Recent advances in adipose tissue engineering research and technical refinements have reestablished the well-known lipofilling procedure.1 However, lipofilling procedures are essentially reversed tissue-restoring approaches, where cells are disrupted from their native niche through the process of liposuction and reinjected without any structural or nutritional support. The basic principles of adipose tissue embryology state that the extracellular matrix is a vector in cell development and behavior. It has been shown that more structurally stable fat grafts perform better.2 Logically, the lipoaspirate graft needs a matrix (injectable) that functions as a structural scaffold and prevents graft migration.
We present a patient involved in a traffic accident who sustained a degloving injury of the left knee. Initial treatment consisted of surgical débridement and coverage with a split-thickness skin autograft (meshed 1:1.5) impregnated with Tissucol (Baxter Healthcare Corp., Deerfield, Ill.) to enhance firm and equal take of the graft. Follow-up showed complete and consistent graft ingrowth, with no residual skin defects. There were no functional restrictions of the knee joint, but the patient complained about the aesthetically unpleasant prepatellar contouring defect. Clinical examination revealed tenderness on a palpable patella underneath the rigid skin graft caused by a lack of subcutaneous tissue.
To restore the natural characteristics of skin, a lipofilling procedure was proposed. Sixteen months after the initial trauma, the patient underwent lipoaugmentation of the prepatellar depression. Using the tumescent approach and a Coleman cannula, we obtained 110 cc of lipoaspirate, which was centrifuged for 3 minutes at 1000 rpm. The resultant fatty portions were homogenized in a 3:1 ratio with a commercially available filler, consisting of double–cross-linked hyaluronic acid. The addition of the filler to the lipoaspirate material was managed by connecting two Luer-lock syringes, one containing fat and one containing filler, with a two-way valve, displacing contents back and forth. A total of 67 cc of the mixture was then injected homogenously under the skin graft covering the knee.
Restoration of the prepatellar contour was obtained and smoothening of the skin graft was observed. Five months after the lipofilling procedure, a revision for excess skin resection was performed (Fig. 1). During this procedure, we were able to visualize the injected lipoaspirate material and take biopsy specimens for histologic analysis (Fig. 2). Normal vascularized adipose tissue depots were described, without evidence of fibrosis or necrosis.
We have used a double–cross-linked hyaluronic acid gel as a matrix for the fat graft. Hyaluronic acid is a major constituent of the physiologic extracellular matrix.3,4 The gel functions as a temporary scaffold, providing structural stability to the cells. The combination of the filler with the autologous cells could improve the clinical outcome, preventing migration and resorption of the fat graft in this challenging host area of great mobility. While the synthetic matrix is slowly resorbed, differentiating or existing adipose-derived stem cells can synthesize new extracellular matrix and reorganize the matrix into the mature form found in fat.5 This case report shows the efficacy of adding a protective matrix to lipoaspirate material to enhance the clinical outcome in lipofilling procedures.
Maarten A. J. Doornaert, M.D.
Phillip N. Blondeel, M.D., Ph.D.
Filip B. Stillaert, M.D.
Gent University Hospital
The authors have no commercial associations or financial disclosures that might pose or create a conflict of interest with information presented in this article.
1. Zuk PA. Tissue engineering craniofacial defects with adult stem cells? Are we ready yet? Pediatr Res.
2. Kononas TC, Bucky LP, Hurley C, May JW. The fate of suctioned and surgically removed fat after reimplantation for soft-tissue augmentation: A volumetric and histologic study in the rabbit. Plast Reconstr Surg.
3. Davidson JM, Nanney LB, Broadley KN, et al. Hyaluronate derivatives and their application to wound healing: Preliminary observations. Clin Mater.
4. Laurent TC. Biochemistry of hyaluronan. Acta Otolaryngol Suppl.
5. Nakajima I, Yamaguchi T, Ozutsumi K, Aso H. Adipose tissue extracellular matrix: Newly organized by adipocytes during differentiation. Differentiation
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