Inclusion and exclusion criteria

The inclusion criteria were: (1) articles reporting on adult patients that received facial fat grafting for esthetic purposes; (2) articles in which the researchers used 3D surface analysis systems to evaluate the volumetric measurements and fat graft retention rate during follow-up; (3) articles that reported follow-up periods of at least 3 months; (4) explicit data including injection volumes and fat graft retention rates were reported; (5) prospective and retrospective clinical trials, observational studies, and case series with sample sizes larger than 10; and (6) trials or case series including normal-sized fat grafts without cell-assisted lipo-transfer (CAL).

The exclusion criteria were: (1) review articles and animal studies; (2) articles that studied fat graft retention for purposes other than esthetics (eg, trauma, scars, congenital disorders); (3) articles that used ultrasound, CT, or MRI for volumetric measurements; and (4) articles that reported follow-up periods of <3 months.