A classification system for fat necrosis in autologous breast reconstruction

Fat necrosis (FN) is a common complication of autologous breast reconstruction, yet no classification system exists to describe it. We sought to develop and validate a tool for meaningful reporting, comparison of techniques, and treatment planning. Our hypothesis was that a valid classification system would demonstrate higher grades of FN for pedicled transverse rectus abdominus myocutaneous (pTRAM) flaps as compared to free flaps (FF).

A classification system for FN was developed: grade I, radiologic evidence only; grade II, palpable but not visible FN; grade III, palpable and visible FN; and grade IV, symptomatic FN. For validation, we applied this system to patients who had undergone pTRAM flaps from 2002 to 2006 and FF from 2006 to 2010 at our institution.

We performed 93 pTRAM flaps in 69 patients and 102 FF in 69 patients. One patient had grade I FN and was observed. Of the 29 patients with grade II FN, 48% were observed, 17% had biopsy, and 35% underwent debridement. Of the 9 patients with grade III FN, 11% underwent biopsy and 89% had debridement. All patients with grade IV FN underwent debridement. The distribution of FN differed between pTRAM and FF. The mean FN grade for patients undergoing pTRAM was 1.4 versus 0.4 for those undergoing FF (P < 0.05). Fat necrosis requiring reoperation was more frequent in the pTRAM group (23.7% vs 5.9%, P < 0.05).

Our validation study confirmed that FN grade was associated with the need for surgery and was higher for pedicled flaps as compared to FFs. As it is similar to the Baker grading system for capsular contracture, this classification system is familiar to all plastic surgeons. It is simple, easy to remember, clinically oriented, and could be readily incorporated into outcome studies of autologous breast reconstruction.