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How to knot bury and not break the suture: the 3-1-bury-1 knot

Published:April 09, 2019DOI:https://doi.org/10.1016/j.jcjo.2019.02.014
      Suturing of a wound is typically performed for incisions that fail to seal after stromal hydration or after other anterior segment procedures, such as penetrating keratoplasty.
      • Ong-Tone L.
      • Bell A.
      • Tan Y.Y.
      Practice patterns of Canadian Ophthalmological Society members in cataract surgery: 2011 survey.
      • Leaming D.V.
      Practice styles and preferences of ASCRS members—2003 Survey.
      • Narváez J.
      • Jones J.
      • Zumwalt M.
      • Mahdavi P.
      Reversed needle pass clear-corneal or limbal incision suturing technique using the 3-throw (1-1-1) adjustable square knot.
      • Lutchman C.R.
      • Leung L.H.
      • Moineddin R.
      • Chew H.F.
      Comparison of tensile strength of slip knots with that of 3-1-1 knots using 10-0 nylon sutures.
      On tying a suture of appropriate tension, rotation and burying of the knot is important to prevent foreign body sensation and irritation to the palpebral conjunctiva.
      • Narváez J.
      • Jones J.
      • Zumwalt M.
      • Mahdavi P.
      Reversed needle pass clear-corneal or limbal incision suturing technique using the 3-throw (1-1-1) adjustable square knot.
      • Lutchman C.R.
      • Leung L.H.
      • Moineddin R.
      • Chew H.F.
      Comparison of tensile strength of slip knots with that of 3-1-1 knots using 10-0 nylon sutures.
      • Henry C.R.
      • Flynn Jr, H.W.
      • Miller D.
      • et al.
      Delayed-onset endophthalmitis associated with corneal suture infections.
      • Johnson A.J.
      • Stulting R.D.
      Knot-tying principles and techniques.
      However, the knot can break or slip during rotation and burying of the knot.
      The 3-throw, “3-1-1” approach, also known as the surgeon's knot, is a traditional suture tying technique employed routinely in ophthalmology.
      • Johnson A.J.
      • Stulting R.D.
      Knot-tying principles and techniques.
      However, when tied, this knot typically has a cross-sectional area significantly larger than its accompanying needle tract. As a result, a surgeon may have difficulty burying the knot into the corneal stroma or limbal tissue. The force required to bury this knot may exceed the tensile strength of the suture, leading to suture breakage. Some alternatives, such as the “3-1”, the “2-1-1” square knot, the “1-1-1” slip knot, and “1-1-1-1” modified slip knot, have been used.
      • Narváez J.
      • Jones J.
      • Zumwalt M.
      • Mahdavi P.
      Reversed needle pass clear-corneal or limbal incision suturing technique using the 3-throw (1-1-1) adjustable square knot.
      ,
      • Johnson A.J.
      • Stulting R.D.
      Knot-tying principles and techniques.
      • Rana M.
      • Savant V.
      • Prydal J.
      A study of slippage of various knot configurations.
      • van Rijssel E.J.C.
      • Baptist Trimbos J
      • Booster MH
      Mechanical performance of square knots and sliding knots in surgery: a comparative study.
      These techniques reduce the size of the knot and, in the case of the slip and modified slip knot, allow adjustment of suture tension until locked.
      • Narváez J.
      • Jones J.
      • Zumwalt M.
      • Mahdavi P.
      Reversed needle pass clear-corneal or limbal incision suturing technique using the 3-throw (1-1-1) adjustable square knot.
      However, these knots tolerate significantly less tensile force. For instance, in one study, the modified slip knot tolerated 0.64 N before breakage and 0.37 N before slippage, whereas the surgeons knot tolerated 0.71 and 0.48 N, respectively.
      • Lutchman C.R.
      • Leung L.H.
      • Moineddin R.
      • Chew H.F.
      Comparison of tensile strength of slip knots with that of 3-1-1 knots using 10-0 nylon sutures.
      In another study, the slip knot and modified slip knot demonstrated greater than 2 times more slippage after 24 hours than the surgeon's knot.
      • Rana M.
      • Savant V.
      • Prydal J.
      A study of slippage of various knot configurations.
