Background:We previously reported that good surgical outcomes can be obtained with breast mold made by 3-dimensional printing. However, detailed breast shape is often difficult to create. Accordingly, we aimed to determine whether transplanting a flap and bioabsorbable mold in vivo would yield better results by retaining the flap shape inside the mold during the scar formation period.Methods:Vascularized adipose flaps were elevated in the bilateral inguinal region of male Sprague-Dawley rats (n = 7). A cone-shaped, bioabsorbable mold (LactoSorb mesh) was created using a template. On the experimental side, the flap was inserted into the mold and fixed. On the control side, a conical flap was created using absorbable sutures, based on a template.Results:The flaps were harvested 3 months postoperatively, and flap volume, base area, and projection were measured with 3-dimensional imaging. Volume and base area on the mold side tended to be smaller than those on the control side (P = 0.18 and 0.13, respectively) and close to the values of the template. In addition, the ratio of projection and base area value was significantly greater on the mold side than on the control side (P = 0.04). Histology revealed little inflammatory cell invasion, and scar tissue thickness around the flap showed no significant difference between the 2 groups (P = 0.76).Conclusions:This study demonstrated that soft-tissue morphology can be controlled to some extent with a bioabsorbable mold. Its clinical application in breast reconstruction requires further investigation.