Cannula Size Effect on Stromal Vascular Fraction Content of Fat Grafts

Fat is an active and dynamic tissue composed of adipocytes supported by a structural framework known as the stromal vascular fraction (SVF). SVF is traditionally isolated by enzymatic processing, but new methods are being investigated to isolate it mechanically. Recent studies propose that fat harvested with larger cannulas has a higher survival rate, most likely due to a higher concentration of SVF.

Lipoaspirates were obtained from 10 patients who underwent elective liposuction using a 5-mm and a 1-mm cannula attached to a syringe using standard pressure. The fat was aspirated from the same area at adjacent sites. An estimated 5-mm fat particles were also cut down to 1-mm using a micronizer (Marina Medical). A 5-cm³ volume of each sample was compressed through a 0.5-mm opening strainer and rinsed with normal saline to extrude the oil. The resultant SVF left on the strainer was then measured in a 1-cm³ syringe.

The volume extracted from a 5-mm cannula (mean, 0.23 cm³; SD, 0.10) versus a 1-mm cannula (mean, 0.11 cm³; SD, 0.06) was statistically significant (P = 0.009). An H&E-stained slide from the SVF was obtained for confirmation. Finally, 5-mm fat particles cut down to 1-mm particles using the micronizer resulted in an average volume of 0.20 cm³, which was higher than the average volume harvested with a 1-mm cannula.

Harvesting with a 5-mm cannula resulted in significantly more SVF than harvesting with a 1-mm cannula. Resizing fat particles harvested with a larger cannula down to 1-mm resulted in higher SVF than SVF obtained with a 1-mm cannula directly.