The Architecture of Fat Grafting: What Lies Beneath the Surface

Background: Fat grafting is a powerful procedure limited by unpredictable volume loss. Grafted tissue survives via plasmatic imbibition until neovascularization occurs; therefore, fat that is deposited more than 0.2 cm from capillaries will undergo central necrosis. This study aims to determine the architecture of fat deposits within the recipient bed following fat grafting.

Methods: Fat was harvested by liposuction and stained with methylene blue. Stained fat was grafted into 4 × 4 × 2-cm sections of pannus tissue at graft-to-recipient volume ratios ranging from 1:10 to 1:1. Each tissue block was sectioned for stained graft visualization. The diameter of each deposit and the percentage with a radius greater than 0.2 cm were recorded.

Results: Average tunnel diameter was 0.20 ± 0.01 cm at a graft-to-recipient ratio of 1:10, 0.25 ± 0.01 cm at 1:8, 0.26 ± 0.01 cm at 1:6, 0.31 ± 0.01 cm at 1:4, 0.40 ± 0.01 cm at 1:2, and 0.57 ± 0.02 cm at 1:1. All comparisons reached statistical significance (p ≤ 0.05) except 1:8 versus 1:6 (p = 0.96). The percentage of fat parcels with a radius greater than 0.2 cm was 3.0 percent at 1:10, 5.3 percent at 1:8, 9.5 percent at 1:6, 20.9 percent at 1:4, 42.0 percent at 1:2, and 68.3 percent at 1:1. All percentage comparisons were significant except 1:10 versus 1:8 (p = 0.15).

Conclusion: As the total volume transferred increases, grafted deposits coalesce to form larger globules, particularly at ratios beyond 1:4, likely contributing to central necrosis and subsequent volume loss.

Clinical Question/level Of Evidence: Therapeutic, V.