Fillers can be administered in multiple ways, and the question of when and where to use cannulas vs needles is actually a complicated one in my practice, as I do not have a one size fits all approach.
Fillers at Nuance Facial Plastics are done with cannulas when possible. There are multiple ways to have fillers done, and the most important thing is getting the best results. The next highest priorities are to minimize pain, bruising, and swelling. This is why I have switched from using needles in the past to almost exclusively using cannulas. I have found them to be better tolerated and able to deliver the same, if not better results.
Most of us are familiar with needles. They are sharp, and readily pierce through skin and anything else that gets in their way with surgical accuracy. They are very efficient at delivering drugs, vaccines, and fillers as well. The reason is that they are essentially scalpels with a hole in the middle. They have different sizes, and they also have different shapes, coming to a point either slowly (long bevel length) or quickly (short bevel length).
Does this matter? When precision is of utmost importance, it does matter. Generally, the larger the needle, the longer the bevel length. This usually is not a problem, though it can be in areas that are thin or delicate. One example I give below is the tear troughs.
A micro-cannula is a hollow bore injection device similar to a needle, but instead of coming to a sharp point, it has a bullet-shaped end with an injection hole on the side. Usually longer than needles, cannulas also come in different sizes and shapes. They have a marked advantage over needles because when they are pushed through tissues, they respect natural tissue boundaries. When they are inserted into the subcutaneous fat layer, they will continue in this plane unless forced out of it. They also have a tendency to not cut blood vessels and nerves, as the blunt tip moves around these important structures with less injury. This reduces bruising and swelling after treatment.
The tear troughs are a bone (the inferior orbital rim) covered by a paper-thin layer called periosteum, and then a thin layer of muscle followed by the thinnest skin of the body. Tear trough fillers are ideally placed between the periosteum and muscle. The main point here is that the soft tissue overlying the tear trough is thin. This is an issue when injecting them with needles, as the tip of the needle only goes as far as the bone, and the level of the needle may force the filler to get placed more superficially than the “ideal” layer, giving it a lumpy appearance. Also, this area, in my experience, is the most likely to bruise when injected with needles due to their lack of respect of tissues. They plunge through everything, cutting blood vessels without pause.
About two years ago, I switched to a cannula technique to treat tear troughs. What a difference! An area that used to have much swelling and bruising (I would quote people a 20-30% chance of bruising) no longer does. Tear troughs are a very common area that I treat, and since switching to cannulas, only one of my patients has had bruising (sorry!). I didn’t calculate the rate, but it is in the “very low” category. Short term swelling, which usually resolves in 3-4 days after the treatment, is also much less than it used to be when I used needles. Furthermore, the treatments are faster and with less pain and discomfort, being a “win” for all.
The outer 1/3rd of the lower eye circles are a hard area to fill with a cannula. If you feel this area, you will notice a notch in the bone. This is the insertion site of muscles and is quite dense with tendons. Here, a cannula would pass through tissues easily if we are filling an area in a natural tissue plane. I find this area particularly hard to treat with a cannula because there are many dense tendons meeting and inserting into bone, so the cannula not only requires a lot of force to maneuver, but I cannot place it exactly where I want to. Luckily, this area has a fairly easy solution.
I use a soft filler in this area and transfer the filler to an insulin syringe prior to filling. This is a needle technique, and to overcome the shortcomings of the needle technique here, the long bevel of the needle, I use the smallest needle I have available that I can pass fillers through. It is a 0.3cc syringe with a 31 Gauge needle, which has the shortest bevel and smallest diameter, making it easy to pass through the tissues and place with sub-millimeter precision.
Treating lip lines, or “smoker’s lines”, can be tricky, and softening of the valleys of these lines in my practice involves placing a small amount of filler to make the sharp valley into a less deep, less sharp valley. This sub-millimeter precision, and placement within the dermis of the skin make a cannula technique less precise. As the needle passes within the dermis, which is a tough layer of the skin that gives it support, it “cuts” a hole in which to place filler. This does not work well with a cannula, as it lacks the sharp tip, instead preferring to pass deeper in the thin fatty layer under the skin. This is just the wrong location to place filler to treat these lines and would require using a lot more material and give a worse result.
Getting a filler treatment is not about how it is injected. Treatments are about results. At Nuance Facial Plastics, the best tool for any given goal is used, whether it is a needle or a cannula. The benefits of using a cannula over a needle or vice versa are primarily about the results, though nobody ever complains about having less bruising, swelling, and discomfort from using a cannula when appropriate.