Scanning electron microscopic study of monofilament suture knots.

Abstract

Aims/Background-Interrupted corneal sutures are used routinely by many cataract and corneal surgeons. A slim compact knot facilitates burial and allows atraumatic suture removal, with decreased risk of wound dehiscence. The size and morphology of knots tied in different configurations were investigated. Methods-10-0 nylon suture material was used to tie knots on porcine corneal cataract sections using 2/1/1 (reef and granny), 3/1/1, and 1/1/1/1 (slip knot) configurations. 10-0 Mersilene was used to tie 2/1/i reef knots. Scanning electron micrographs of the knots were digitised and their maximal lengths and widths estimated. In addition, the area of each knot was calculated and used as an index of its volume. Results-21111 reef knots were significantly smaller in all dimensions compared with the other knots (all p<0.03) except for the maximal width of 2/i/l granny knots which were no wider than the 2/i/l granny knots. The Mersilene knots were larger than the nylon ones. Conclusion-The use of 2/i/l reef knots is recommended for corneal suturing. (Br_' Ophthalmol 1996; 80: 164-167) Materials and methods Corneal sections were performed on porcine eyes by a single surgeon (CSCL), and sutured using interrupted monofilament sutures. The sutures used were 10-0 nylon (Alcon Laboratories UK, Watford) and 10-0 polyester (Mersilene; Ethicon). The suture knots were then buried into the cornea, cut and removed, and mounted in a similar orientation for scanning electron microscopy. Four different knot configurations with the nylon monofilament were assessed: a 2/1/1 reef (square) knot, a 2/1/1 granny knot, a 3/1/1 reef knot, and a 1/1/1/1 slip knot, and five examples of each type of knot were examined in order to reduce variability. Five knots were tied using the 10-0 Mersilene in a 2/1/1 reef knot configuration.Following scanning electron microscopy, the knot micrographs were digitised on a digitising tablet by a masked observer (WYC) and estimations of their size calculated. For each knot the maximal knot width at 90 degrees to the suture orientation in the cornea, and the maximal length along the suture were measured, as well as knot area. All knots were scanned at the

Suturing techniques and postoperative management in penetrating keratoplasty in the United Kingdom

“…Hammond et al demonstrated with electron microscopy that a 2-1-1 nylon reef knot was a slim knot that allowed easier knot burial and atraumatic suture removal, thus reducing the risk of wound dehiscence. 15 The way in which the knots are buried can determine how easily they can be removed later on. It is generally undesirable to drag the knot through the graft–host interface, and we would recommend that the knots should not be buried at the interface.…”

Stitched up: full thickness corneal grafts

“…The suture knot is believed to be the most irritant part of the suture and offers the greatest impediment to suture burial. A 2/1/1 nylon reef knot has been shown to produce the smallest knot size4 with consequent ease in burial. We have preferred a 3/2/1 configuration, which gives a leading arrowhead configuration to facilitate burial.…”

“…They induce minimal torsion of the graft and allow for selective removal to manage postgraft astigmatism. However, if tied with differing tensions, they can induce more astigmatism, and the larger number of knots can be detrimental as stated above 4 – 7…”