Importance: Soft-tissue augmentation with skin fillers can be delivered with needles or microcannulas, but unwanted vascular occlusions are possible. Objective: To determine whether filler-associated vascular occlusion events of the face occur more often with injections performed with needles than with microcannulas. Design, Setting, and Participants: This retrospective cohort study included a random sample of board-certified dermatologists deemed eligible based on membership in relevant professional societies and attendance at relevant national professional meetings. Participants completed detailed forms in which they could enter deidentified data and volume statistics pertaining to patients undergoing filler procedures in their practices. Data were collected from August 2018 to August 2019. Exposures: Injectable fillers approved by the US Food and Drug Administration delivered via needles or microcannulas. Main Outcomes and Measures: The primary outcome measure was intravascular occlusion. Occlusion events were graded by severity (no sequelae, scar, and ocular injury or blindness). Results: A total of 370 dermatologists (mean [SD] years in practice, 22.3 [11.1] years) participated and reported 1.7 million syringes injected. The risk of occlusion with any particular filler type using needle or cannula never exceeded 1 per 5000 syringes injected. Overall, 1 occlusion per 6410 per 1-mL syringe injections was observed with needles and 1 per 40882 with cannulas (P <.001). Of the 370 participants, 106 (28.6%) reported at least 1 occlusion. Multivariate analysis found that injections with cannula had 77.1% lower odds of occlusion compared with needle injections. Participants injecting fillers for more than 5 years had 70.7% lower odds of occlusion than those who were less experienced. For each additional injection per week, the odds of occlusion decreased by 1%, and 85% of occlusions had no long-term sequelae. Nasolabial folds and lips were most likely to be occluded, with mean severity level of occlusions highest at the glabella. Conclusions and Relevance: In this cohort study, filler injections with either needles or cannulas were associated with a very low risk of intravascular occlusion events. Moreover, the vast majority of such events were minor and resolved without scar or other injury. Injections with microcannulas were less often associated with occlusion events than injections with needles. Occlusion risk per syringe appeared decreased after the first few years of clinical practice and was also lower among those who more frequently inject fillers. Whether a needle or cannula is most appropriate for injection may depend on patient factors, anatomic site, and the type of defect being treated.
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