Precise Needle and Cannula Placement in the Forehead During Aesthetic Procedures: Can Device and Angulation Influence Accuracy? A Fresh Frozen Specimen Study.

ABSTRACT

INTRODUCTION: Myomodulation is a technique aimed at enhancing the dynamics of muscle contraction and relaxation through methods like hyaluronic acid (HA) injection. Achieving optimal outcomes depends on the precise placement of the injected product within the targeted anatomical plane. This is particularly important in the forehead, an area with elevated vascular risk. The selected treatment techniques must ensure both efficacy and safety. This study aims to assess the anatomical precision of HA injections in the forehead using different techniques and devices. METHODS: Four fresh frozen specimens were injected with HA by five experienced board-certified plastic surgeons using three different techniques/devices (1) a 50 mm, 22G microcannula; (2) a 13 mm, 27G needle with the bevel down at a 45-degree angle; and (3) the same needle positioned at a 90-degree angle. Ultrasound analysis was used to evaluate the precision of each approach. RESULTS: Both the cannula technique and the needle technique with the bevel down at a 45-degree angle consistently delivered the filler to the supraperiosteal layer in 100% of cases without spreading. However, the 90-degree needle technique, despite correct placement on the periosteum, resulted in filler dispersion across multiple layers. CONCLUSION: The accuracy of filler placement in the forehead is influenced by the choice of device and its angulation. It is recommended to use a cannula with the entry point at the frontalis crest or a needle angled at 45 degrees to the skin. The use of a needle at a 90-degree angle should be avoided to ensure precise placement and avoid filler migration. NO LEVEL ASSIGNED This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00266 .