Fatty tissue atrophy of free flap used for head and neck reconstruction

Many investigators have reported that microsurgical transplanted muscle shows a reduction in volume; however, changes in the size of transplanted fatty tissue have not been studied. The purpose of this study was to describe the degree of fatty tissue atrophy of microsurgical flaps.

Nineteen patients who underwent head and neck reconstruction using free flaps between 2003 and 2008 were available for this study. They were divided into an irradiated (8 patients) and nonirradiated (11 patients) group. The free flaps used for reconstruction were rectus abdominal musculocutaneous, anterolateral thigh fasciocutaneous, and forearm flaps. This retrospective study utilized radiographs of magnetic resonance imaging or computed tomography, which were taken two to three and after six months postoperatively. The fatty tissue thickness of free flaps in each magnetic resonance imaging or computed tomography slice was measured. The transplanted fatty tissue thickness of the flap after more than six months was compared with the change in the normal fat thickness of the same slice, to avoid any bias caused by a change in diet due to the general postoperative condition.

The thickness of transplanted fatty tissue tends to decrease over period of 6-10 months after surgery. In the nonirradiated group, the mean postoperative fatty tissue thickness change in the free flaps was decreased by 15.9% (range, 0.3-31.4%). In the irradiated group, this change in the free flaps was decreased by 20.9% (range, 2.3-39.4%).

Fatty tissue in free flaps shows atrophy over a period of six to nine months after surgery, and irradiation is more likely to result in severer fatty tissue atrophy.