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Perpendicular ‘strut’ HA injections provide superior, lasting results for deep nasolabial folds

Fifteen to 30 injections per fold allow peak improvement to last longer, though overall duration of improvement is unchanged

A technique involving constructing ‘struts’ of hyaluronic acid (HA) dermal filler through multiple injections perpendicular to deep facial creases appears to produce improvements in the appearance of nasolabial folds that remain more consistent through to six months.

“It is not easy to treat deep wrinkles by intradermal injection of HA. We wanted to maximize short- and long-term outcomes of [HA injections in these wrinkles],” said the study’s lead author, Dr. Kotaro Yoshimura, professor and chair of the Department of Plastic Surgery at Jichi Medical University in Tochigi, Japan, in an email interview with

Dr. Kotaro Yoshimura

In the paper, published in Plastic and Reconstructive Surgery Global Open (Dec. 9, 2015; 3(11):e567), Dr. Yoshimura and his colleagues note that while the intradermal injection is a basic approach to treating deep wrinkles, unfavourable results sometimes arise including conspicuous ridging or beading on or adjacent to the target wrinkle. As well, sometimes the injection has a negligible effect on wrinkles and creases. The investigators tested a technique of injecting multiple perpendicular ‘struts’ of HA to see if that technique might provide more consistent intradermal structural support.

Dr Kotaro Yoshimura

Split-face comparison

The trial enrolled 10 consecutive individuals—one man and nine women—with ages ranging from 39 to 67 years (mean age 50.2 years). Each participant had bilateral nasolabial fold ratings of two (mild) to four (severe) on the five-grade Wrinkle Severity Rating Scale and had not received any facial rejuvenation treatments in the preceding six months.

With the skin stretched fully taut, patients were injected 15 to 30 times across the nasolabial fold area on one side of their face. Injections were made approximately 1mm apart, with the needle almost parallel to the skin surface. The full length of the needle was inserted (0.5 in), and then HA was introduced as the needle was extracted, creating a 10 to 12 mm strut perpendicular to the nasolabial fold. Each strut consisted of 0.01 to 0.03 mL of HA filler.

The opposite side of each patient’s face was treated with HA filler using a conventional linear threading and fanning techniques.

Three blinded, certified plastic surgeons graded the Wrinkle Severity Rating Scale of the nasolabial fold area before treatment, and at four and 24 weeks after treatment using clinical photographs. The evaluators also answered the question ‘which side had better improvement, judging from a comparison of before and after photographs.’

Significant improvement at four weeks vs. conventional techniques

The researchers reported that all 10 patients completed the study. Four weeks after treatment there was a significantly larger improvement in Wrinkle Severity Rating Scale grade in the areas treated using the strut method (1.7) than in the conventional side method (1.3; p=0.036). Improvements from baseline had largely disappeared by 24 weeks after treatment regardless of treatment type. A significant difference in improvement was also reported between the two sides, favouring the strut technique, at week 4 (p<0.01), but the difference became non-significant by week 24 (p>0.05), the authors wrote.

Temporary adverse events including erythema, bruising, swelling, induration, pain, and numbness were reported, but all disappeared within two weeks and no other serious complications occurred.

“This can be a fundamental technique of intradermal injection,” said Dr. Yoshimura. “It is very simple and easy.” Using this strut technique can produce better, lasting results than linear threading and fanning techniques in deep folds, he said.

However until the technique is mastered, Dr. Yoshimura recommends having a skilled assistant to maintain the skin in the taut state. “This is important to get good results consistently using this technique.”

Multiple HA injections perpendicular to a crease to create structure have been used before, said Dr. Vince Bertucci, but Dr. Yoshimura and his team are injecting more deeply than with the fern injection pattern. Dr. Bertucci—co-director of the Dermatologic Laser Surgery and Cosmetic Dermatology Fellowship at the University of Toronto–lauded the authors for their side-by-side comparison of the perpendicular strut technique to linear threading and fanning techniques. He commented that it would have been nice to see clinical evaluations between 4 and 24 weeks to help discern the duration of advantage enjoyed by the authors’ technique.

Dr. Vince Bertucci

“The concept is that if you can create stiffness across a fold, then when we make an expression such as a smile you will be able to minimize the visibility of that wrinkle because it will not be able to crease as much, given the fact that it is stiffer,” said Dr. Bertucci.

Potential for longer downtime

There are a couple of downsides to the technique, said Dr. Bertucci. “It requires multiple needle injections or needle sticks. When you are using multiple needle sticks there is a higher likelihood that patients are going to swell more. And potentially there is a higher incidence of bruising.”

While the rate of bruising was not significantly higher in the 10 patients in the study by Dr. Mashiko and colleagues, Dr. Bertucci said in his clinical experience more needle sticks generally result in higher bruising rates. “So downtime might be longer than with cannulas or techniques that utilize less needle sticks, but this parallel strut technique is a good treatment option.”

Ultimately this technique represents another tool in a cosmetic practitioner’s toolbox, said Dr. Bertucci. “For patients with more etching or deeper lines, who can tolerate the potential for more downtime after their treatment, this technique would be a good choice,” he concluded.

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