      Herein, we present an alternative technique for tying a 3-1-1 square knot, reducing its cross-sectional area while burying the knot, thus reducing the likelihood of suture breakage.
      A 10-0 nylon suture is placed across the wound (Video 1). The first throw comprises 3 loops and may be adjusted to the desired tension (Fig. 1A,B). The second throw uses 1 loop in the opposite direction to the first throw. This creates a locking square knot (Fig. 1C,D). The knot is buried (Fig. 1C,D). The third and final throw is a single loop that is tied in the opposite direction to the second throw to lock the knot securely (Fig. 1E). The ends of the sutures are then trimmed using a 75-blade. The final step pulls the knot from its buried position but may be buried once again with relative ease (Fig. 1F).
      Fig 1
      Fig. 1The suture is passed in a cornea-to-scleral or scleral-to-corneal direction through the wound. (A) The first throw is made forward with tying forceps between the 2 ends of the suture with 3 loops made in the same manner as the traditional 3-1-1 technique. (B) The short end of the suture line is then pulled through the loops in the opposite direction and the knot set to the desired tension. (C) The second throw is made with a single loop and (D) tightened to lock the knot. (E) Using forceps, the knot is rotated and (F) buried. (G) The final throw is made with 1 loop. (H) This will unbury the knot (I), which is then reburied.
      In the traditional 3-throw, 3-1-1 technique, the initial loops limit the suture from slipping, permitting the appropriate tension to be maintained during the second and third throws, each of which secures the knot further. This ultimately results in a strong knot that is resistant to breakage and unravelling. However, this technique has its disadvantages, including appropriate tensioning and its large size, making it more difficult to bury.
      Attention must be made to bury all corneal and limbal knots to reduce corneal irritation. For these reasons, smaller knots have been developed (e.g., 3-1, 2-1-1 square knots, the 1-1-1 slip knot, and 1-1-1-1 modified slip knot). Each of these techniques produces a smaller knot that requires less force when burying.
      • Lutchman C.R.
      • Leung L.H.
      • Moineddin R.
      • Chew H.F.
      Comparison of tensile strength of slip knots with that of 3-1-1 knots using 10-0 nylon sutures.
      • Rana M.
      • Savant V.
      • Prydal J.
      A study of slippage of various knot configurations.
      • van Rijssel E.J.C.
      • Baptist Trimbos J
      • Booster MH
      Mechanical performance of square knots and sliding knots in surgery: a comparative study.
      The slip knot and modified slip knot in particular offer the additional benefit of tension adjustment until after the third throw. The trade-off, however, is that these alternatives produce sutures with reduced tensile strength compared with the traditional 3-1-1 technique.
      • Lutchman C.R.
      • Leung L.H.
      • Moineddin R.
      • Chew H.F.
      Comparison of tensile strength of slip knots with that of 3-1-1 knots using 10-0 nylon sutures.
      • van Rijssel E.J.C.
      • Baptist Trimbos J
      • Booster MH
      Mechanical performance of square knots and sliding knots in surgery: a comparative study.
      In the 3-1-bury-1 technique, the cross-sectional area of the knot is smaller after the second throw than that of the standard 3-1-1 knot. This reduced cross-sectional area allows the knot to be more easily rotated into the corneal stroma. This initial burying of the knot enlarges the suture needle tract. During the subsequent throw, the knot retracts from the corneal stroma but is easily rotated back into the previously widened path, thus minimizing the potential for suture breakage. Ultimately, this may limit the need to replace sutures, decrease operating time, and reduce associated complications.

      Footnotes and Disclosure

      Adam P Deveau: none; Mark E Seamone: none; Darrell R Lewis: none; R. Rishi Gupta: none.

      Appendix. Supplementary materials

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