ethicon, Inc.; Ticron, Covidien, Mansfield, MA; Dacron, Ethicon, Inc.; and Mersilene, FromtheDepartmentofOrthopaedicSurgeryandDivisionofPlasticandReconstructiveSurgery,University of Nebraska Medical Center, Omaha, NE. The authors acknowledge Taylor Theunissen, MD, for help during the preparation of the manuscript. Received for publication September 14, 2009; accepted in revised form October 29, 2009. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Anthony J. Lauder, MD, Department of Orthopaedic Surgery, University of Nebraska Medical Center, 981080 Nebraska Medical Center, Omaha, NE 68198-1080; e-mail: [email protected]. 0363-5023/10/35A03-0024$36.00/0 doi:10.1016/j.jhsa.2009.10.036
486 䉬 © Published by Elsevier, Inc. on behalf of the ASSH.
Ethicon, Inc.) retain their strength indefinitely. Other examples of nonabsorbable sutures include polypropylene (Prolene, Ethicon, Inc.), silk, cotton, and steel. Absorbable sutures are derived from either collagen or synthetic polymers. All absorbable sutures lose at least 50% of their strength within 4 weeks of use. For example, Vicryl (Ethicon, Inc., a braided synthetic absorbable suture material with 50% loss of strength at 2 to 3 weeks) is a reasonable choice for cutaneous wound closure, because the tensile strength of a healing incision is expected to be 50% at 4 weeks and 80% at 6 weeks. The purified serosa of bovine intestines is used for collagen-derived sutures. When treated with an aldehyde solution (which strengthens the material), the substance is called plain gut. When treated further with chromium trioxide (which strengthens and increases the resistance to absorption), the material is termed chromic gut. Collagen-based sutures are degraded by neutrophil proteolysis and are the most reactive type of absorbable sutures. Reactivity can lead to increased scarring. Synthetic polymers are degraded by hydrolysis and produce less tissue reaction. Examples of absorbable sutures include plain gut, chromic gut, polyglactin 910 (Vicryl, Ethicon, Inc.), polyglycolic acid (Dexon, Covidien), polydioxanone (PDS II, Ethicon, Inc.), poliglecaprone 25 (Monocryl, Ethicon, Inc.), polyglyconate (Maxon, Covidien), glycomer 631 (Biosyn, Covidien), and polyglytone 6211 (Caprosyn, Covidien). Suture material (both absorbable and nonabsorbable) can also be classified as monofilament or multifilament. Compared with multifilament materials, monofilament sutures have significantly less surface area. This can be a beneficial characteristic in a contaminated area where one wants to provide the least amount of surface area for bacterial colonization. Monofilament sutures have low friction and cause less tissue trauma; however, monofilaments are less pliable and have increased memory, making them somewhat more difficult to handle. The practical result of increased memory is that more throws are needed to create a secure knot. Examples of monofilament sutures include polydioxanone
487
(PDS II), poliglecaprone 25 (Monocryl), nylon (Ethilon), swage is where the suture material is attached to the and polyprolene (Prolene). Examples of multifilament suneedle. Two different processes during manufacturing tures: polyglactin 910 (Vicryl), polyglycolic acid (Dexon), are used to attach the suture material to the swage. polyester (Ethibond), and nylon (Surgilon). Channel swaging is a process in which a press creates a Numerous new suture varieties are available that can channel and the suture material is laid in the channel. be useful for specific tasks. However, one must keep in The swage is then crimped around the suture material. mind that with new technology comes new costs. For Drill swaging involves drilling a tunnel into which the flexor tendon repairs, looped suture material is placed. The Supramid (S. Jackson, Inc., EDUCATIONAL OBJECTIVES swage is then crimped ● Describe the categories of sutures based upon permanence and configu- around the suture. Alexandria, VA) suture has ration. gained popularity for use as a There are 2 main types core stitch. Another useful ● List the various uses of absorbable and non-absorbable sutures. of suture needle point: tavariety of suture that is avail- ● State the advantages and disadvantages of monofilament versus multi- pered and cutting. Tapered able as a loop is Fiberwire needles have a sharp point filament sutures. (Arthrex, Naples, FL). Fiber- ● List the difference between plain gut and chromic gut sutures. and a smooth body with no wire boasts the abilities of ● sharp edge. A tapered neeDiscuss the 3 basic parts of a suture needle. both monofilament and muldle works by spreading the Earn up to 2 hours of CME credit per JHS issue when you read