The strength of microvascular anastomoses--an experimental evaluation in rats.

To determine the longitudinal strength of microvascular anastomoses during early healing, the left femoral arteries of 56 rats were divided and anastomosed with six interrupted sutures of 10-0 nylon. The right femoral arteries served as unoperated controls. The vessels were then harvested immediately, or 3, 7, 14, 21, 28, or 120-150 days after surgery. The cross-sectional surface area was measured and the force required to pull the vessels apart (burst strength) was determined with a tensiometer. Fifty-four of the 56 anastomosed vessels were patent at the time of harvest. All of the operated vessels ruptured at the site of anastomosis when the sutures pulled through the vessel wall. The mean burst strength of the anastomosed vessels was 44% of the contralateral unoperated controls immediately after surgery and did not significantly increase for four to five months. It was concluded that early mobilization of replanted parts is not limited by the strength of microarterial anastomoses.