Digit Replantation Practice: A Comparison of Three Rat Models

Digit replantation is a complex surgery that nearly always needs to be done as an emergency. As such it is often difficult to teach. Several models have been developed to train surgeons in this procedure. We compare three rat models of replantation with the aim of ascertaining which most simulates the digit replantation. Inbred albino rats were selected and divided into three groups of 13 each, tail, penile, and hind replant groups. Three rats in each group were anesthetized, the specific amputation injury is created and is replanted for the anatomic component of the study. For the comparative section, 10 animals were anesthesized and the amputated parts were replanted under standard conditions. The parameters measured included weight, vessels and nerve diameters, method of fixation, total ischemia and replant times, the patency rates (after operation and at one week post surgery), as well as postoperative complications. All rats survived in the procedure. There was patency in all groups immediately. Rat tail group had 90%, penile group 100%, and hind limb group 90% survival 1 week after the replantation. There was one mortality in the hind limb group. The penile replant group was the shortest ( p  < 0.001), and all vessel sizes were comparable except the central artery of the tail which was significantly smaller ( p  < 0.001). The processes of the hind limb group most simulated the human digit replant procedure, though the ischemia and total replant times are significantly longer ( p  < 0.005). Though the immediate and 1 week patency rates were similar in all three groups, the hind limb replantation model involved steps most similar to human digit replant surgery and is recommended as the preferred teaching model.