The effects of the number and ratio of repaired arteries and veins on the survival rate in digital replantation.

From January 1990 to December 1998, 631 consecutive single-digit replantations were reviewed retrospectively to determine the essential number of vascular anastomoses and the artery-to-vein ratio for successful finger replantation. The correlations between the number and the ratio of anastomosed vessels and the survival rate were examined according to the amputated digital levels, and all of the correlated results were compared with each other statistically. In zone I, the survival rate of the digits with a vein repaired was higher than that of digits treated with the external bleeding method. In zone II, repairing more arteries than veins led to venous congestion and resulted in a failure of replantation. Thus, the ratio of an equal or greater number of veins repaired to the arteries repaired was an important factor in successful replantation in zone II, which may be due to the large amount of arterial input relative to the small volume of venous drainage via small veins in the replanted digit. In zone III, the equal number of arteries and veins repaired was also an important factor in successful replantation. However, unlike zone II, even when more arteries were repaired than veins, venous congestion occurred rarely because the vein in this area was larger, providing sufficient venous drainage. In zone IV, repair of two veins was needed to yield good results. Because the volume of the amputated part in zone IV was larger than in other zones, it was desirable to repair both arteries, even though repairing one artery yielded good results. In conclusion, it is desirable to repair as many vessels as possible to increase the possibility of a good result. However, digital amputations and their conditions for replantation differ. Therefore, the number and ratio of vessels that need to be repaired should be modified and adjusted in each case.