The influence of diabetes on free flap transfer: I. Flap survival and microvascular healing.

Although recent clinical case presentations suggest that diabetes does not predispose free tissue transfers to increased risk of failure, this remains an open question. The present study used a syngeneic rat strain (Lewis) for free groin flap transplantations between normal rats and streptozotocin-induced diabetic rats (2 months' duration of symptoms), to investigate the influence of diabetes on flap transfer. Flap survival at 1 week, vascular patency, flap histology and ultrastructure, and scanning electron microscopy of anastomotic sites and of corrosion casts of flap vasculature were used as bases for comparison. No differences were found in comparisons of flap survival between any groups of transfer combinations (normal flap onto normal recipient, diabetic flap onto normal recipient, normal flap onto diabetic recipient, and diabetic flap onto diabetic recipient); 100% success was achieved in each group. No differences were found in histology or corrosion casts. Transmission electron microscopy revealed a thickening of the capillary basement membrane in rat diabetic skin after only 8 weeks of symptoms. This ultrastructural finding is consistent with similar capillary basement membrane thickening seen in many other tissues of short- and long-term diabetic animals and humans. Re-endothelialization across the arterial anastomosis at 2 weeks postoperatively was significantly faster in normal versus diabetic animals (p less than 0.05). The predominantly negative findings of this study support the application of free flap transfers in diabetic patients. It is concluded that reconstructive efforts involving free tissue transfer may not be contraindicated in diabetic patients.