The Linear Retrograde Infiltration (LiRi) Technique for Buttock Fat Infiltration: A Cohort Evolution

Autologous fat grafting in the buttocks has gained great popularity However, one of the main risks is infiltration of fat into the systemic venous system, leading to potential complications such as macroscopic fatty embolism (MAFE), which can be fatal.

This study evaluated the safety and efficacy of the LiRi (Linear Retrograde infiltration) for autologous fat grafting in the buttocks, and its evolution over a six-month follow-up period.

The procedure was performed in 114 patients. The technique used strict ultrasound guidance with a 4-5 mm basket cannula or a cannula with 4 crosshead holes. The cannula was placed in the deep subcutaneous space, and its path was confirmed with ultrasound to avoid penetrating the deep gluteal fascia. Once confirmed, the ultrasound was removed, and fat was infiltrated retrogradely.

A minor complication rate of 7% was observed, consisting of fat cysts (7%), asymmetries (5%), contour irregularities (2%), and fat necrosis in one case, with no infections or fat embolisms. Statistical analysis showed no significant correlation between complications and variables such as BMI or the total volume of infiltration.

The results suggest that the LiRi technique is safe and effective for gluteal augmentation, demonstrating consistent fat integration and minimal complications, although further long-term research is recommended to confirm these findings.