Precision in Dermal Filling: A Comparison Between Needle and Cannula When Using Soft Tissue Fillers
September 2017 | Volume 16 | Issue 9 | Original Article | 866 | Copyright © September 2017
Tatjana Pavicic MD,a Konstantin Frank,b Katharina Erlbacher PhD,c Romy Neuner,b Stefan Targosinski MD,d Thilo Schenck MD PhD,b Robert H. Gotkin MD FACS,e and Sebastian Cotofana MD PhDf
aPrivate Practice, Munich, Germany bDepartment for Hand, Plastic and Aesthetic Surgery, Ludwig Maximilian University, Munich, Germany cDepartment of Cell Biology & Physiology, University of Salzburg, Austria dDivision of Thoracic Surgery, University Hospital Zurich, Zurich, Switzerland ePrivate Practice, New York, NY fDepartment of Medical Education, Albany Medical College, Albany, NY
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.
J Drugs Dermatol. 2017;16(9):866-872.
As of the end of 2016, 24 different soft tissue fillers have been approved by the Food and Drug Administration (FDA) since 1981; these fillers may be used to reduce the signs of aging on the face and other parts of the body.1 The growing popularity of this minimally invasive therapeutic approach has led to an increase in the use of soft tissue fillers by 298% between the years 2000 and 2016.2 Their use provides a non-surgical opportunity to augment, correct, and modify the soft tissue and skin envelope while, at the same time, being highly predictable and having reduced down-time compared to most surgical procedures.3,4 Albeit easy to inject, these fillers have a plethora of adverse effects ranging from ecchymosis, edema, erythema, infection, herpetic outbreak, nodules, and granuloma formation to more severe complications such as vascular compromise that may result in tissue necrosis, hemiplegia, aphasia, and blindness.5-9 The latter has been hypothesized to result from intravascular injection of the volumizing material and the ultimate obstruction of the retinal vessels.10-13 In order to minimize the risk of intravascular injections, blunt tipped cannulas have been introduced for the application of volumizing agents; they are designed to atraumatically slide within the tissue planes and spare the neurovascular structures.14-16 A recent study by van Loghem, et al17 reported that 71% of 58 expert injectors considered a cannula to be safer than a needle for injecting fillers into the supra-periosteal plane, but 79%, however, considered a cannula to be less precise when compared to a needle. With increasing anatomical knowledge about the facial fat compartments,18,19 the precision placement of the implanted soft tissue fillers is of great importance for patient safety and best possible aesthetic outcomes. Several studies17,20 compared the outcome of injections performed with needles vs cannulas and reported that filler injected with needles tended to migrate towards more superficial layers and that needles seem to be less precise in a vertical (deep-super cial) orientation. However,