the related tifilament. Its polyethylene tissue as it passes through core provides strength and articles and take the online test. To pay the $20 fee and take this month’s it. The sharpness of a tadurability against abrasion test, visit http://www.assh.org/professionals/jhs. pered needle is determined and its braided polyester by its taper ratio, typically jacket provides easier handling. Finally, Quill SRS (An8:1 or 12:1 (the higher the ratio, the sharper the giotech, Vancouver, BC.) is a variety of barbed suture tip). Typical uses of tapered needles include soft that can help strengthen wound closure. elastic tissue such as muscle or subcutaneous fat. Sutures are also classified by their size. The Suture material is less likely to cut through tissue familiar sizing nomenclature is a numeric value if a tract is made by a tapered needle. Traditionfollowed by a 0 (ie, 3-0). This is determined by the ally, tendon repair uses tapered needles; however, United States Pharmacopoeia rating system and Lam et al. found no biomechanical difference bebased on the breaking strength of the suture matetween tapered and cutting needles in tendon rerial, not the diameter. For example a 3-0 steel pair.4 suture has the same breaking strength as a 3-0 Cutting needles have a tip and 3 sharpened edges. nylon suture, but a much different diameter. Conventional cutting needles have the cutting surface on the inner curve. Unintended upward traction while NEEDLES working with a standard cutting needle may produce a shallow bite. This can create a weak point on the tract The suture needle consists of 3 basic parts. The point where the suture can cut through the tissue or skin. A begins at the tip and ends when the needle reaches its reverse cutting needle has the cutting surface on the full diameter. The body is the majority of the needle. It outer curve. Unintended downward pressure while begins where the tip ends and ends at the swage. The TABLE 1.
Suture Characteristics
Characteristic
Definition
Coefficient of friction
Suture’s relative resistance to being passed through a tissue. A higher coefficient of friction leads to increased local tissue damage. Monofilament usually has the lowest coefficient of friction.
Tensile strength
Suture’s ability to resist breakage. Strength of suture should not be significantly greater than the tissue it is approximating (if tensile strength is too high, suture will cut through tissue).
Elasticity
Suture’s ability to regain original length after deformation. Elasticity should be sufficient to accommodate tissue swelling.
Memory
Suture’s ability to return to original shape after deformation. Similar to pliability (more memory ⫽ less pliable and less knot security).
Cost
Significant issue in today’s health care arena. Newer suture materials with precision needles are generally more costly.
JHS 䉬 Vol A, March
In Brief
SUTURES AND NEEDLES
488
SUTURES AND NEEDLES
working with a reverse cutting needle may create deeper than intended tract. Both types of cutting needles are ideal for penetrating tough tissue such as skin. REFERENCES 1. Mosser SW. Sutures and needles. In: Janis JE, ed. Essentials of plastic surgery. St. Louis, MO: Quality Medical, 2007:13–19.
2. Marcus BC. Wound closure techniques. In: Baker SR, ed. Local flaps in facial reconstruction. Philadelphia: Mosby Elsevier, 2007:50 – 60. 3. Weinzweig J, Weinzweig NW. Plastic surgery techniques. In: Guyuron B, Eriksson E, Persing J, eds. Plastic surgery. Philadelphia: Saunders Elsevier, 2009:37– 44. 4. Lam WL, Garrido A, Vandermeulen J, Fagan MJ, Stanley PRW. Cutting or round-bodied needles for tendon repair. J Hand Surg 2003;28B:475– 477.
JOURNAL CME QUESTIONS Chemistry and Mechanics of Commonly Used Sutures and Needles What is the reduction in strength of monofilament and multifilament non-absorbable sutures? a. Monofilament and multifilament sutures retain their strength indefinitely. b. Monofilament sutures lose 15% to 20% of their tensile strength per year and multifilament sutures retain their strength indefinitely. c. Multifilament sutures lose 15% to 20% of their tensile strength per year and monofilament sutures retain their strength indefinitely.
d. Monofilament sutures lose 50% of their tensile strength per year and multifilament sutures retain their strength indefinitely. e. Monofilament and multifilament sutures lose 50% of their tensile strength per year. What percentage of absorbable suture strength is lost within 4 weeks of use? a. Less than 10% b. Less than 20% c. Less than 30% d. Less than 40% e. At least 50%
To take the online test and receive CME credit, go to http://www.assh.org/professionals/jhs.
In Brief JHS 䉬 Vol A, March