INTRODUCTION
Soft tissue fillers are commonly used to help restore age-related volume losses in the face and hands.
In the United States, fillers are currently administered with the use of sharp needles. The procedure is generally considered safe, however, adverse events do occur. These
range from common bruises to rare reports of serious complications such as skin necrosis, blindness, or stroke.1
Cannulas are tubes that can be used to administer products or fluids into the body. Unlike hypodermic
needles, which have sharp, beveled tips, cannulas typically have blunt ends (Figure 1). Cosmetically, cannulas have been used for years in the United States for fat transfer
procedures. The large size of these cannulas best suited them for subcutaneous injections, as intradermal injections require a more precise placement method.2
Recently, smaller cannulas have become available in the United States that can be used to administer
intradermal tissue fillers. These types of cannulas have become commonplace in Europe and other regions of the world over the past few years as well. They provide the safety
benefit of a blunt tip and a flexible body, while allowing for administration of almost all filling agents.3
DISCUSSION
Soft tissue fillers are currently administered through hypodermic needles with sharp, beveled tips. These
needles allow for precise deposition of product within the dermis or subcutaneous tissue. The gauge and length of the needle used depends on the properties of the filling
agent itself, the preference of the injector, and region being treated. Less viscous fillers are commonly administered through a 30-gauge needle. Though currently formulated
filler products in the United States come prepackaged with the recommended needle, many injectors have other preferences. Off-label, these injectors may employ a 32-gauge
needle as well-especially to tuck into finer etched-in lines such as in the perioral area. More viscous fillers require larger needles, ranging from 27-gauge (e.g., large
particle hyaluronic acid or calcium hydroxylapatite) to 25 or 26-gauge (e.g., poly-L-lactic acid).4 Needle length depends on the injection technique and the anatomic location
being treated. Needles ranging from ½ inch to 1¼ inches long are commonly used.
The most common adverse event patients experience from soft tissue augmentation is the development of a
bruise. Bruising develops when blood extravasates from blood vessels as a result of soft tissue trauma. Certain injection techniques have been identified as having a higher
risk for bruising, and even the most seasoned injector may sometimes give patients a bruise. A fan-like injection technique, rapid injection, rapid flow rates, and higher
product volumes (often associated with more needlesticks) in a given area are all associated with a higher risk for bruising.5
Serious complications from administration are rare but do occur. These include vascular occlusion or
embolization with
