Long-Term Follow-Up of the Behavior of Facial Volumizing Cross-Linked Hyaluronic Acid Gels

Abstract

Introduction: We present the long-term follow-up photographic and MRI data on 4 patients 42-44 months after cross-linked Hyaluronic Acid (HA) gel injection into the temple region. All injected HA gels were produced using the registered and patented “Inter Penetration Network Like®” (IPN-Like® cross-linking technology) (LABORATOIRES VIVACY, France). The initial results following injection and up to 24 months were previously reported [1,2]. Material and methods: Our study population comprised 4 Caucasian patients who were enrolled into our two previous studies that compared Stylage XL versus Stylage XL-Lido (incorporating lidocaine added at manufacturing) [1] and Stylage XL versus Stylage XXL [2]. Patients, radiologists and the independent evaluators were blinded to the type of product used. The 4 patients were each injected in both temporal fossae using the 2 different HA gels being compared (one on either side). All patients had their follow-up at month 42 after injection (M42) with the exception of one patent who her MRI and photographs taken at the same setting on month 44 (M44). Photographic assessments were undertaken by the injector and 2 independent experts using Merz-Analogic Scale® (MAS®) and the Global Aesthetic Improvement Scale (GAIS). Results: Except for participant 2 (Stylage® XL vs. Stylage® XL-Lido) on the Stylage® XL-Lido side, all the other participants were considered to have a degree of persisting improvement compared to baseline, according to experts scoring of photographs on MAS and GAIS, However, there was a gradual deterioration in the level of improvement compared to the other assessment time-points. MRI: Although the bolus of injected gel was spherical at D0, we observed a change in the shape of the implant over time on MRI, where it changed from a round to a “teardrop” shape. Slow resorption occurred from 18 months onwards. At M42-44, the gel appearance on MRI remained similar to that previously reported at M18. The MRI residual volume calculation showed persistent increased volume compared to the volume initially injected. The product location appeared stable. There were no radiological or clinical signs of inflammatory reaction in tissues adjacent to the gel. Conclusion: At long-term follow-up 42-44 months after initial injection there was still an improvement in the aesthetic appearance of the temporal fossa and the MRI images show the continued presence of the gel. We also noticed that Stylage®XL (without lidocaine) seemed to absorb more water than its counterpart with lidocaine. Likewise, Stylage® XL seemed to absorb more water than Stylage® XXL.