Influence of age on free flap tolerance to ischemia: an experimental study in rats

Free tissue transfer and extremity replantation have been successfully performed in elderly patients. However, it is not known whether such procedures have an associated higher risk of failure in this patient population, nor is it known whether prolonged ischemia exacerbates the problem. This study used a senescent rat model to address these issues. Free groin flaps were raised in the syngeneic Lewis rat strain, using the following three age groups: young (2-3 months old), middle-aged (10-12 months), and old (20-22 months). Flaps were transferred to the groins of young recipients after a 72-hour period of cold (4 degrees C) ischemia. Survival was followed for 7 days; 58% of the young flaps survived, whereas 42% of the middle-aged and only 26% of the old flaps survived. These differences achieved significance in comparing survival of young versus old flaps (p < 0.03). These results support the practice of free flap reconstruction in elderly patients, but suggest that there is less tolerance to prolonged ischemia with increasing age.