RESUMEN
BACKGROUND: Uncontrolled product spread is an important issue to consider in facial filler injections. Lack of precision can result in reduced effectiveness and surface projection, as well as irregularities and product visibility. OBJECTIVES: The authors sought to assess the precision of soft-tissue filler injections in the face by employing a cannula. METHODS: This single-center observational study investigated soft-tissue filler distribution utilizing real-time non-invasive ultrasound imaging. Outcome parameters included (1) the tissue plane of product distribution, (2) the extent of horizontal as well as vertical product spread at the injection site, and (3) the product surface area taking into account the multifactorial influence of several independent variables. Participants were followed up to 30 days post-injection. RESULTS: A total 100 facial injections were performed in 8 patients (2 males, 6 females) with a mean age of 37.20 (±6.34) years and a mean BMI of 22.21 (±1.39) kg/m.2. The plane of product distribution remained constant in approximately 90% of cases at day 0 (d0), d14, and d30. Mean horizontal product spread was higher compared with vertical spread, and both significantly decreased over all time points (P < .001). Mean product surface area was 22.51 ± 16.34 mm2 at d0, 15.97 ± 11.28 mm2 at d14, and 12.9 ± 9.15 mm2 at d30. Analysis employing generalized linear models revealed that injection volume and injection depth significantly influenced product surface area. CONCLUSIONS: Injection of soft-tissue filler employing a cannula allows precise application of the product within the intended tissue plane. Precision can be improved by injecting less product into deeper tissue layers.