Effect of radiation on skin expansion and skin flap viability in pigs

The aim of the present study was to investigate the effect of radiation tre atment both on skin tissue expansion with the chronic inflation of subcutan eous expanders and on skin flap viability in surgically delayed and expande d skin in the pig. One flank in each of sis pigs (initially weighing 17 +/- 1.8 kg) was randomly assigned for radiation treatment, and the contralater al flank served ass a nonirradiated control. Three mirror-image, 8 x 10-cm, rectangular templates were marked on each flank; these templates were rand omly assigned to the construction of a delayed skin flap (group A), a skin flap raised on expanded skill (group B), or a skin flap raised on expanded skin with a capsulectomy before flap surgery (group C). Radiation treatment was performed using sequential radiation with three fractions per week (81 0 cGy/fraction) for 2 weeks, with a total dose of 4860 cGy. Twelve weeks af ter radiation treatment, skin expanders (8 x 10 cm) were installed subcutan eously in the locations assigned for skin expansion. Skill expansion by the inflation of subcutaneous skin expanders with saline twice weekly was star ted 8 weeks later and lasted for 3 weeks. Two weeks after surgical delay an d the last skin expansion, 8 x 20 cm skill flaps were raised on the locatio ns assigned for delayed skin flaps, expanded skin flaps, and expanded skin flaps with a capsulectomy. Skin flap viability was assessed 24 hours later using a fluorescein dye-staining technique. Skin expansion by the inflation of subcutaneous expanders with saline was slower (p < 0.05) in the radiate d skin (39 +/- 6 ml/filling) than in the nonirradiated control skin (51 +/- 6 ml/filling). Radiation reduced the overall area of expanded skin by 23 p ercent (p < 0.05) compared with the control. Radiation treatment also reduc ed skin viability by 36 percent ( P < 0.05) in the delayed skin flaps, 27 p ercent (p = 0.10) in the expanded skin naps, and 36 percent (p < 0.05) in t he expanded skin flaps with a capsulectomy when compared with their contral ateral, nonirradiated controls. There were no significant differences in sk in viability among these three types of skin skin flaps within the radiated and nonirradiated groups. Taken together, these observations indicate that radiation treatment reduced the effectiveness of the surgical delay proced ure, the amount of subcutaneous skin expansion (by an increase in skin area ), and skin flap viability. However, a capsulectomy alone did not affect th e viability of skin flaps raised on expanded skin.