Abstract
The clinical success of limb replantation and tissue transfer is partly dependent on the duration of ischemia experienced by the amputated part. This study focused primarily on the damage that occurs during this ischemic period. An experimental system was implemented that allowed the observation of contractile function in totally isolated skeletal muscle after ischemia. Contractile function was selected as an indicator of ischemic damage because normal function is the ultimate goal of replantation. All experiments were performed on the rat extensor digitorum longus. The muscles were subjected to ischemic periods of 1.5, 3.0, and 5.0 hours and were stored in either a hypothermic (4ยฐC) or a roomโtemperature (23ยฐC) environment during the ischemic interval. After the ischemic period, all muscles were transferred to a tissue bath and were subjected to contractility testing, followed by fatigue testing. In both groups, muscle function decreased as the ischemic interval was increased. A significant difference in function between the normal control and the muscles of both ischemic group implied that ischemic injury had occurred in the hypothermic and roomโtemperature muscles, even with the relatively short 1.5โhour ischemic interval. After each ischemic interval, however, the hypothermic muscles produced significantly greater contractile force than the roomโtemperature muscles in both the contractility and the fatigue tests. After 1.5 hours of ischemia, the contractile force in the hypothenic group was about three times as great as that observed in the roomโtemperature group. These results indicated that muscle function after a period of totally isolated ischemia is protected by hypothermic preservation. They also support the advisability of storage of amputated parts and free muscle flaps in hypothermic environments before replantation, even after relatively brief intervals of ischemia.