Healing of experimental colonic anastomoses: II. Breaking strength of the colon after left colon resection and anastomosis

Abstract

Mechanical strength of the left colon with anastomosis and the intact transverse colon was studied by breaking strength tests performed from four to twenty-eight days after standardized left colon resection in the rat. Two different single layer inverting suture technics were used, continuous and interrupted. Breaking strength of the colon in unoperated rats paralleled to a certain extent the collagen concentration of the colonic wall, with highest values of strength in the left colon where collagen concentration is highest. Both types of anastomoses showed a rapid and equal gain in strength between days 4 and 10, after which time the increase in strength occurred at a much slower rate. After ten days the anastomosis had gained approximately 50 per cent of the strength of the left colon in unoperated control rats. Four weeks after the operation the anastomoses made of continuous suture had reached 75 per cent of normal breaking strength and were significantly stronger than those made of interrupted sutures, which had gained only about 55 per cent of normal strength. Breaking strength test measured the strength of the anastomosis throughout the four week period of investigation, since the rupture always occurred in the anastomotic line. Breaking strength determinations of the intact transverse colon did not show any alterations from normal during the healing course as did determinations of bursting strength reported in a previous study. In skin wounds breaking strength showed a constant development of strength during the four week investigation period, while the gain in strength of the anastomosis slowed down after ten days, although it had only reached 50 per cent of normal.