Physical Characteristics of Suture Material

   
 
Table 6-15 Physical Characteristics of Suture Material
 Physical CharacteristicDefinitionComment
 
Coefficient of friction (COF)
Ease with which suture will pull through tissue
Polypropylene slides easily (↓ COF) Knot strength directly proportional to COF (↑ knot strength with ↑ COF)
 
Suture configuration
Monofilament – single strand
(nylon or polypropylene)

Multifilament – made of several strands either twisted or braided
↓ Coefficient of friction (COF) so slides easily through tissue causing less trauma
 
Handle/tie more easily, ↑ tensile strength, but ↑ COF, ↑ risk infection (organisms may be harbored between filaments)
 
Capillarity
Ability of suture to absorb and transfer fluid
Multifilament has ↑ capillarity, which also increases risk of harboring bacteria
 
USP size
Diameter of suture material

{Choose smallest suture providing adequate tensile repair}
Related to tensile strength (smaller the number, greater tensile strength/diameter)
 
Elasticity
Ability of suture to regain former shape (original size/shape) after being stretched
↑ Elasticity means suture can stretch with tissue and will recoil when swelling subsides
 
Knot strength
Security of tied knot and degree of slippage occurring in a knot
Polyglycolic acid has one of highest knot strengths
 
Memory
Suture’s tendency to retain natural configuration after deformation (determined by elasticity and plasticity of material)
High memory sutures like polypropylene and nylon have greater tendency to untie themselves (do not handle easily, lower knot strength requiring greater number of ties); silk w/ ↓ memory (rarely unties)
 
Plasticity
Ability of suture to retain new length and form after being stretched
Important in tissue edema – as sutures with plasticity (polypropylene) will accommodate edema without cutting into tissue; ↑ plasticity may lead to ↑ knot security
 
Pliability
How easily suture can be bent
Braided suture (silk) most pliable
 
Tensile strength
Force required to snap the suture (determined by diameter and composition of suture)
Larger sutures usually have more tensile strength; synthetic material usually stronger than natural materials like silk
 
Tissue reactivity
Degree of inflammation elicited by placement of suture in wound (degree of foreign body reaction)
Natural suture w/ ↑ inflammatory response vs. synthetic materials (nylon); ↑ suture diameter w/ ↑ tissue reaction; ↓ reactivity with monofilament (unlike multifilament)
 
Absorption
Absorbable sutures lose tensile strength over time by absorption
Proteolysis – natural materials (cat gut or silk)
Hydrolysis – synthetic absorbable sutures