Assessing Risks in Intramuscular Fat Grafting: A Systematic Review and Meta-Analysis of Complications

Intramuscular fat grafting to enhance muscle volume and definition has gained popularity in plastic surgery. However, the safety and standardization of this technique remain controversial. This systematic review and meta-analysis was performed to evaluate the complications, safety, and outcomes of intramuscular fat grafting.

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered with the International Prospective Register of Systematic Reviews. A comprehensive literature search was performed across multiple databases, including Embase/Elsevier, Cochrane, Scopus, PubMed/MEDLINE, BVS, SciELO, and Lilacs. This search covered all years and languages. The included studies were assessed for risk of bias using the Risk of Bias in Nonrandomized Studies of Interventions tool to ensure methodologic rigor. A total of 36 studies were selected for qualitative synthesis.

The meta-analysis included 27 studies with 208,692 observations and 857 events. Among those specifying the target muscle, 25% injected the gluteus, 8.3% targeted the rectus abdominis, and 5.6% targeted the gastrocnemius and soleus. The pooled complication rate was 6.2% (95% CI, 3.06% to 12.13%), with substantial heterogeneity among the studies ( I² = 98.3%). The most common complications included fat embolism, infection, seroma, hematoma, fat necrosis, asymmetry, and revision surgery. Fat embolism was the most serious complication, with a mortality rate of 1:3000 cases of gluteal intramuscular fat grafting.

Intramuscular fat grafting offers aesthetic benefits but poses risks, including fat embolism. Advancements such as ultrasound guidance enhance safety, but further research is needed to refine techniques and establish evidence-based guidelines.