Ultrasound characteristics of hyaluronic acid fillers tissue integration and hyaluronidase-mediated degradation

Background. Currently, the study of the efficacy and safety of hyaluronic acid (HA) fillers is not limited to clinical observations. Modern non-invasive techniques, in particular, ultrasound (US) imaging of soft tissues allows detailed assessment of the results of aesthetic treatment. Objective. To describe the processes of HA fillers tissue integration and hyaluronidase-mediated degradation. Material and methods. The study involved 8 patients who underwent aesthetic facial treatment with HA-based fillers produced by technology MCO. Tissue integration and degradation by hyaluronidase were assessed based on US examination. Results. After injection of HA fillers, US scan showed a globular pattern with anechoic zones indicating fluid content. There were no signs of vascularization or infiltration of surrounding tissues. The absence of signs of swelling and fibrosis and the appearance of hypoechoic inclusions along the periphery of the filler indicate a physiological process of integration of the filler into the surrounding tissues. Initial signs of tissue integration of the filler were observed 3—4 weeks after injection. The doses of hyaluronidase (bovhyaluronidase azoximer) that can be used to degrade 0.1 ml of HA filler ranged from 100 to 300 IU depending on the rheological properties of the gel. The dose of hyaluronidase can be increased 3 times in the case of vascular occlusion. Conclusion. Tissue integration of the studied fillers occurs in the early stages without signs of an inflammatory response including edema, infiltration, proliferation of local vascular networks. HA fillers produced by MCO technology are rapidly degrades by exogenous hyaluronidase.