Large-Volume Fat Grafting: Identifying Risk Factors for Fat Necrosis.

Background: Fat necrosis is a well-recognized complication following autologous fat grafting. The purpose of this study was to evaluate the incidence of fat necrosis after large-volume fat grafting and identify risk factors for fat necrosis.

Methods: A retrospective review was performed on 83 consecutive patients who underwent large-volume fat grafting (>100 cc) to the breast performed by the senior author (L.P.B.) between September of 2011 and May of 2016. Fat necrosis was defined as palpable nodules, or nodules seen on imaging.

Results: A total of 148 breasts underwent 170 autologous fat transplantations. Indications included the following: 72 reconstructions after surgical therapy and 98 cosmetic augmentations. Mean age was 48 years, median graft volume was 300 cc, and median length of follow-up 423 days. Overall incidence of necrosis was 32.9 percent, with 47.8 percent in previously irradiated patients. Increased incidence of necrosis was associated with increasing fat graft volumes (OR, 1.002; p = 0.032), increasing body mass index (OR, 1.13; p = 0.04), and simultaneous implant exchange with fat ( p = 0.003). Fat grafting volumes greater than 450 cc in a single breast were also associated with an increase in fat necrosis ( p = 0.04). Within a group of six patients who had bilateral fat grafting with unilateral radiation therapy, there was a significant increase in necrosis on the irradiated side ( p = 0.015). In a cohort of non-BRAVA patients, reconstruction (compared to augmentation) was associated with fat necrosis ( p = 0.039).

Conclusions: Increased rates of fat necrosis were associated with volumes greater than 450 cc, patients undergoing concurrent implant exchange with fat grafting, and fat grafting after a history of lumpectomy or mastectomy without preexpansion. In addition, radiation therapy may be associated with a higher rate of complications.

Clinical Question/level Of Evidence: Risk, III.