A biochemical and histological comparison of vascularized and free fat grafts in the rabbit

An experimental study, in 20 rabbits, of free (i.e., nonvascularized) versus vascularized fat tissue transfer was undertaken. The purpose was to study the biochemical and histological changes in the two types of fat grafts compared with normal fat tissue over a period of 16 weeks. The left inguinal fat pad was transferred freely to the contralateral side; the right inguinal fat pad was transferred to the left side where the pedicle was anastomosed to the left femoral artery and vein. Macroscopically, at all postoperative times, the transferred free fat had a harder consistency, was more adherent to the surroundings, and was less pliable than the vascularized fat, which was similar to normal fat. Histologically, free fat tissue displayed near complete degeneration at 2 and 4 weeks, but recovered to essentially normal appearance by 16 weeks. Apart from some degeneration evident at 2 weeks, vascularized fat tissue retained a normal histological appearance to 16 weeks. Biochemical analysis demonstrated minor increases of collagen deposits in free fat grafts, but negligible changes were observed in the vascularized fat grafts. Free fat grafts were significantly dehydrated relative to the vascularized fat grafts and control fat (p < 0.01). Based on these findings, we suggest that the clinical use of vascularized fat tissue transfer would be preferable in most circumstances to free fat transfer.