Precision in Dermal Filling: A Comparison Between Needle and Cannula When Using Soft Tissue Fillers.

BACKGROUND: Precise implantation of soft tissue fillers to treat the signs of aging is crucial for patient safety and the best aesthetic outcome. Injections are performed commonly with either needles or cannulas, but quantitative comparative data on precise implantation are still elusive.
METHODS: Ten fresh-frozen cephalic foreheads (9 male, 1 female) were injected with radiopaque material using both needles and cannulas. Needle injection relied on a perpendicular transcutaneous approach, whereas cannulas were moved in the supra-periosteal plane until reaching the same location as the needle. Two-dimensional distribution of the material in the horizontal and in the vertical axes was quantified using fluoroscopic imaging. Additional CT and MR imaging was performed to confirm results.
RESULTS: The two-dimensional extent of injected material in the horizontal plane was 25.6 mm±10.5 mm vs 13.5 mm ± 6.5 mm (cannula vs needle; P=0.006) and 3.0 mm ± 0.90 mm vs 3.99 mm ± 0.97 mm (cannula vs needle; P=0.028) in the vertical plane. In 60% of injections using a needle, the implanted material changed its plane; this was not observed when using the cannula (0%; P=0.003). Retrograde backflow, however, was greater with a cannula (90.2%) compared to a needle (33.3%).
CONCLUSIONS: If precision in filler injection is defined as the filler material remaining in the plane of intended implantation, then using cannulas resulted in a more precise injection of material as compared to needles. Applications with needles resulted in the distribution of material into more superficial layers, which was not noted for cannulas. <p><em>J Drugs Dermatol. 2017;16(9):866-872.</em></p>.