Background: Predicting the degree of fat graft retention is essential whenplanning reconstruction or augmentation with free fat grafting. Most surgeonsobserve volume loss over time after fat grafting; however, the portion lost toresorption after surgery is still poorly defined, and the time to reach steadystate is unknown.
Methods: The authors compiled a retrospective, longitudinal cohort of patientswith vestibular schwannoma who had undergone ablative surgery and reconstructionwith excised fat between the years 2006 and 2015. Fat volume retentionwas quantified by computed tomography and magnetic resonance imagingand used to model a graft retention trajectory and determine the volumetricsteady state. In addition, the authors evaluated the association between graftretention and secondary characteristics, such as sex and transplant volume.
Results: A total of 108 patients were included. The average baseline graft volumewas 18.1 ± 4.8 ml. The average time to reach steady state was 806 days aftertransplantation. By this time, the average fat graft retention was 50.6 percent(95 percent CI, 46.4 to 54.7 percent). No statistically significant association wasfound between baseline graft volume and retention. Fat graft retention overtime was significantly higher in men than in women (57.7 percent versus 44.5percent; p < 0.001).
Conclusions: The authors’ data provide evidence that the time to reach fatgraft volumetric steady state is considerably longer than previously expected.Fat grafts continue to shrink long after the initial hypoxia-induced tissue necrosis has been cleared, thus indicating that factors other than blood supply may be more influential for fat graft retention.