Technical considerations in knot construction. Part I. Continuous percutaneous and dermal suture closure

Assessment of knot security in continuous intradermal wound closures

“…Knot security of the chain-stitch knot appeared superior to the square knot, as no slipping was noted. Given these observations and the results of previous studies that have shown poorer knot security and increased knot volume when comparing the square and chainstitch knots [4,8], as well the historic observations that square and surgeon's knots created with the penultimate loop are particularly prone to slipping [1,7]; the chain-stitch knot may be superior to the square knot as a termination knot in continuous suture closures. The lower volume of the chain-stitch knot may also be advantageous clinically when placed in the subcuticular layer, as a large knot may cause problems with inflammation, patient discomfort [12], and alter the cosmetic appearance of the closure.…”

“…Properly formed square knots can be converted into a series of half-hitches when uneven tension is applied to the suture ends, particularly with monofilament materials [8]. The square knot has been shown to be prone to failure by slipping [6], especially when the penultimate loop is incorporated in a square knot, as in the termination of a continuous suture line closure [1,7]. Depending on the suture material and size used, square knots have been shown to require an additional two to three throws on top of the initial knot (four to five throws total) to produce a secure knot [7].…”

“…The square knot commonly used to start and complete a suture line is bulky, requiring four to six throws to form a secure knot for most suture materials [1,6]. This can result in a knot that may protrude to the surface and cause problems with wound healing, excess patient discomfort, and sub-optimal cosmetic appearance in subcutaneous and subcuticular closures [11].…”

Enhancing knot security by heat treatment of knot ears

“…The ears are the cut ends of the suture, which add security to the knot by preventing untying during slippage. 4 A square knot is formed by two single throws in which the right ear and loop come out in a position that is directly opposite to that of the left ear and loop. The ear and loop on the same side must be parallel to each other.…”

“…4 Knots were tied around a plastic mandrel. After knot construction, ears were trimmed to 3 mm, and the loop around the mandrel was then divided at its midportion, after which its cut ends were positioned between the clamps of the Instron Tensile Tester.…”