Would hyaluronic acid-induced mental bone resorption be a concern? A prospective controlled cohort study and an updated retrospective cohort study

Background: Hyaluronic acid is a widely used filler for face contouring and is generally believed to be safe and effective. However, there have been reports of hyaluronic acid related bone erosion in the chin area without clear scientific data regarding its existence, incidence and severity. This exploratory study was to evaluate HA-related mental bone resorption through a prospective, controlled, observer-blind, non-randomized clinical trial and a retrospective cohort study. Methods: On one hand, a prospective, controlled, non-randomized, single-shot HA injection clinical trial was conducted. Computed tomographic (CT) scans were collected at baseline and at 6~12 months of follow-up for both HA-injection and control groups. On the other hand, an updated retrospective cohort study compared the HA-injection with a blank control group. The primary outcomes composed of three quantitative parameters [bone resorption index (BRI M and BRI N ), bone resorption thickness ratio] and one subjective evaluation index (severity ranking). Information about demographics, complications, injection volume were also recorded. Results: From June 2021 to March 2023, 78 patients were prospectively recruited for the study. There was a significant association between HA injection and bone resorption [BRI M : pre (84.24%±8.10%) vs post (79.21%±8.70%), P＜0.001 ; BRI N : pre 92.50% (73%, 144%) vs 87.99% (63%, 132%) , P＜0.001 ; Bone thickness ratio: HA 24.08% (0, 48%) vs Control 0 (0, 17%), P＜0.001 ]. However, there was no difference in large-volume(>1ml) and small-volume(≦1ml) injection subgroups[bone resorption thickness ratio: (21.50%±10.91%) vs (24.51%±11.92%), P=0.350 ]. The imaging manifestation revealed discernible bone resorption in 35.90% of the patients, with an median bone resorption thickness ratio of 24.08%. Between October of 2019 and March 2023, 95 HA-injection patients (190 semimandibular cases), 95 normal controls were enrolled. The BRI M was significantly lower in the HA-injection group compared to the controls ( P＜0.001 ). Conclusions: Hyaluronic acid may induce bone resorption in the mentum. Large-scale randomized controlled clinical trial is warranted for further confirmation. Patients should be informed of this potential complication.