Effects of methylprednisolone on the viability of experimental flow-through venous flaps

In this study, the effects of a corticosteroid, methylprednisolone, on the survival of flow-through venous flaps were investigated in rabbits. Flow-through venous flaps, sized 3.0 x 4.5 cm, were raised in the rabbit-ear model. Animals were randomly distributed into three groups, and 30 flaps were raised as follows: Group 1 (n=10): control flow-through venous flaps (intramuscular saline injection 2 ml/d); Group 2 (n=10): flow-through venous flaps with daily intramuscular methylprednisolone injection (30 mg/kg/d); and Group 3 (n=10): negative control composite grafts with the flow-through vein ligated at both edges of the flap. All injections were done 24 hr and 1 hr preoperatively, and for 5 days postoperatively. Observations included gross and histologic examination, and percentage of survival of the flaps on the tenth day. Venous flaps of the animals receiving daily methylprednisolone injections (Group 2) were noted to have statistically significantly improved flap survival ( p<0.05), compared to the control group (Group 1). Flaps in Groups 1 and 2 demonstrated significantly higher survival rates, compared to the composite grafts ( p<0.01). Histologic examination of methylprednisolone-treated animals showed normal stratified squamous epithelium, while complete necrosis was noted in the composite grafts. Untreated flow-through venous flaps demonstrated patchy epidermal sloughing, crusting, and partial necrosis. These results suggest that the survival of potentially ischemic flow-through venous flaps can be enhanced in rabbits by daily methylprednisolone treatment in the perioperative period. Increased tolerance to ischemia and modulation of venous flap microcirculation might be possible mechanisms for this salutary effect.