Tissue reaction and surgical knots: the effect of suture size, knot configuration, and knot volume.

Tissue reaction surrounding surgical knots was assessed histologically using a semiquantitative scoring system in 40 male Wistar rats. We tested sizes 2/0 and 4/0 (United States Pharmacopeia [USP]) coated polyglycolic acid and coated polyglactin-910 sutures, and two different knots. In addition, we measured the volume of the different knots and the total volume of tissue reaction surrounding the knots. Multivariate analysis showed only suture material and suture size to be independent factors determining tissue reaction. An increase of suture size resulted in a more than four- to sixfold increase in knot volume and a more than two- to threefold increase in the amount of the tissue-reaction sheath; however, the addition of extra throws to the knot enlarged the knot body by a factor of ony 1.5 and the tissue-reaction sheath by a factor of 1.0-1.9. These findings suggest that the use of thick-gauge suture material adds much more to the total amount of foreign body and tissue reaction in the wound than the addition of extra throws to the knot and might, therefore, be deleterious to optimum wound healing.