A roadmap for safety during facial filler injections: A fresh frozen cadaver study.

[BACKGROUND] Filler injections are commonly applied to reshape facial contouring. However, cadaveric injections of filler for facial contouring on the whole face, followed by anatomic analysis and measurement, have rarely been reported. This study aimed to provide comprehensive anatomical information, including topographies and roadmap of injection point entry, penetration depth, filler location, the hierarchy of facial structure, and vital vascular course.

[METHODS] Thirty faces on fresh frozen cadaver heads were used for this anatomic study. The whole face was divided into seven facial zones and 14 injection points for penetration depth measurement and cadaveric injection. Static periosteum injections with a sharp-needle technique were performed. Specimens were then dissected to observe the precise locations of fillers and their relationships with surrounding anatomic structures.

[RESULTS] The topography of penetration depth gradually increased from the upper face to the middle face, lower face, and temporal region. Most of the injected hyaluronic acid filler flowed backward to the loose areolar tissue layer between the superficial musculoaponeurotic system and periosteum or deep fascia. Multilevel layer distributions and anastomosis of the vessels were found in the face, especially in the glabella, dorsum nasi, and temporal regions.

[CONCLUSIONS] This study can provide clinicians with a comprehensive reference for facial contouring injections: topographies of the injection point and penetration depth and the vascular anatomical structure in high-risk facial zones. The static periosteum injection with effective aspiration is recommended as a relatively safe technique. Clinicians are supposed to grasp the anatomy and injection technique to achieve maximum safety during filler injections.