Use of dermal fillers to achieve volumising and also hydration of the ageing face has grown exponentially over the last ten years or so. The type, size and application of the dermal filler has also changed and we now enjoy unparalled choice in terms of which dermal filler to use in which part of the face, neck and décolletage.
Hyaluronic acids remain the most popular US and EU regulatory approved fillers and Restylane and Juvederm enjoy big brand presence in the market place. Both brands have hyaluronic acid preparations with or without local anaesthetic and of different consistency to treat different areas of the face.
The one thing they all have in common though is that they come pre-packed with a sharp hypodermic needle of varying diameter. QMed recently held an advanced practitioner workshop in Paris to train on the use of a novel technique employing a fine, blunt ended cannula with aperture above and lateral to the cannula tip.
What's wrong with needles?
Needles have several adverse characteristics. They are necessarily sharp and during introduction into the area to be treated they will:
lacerate blood vessels
require repeated insertion to re-position
cause collateral tissue damage
cause associated bruising
for a small minority they may terrify the patient.
Cannulas have a mixed provenance though. In 2004 my business partner Dr Sean Cummings was trained as a Restylane Sub Q Trainer in Uppsala and returned from that event with a small suitcase of SubQ and a large supply of 18 gauge 3 inch long cannulas. The idea at the time was to make a stab incision with a size 11 blade at the desired point of origin and then insert the colossal cannula into the target area. The big blunt end required considerable force to push it through the tissues and the large lateral aperture through which the filler was expelled snagged as it was moved about in the tissue. Needless to say, it wasn’t a winner and my colleague swiftly reverted to needles instead.
Now, the size 18 gauge has shrunk to as little as a 21 to 23 gauge cannula for SubQ and 25 to 30 gauge for others and is the perfect device for a-traumatic, near painless, bruise free insertion of even large gel particles.
In my own practice I have almost abandoned the use of sharp hypodermics and have substituted insertion of these tiny, flexible and every so smooth cannulas instead. The ultimate test was when I wheeled my cynical colleague Dr Cummings into my treatment room and filled both tear troughs with no anaesthetic and no pain. One day later, complete resolution of the defect area and no bruising was the result.
When are cannulas better than needles?
Cannulas are ideal where bruising a likely result of filler injection. Good examples are the lip and also the tear trough and also deeper into the naso-labial grooves. Treatment of the décolletage is possible and encouraged although it does require some hand holding in terms of cannula-naïve injectors.
Treatment of the lip, as illustrated in the before and after photos above, results in a smooth, bruise free fill. The technique involves screwing the cannula to the syring instead of the supplied needle. Product is expressed along the cannula prior to injection for two reasons. Firstly and obviously to express any contained air. Secondly, again for the injector new to cannula use, the filler will be expressed much more rapidly and in a much more uniform way than with conventional needle and it is best to experience this outside the patient than within.
The cannula is inserted via a small access port created by puncturing the insertion point with a needle of slightly greater diameter than the cannula itself. The cannula is inserted right the way along the lip and on withdrawal the product is injected. This gives a smooth gentle fill. A small amount of massage may be required. Care should be taken to avoid pushing the newly placed product out of the 18 or 16 g puncture site.
Similarly, when treating the tear trough area, a single puncture using an 18 g needle is made inferolateral to the treatment target. The blunt ended cannula is then inserted and a classic tear trough fill is performed with angulation of the cannula down to the bone, advancement of the cannula under direct vision and also palpation using the non-dominant index finger to the desired point. Once again, the cannula is withdrawn whilst gently expressing the dermal filler. Extra care is required in this area to avoid the hazard of creating a Tyndall effect. The tear trough is a particularly challenging area in any event with numerous fine blood vessels ready for damage so the advent of a non-traumatic technique is overdue.
What are the benefits of flexible fine cannulas?
It can be seen that there are several distinct advantages to using the new, flexible fine cannulas for injecting dermal fillers:
with no bruising, patients may really return to work or social functions immediately afterwards
the term 'lunch-time' treatment is entirely appropriate
patients who may be needle phobic are reassured when they see the cannula and further reassured by the genuine lack of pain.
For the practitioner, an enthusiastic, relaxed patient is a bonus and the technique allows for precise delivery of ideal amounts of dermal filler. The procedure takes slightly longer, reduces bruising, bleeding and swelling and enables the practitioner to create a lifted face. Training is needed to be confident and to hone injecting skills.