Anatomical layer analysis for safe thread insertion using micro-CT and ultrasonography: enhancing precision in facial thread-lifting procedures

Background: Thread lifting is considered a relatively noninvasive and effective treatment for facial rejuvenation compared to traditional facelift surgery. However, no consensus exists on anatomically favorable insertion layer for threads into the lateral facial area. This study aimed to examine the anatomy of the lateral face, particularly the superficial musculoaponeurotic system, and facial nerve course, and evaluate the safety of thread insertion into this region. Materials and methods: Eight fresh cadavers were used. Thread insertion was performed in the lateral face with a single entry point at the temple area. Three threads were inserted: one terminated 1 cm lateral to the mouth corner, and the other terminated 1 cm lateral to the first termination point on either side. The safety of thread insertion was assessed using two advanced imaging modalities-micro-computed tomography with the contrast-enhanced agent phosphotungstic acid and ultrasonography. Results: The threads were successfully inserted into the correct layer, superficial to the superficial musculoaponeurotic system, without damaging critical anatomical structures such as vessels, nerves, or muscles in the lateral face area. Conclusion: This study demonstrated that thread insertion into the superficial layer of the superficial musculoaponeurotic system is anatomically favorable approach for lifting lateral facial tissues. This layer offers the potential for achieving feasible results while minimizing iatrogenic complications in thread-lifting procedures.