Injectable HA: More than fillers

Hyaluronic acid products can treat a range of indications, including improving acne scars

Just as a chef will use an array of different knives and utensils in the course of preparing a meal, no single hyaluronic acid (HA) product  is going to be ideal for every aesthetic dermatology application, according to Dr. Andrei Metelitsa during a presentation at Dermatology Update in Toronto in April.

"When we think about our faces and the areas that we are treating, whether it is the tear trough region, the lip, the nasolabial fold ... it comes as no surprise that we require different types of injectable fillers to enhance our treatment protocols," he said.

Dr. Metelitsa is co-director of the Institute for Skin Advancement in Calgary, and a clinical associate professor at the department of medicine at the University of Calgary.

Properties vary between products
HA filler products from different manufacturers have different physical properties, Dr. Metelitsa said. In many cases practitioners would need to familiarize them­ selves with offerings from multiple suppliers or limit themselves to performing procedures that could be effectively performed using products they were comfortable with.

"In the past, many of us would jump between various products from different companies, because we needed to utilize both soft gels and firm gels," he said. However, manufacturers such as Galderma are now producing multiple lines of HA fillers-varying one or two factors, such as the G' modulus, the degree and method of cross-linking, or the grain size, while consistently maintaining the other properties - which may allow practitioners to be more confident in achieving consistent outcomes.

Firm vs. thinner fillers
Firmer gel products are better for lifting and for precision applications, Dr. Metelitsa said. They are "great for areas such as the jawline, the folds, and the cheeks in certain individuals," he said, describing successful cases of using these products in the tear trough areas and to improve chin projection.

"I use them for people who have a thicker skin texture-so maybe a younger patient who has a little bit firmer skin."

This firm gel category includes the Restylane NASHA (non-animal stabilized hyaluronic acid) products.

The firmness of these products means that clinicians need to reconsider their use in areas of the face that animate, though, he said.

"Why do we care? Because our patients express themselves," said Dr. Metelitsa. Too firm a gel in a mobile part of the face might look acceptable in a neutral expression but could look unnatural during a smile. "So the desired histology here looks a bit different."

"This is a huge topic in cosmetic medicine because for the longest time, everyone used to take before and after pictures [that looked great], but when the patient smiled or made some other expression all you see is this filler projection," he said.

HA fillers with smaller particle sizes, and consequently less firm gels, are "great for contouring and natural expression," he said. They distribute through and integrate into the tissue better.

Dr. Metelitsa said that he often uses Restylane Optimum Balance Technology HA products in these applications, which have the same HA concentration as the NASHA products - 20 mg/mL - but with more variability in the degree of cross­ linking and the particle size.

Improving skin quality with HA
Revolumizing and contouring are not the only applications of HA in facial rejuvenation, however. The injection of cross-linking­ stabilized HA into the skin has an additional benefit of increasing the natural levels of HA, said Toronto dermatologist Dr. Lisa Kellett, in a presentation at Dermatology Update.

This is important because it supports the radiance of skin, she said. "When patients come to us, they will not say: 'I need volume.' They will say: 'I want my skin to look better."'

"Their skin is dull and they want more radiance," Dr. Kellett said. "We know that 67 per cent of women considering treatments stated that looking refreshed and improving their skin's appearance was one of their most important treatment goals. Two-thirds of women surveyed wanted to refresh their skin's appearance with some sort of facial injectable treatment."

Yet there are places where adding volume is not desirable--such as the thin skin of the neck-but improvements to skin texture and radiance are still desired.

For these areas Dr. Kellett said she has been using a category of HA products from Galderma known as Skinboosters to improve skin quality.

"There are two groups of patients that we use [Skinboosters] for. The first would be an older patient who has retained volume," said Dr. Kellett. "They do not need volume, they do not need structure. They just want to improve the surface of the skin."

"The second group, which is a passion of mine, is in the treatment of scars, particularly acne scars."

Acne scar treatment
Dr. Kellett usually treats patients with the Skinbooster products over three sessions, one month apart, and then follows up after six months, she said.

Administration of Skinboosters is very different than HA products intended to add volume and contour. Rather than creating a bolus at a point or creating a line, these products are distributed in 0.01 cc microdroplets over a wider area.

"My favourite technique with this product is to use it with a cannula," Dr. Kellett said.  "The injection sites are one centimetre apart, so it is used as a field treatment. You are treating the entire neck or the entire cheek, not going after a line." She noted that she lays down a grid of microdroplets which then coalesce into a uniform sheet of material.

This sheet of HA then hydrates the superficial skin. "That is why it improves the smoothness, the elasticity, and the appearance of the skin," she said.

Atrophic acne scars are notoriously difficult to treat, Dr. Kellett said, with laser resurfacing and chemical peels being two modalities with some efficacy.

However, "some patients do not want [laser resurfacing or chemical peels], and some practitioners do not have lasers in their office," she noted.

In her own practice, Dr. Kellett decided to try combining the Skin Boosters she had been using in aged skin with subcising atrophic acne scars. "I use a cannula. I put a hole on the zygoma and one lower down on the mandible, and I subcise the whole cheek."

"In acne scars and atrophic scars, traditionally, we have been injecting conventional HA fillers. The problem with that is this: we are used to using traditional fillers in normal skin, and acne scars are not normal skin. They are fibrotic."

Often when an HA filler is used to try and elevate an atrophic acne scar, she said, the filler would pool around the trapped fibre. "So not only did you have the atrophic scar, now you had a bump of product beside the scar." It is necessary to break up the abnormal bands of collagen in the scars in order to correct them, she said.

"What I did is I took the cannula and I broke up the adhesions on the whole cheek," Dr. Kellett said. She takes the product and opens up a plane of tissue with the cannula, and injects a series of microdroplets to form a sheet of product.

"It is a great option for people who do not want laser, or they have type 6 skin," she said, noting the risk of post-inflammatory pigment changes from laser resurfacing on dark skin tones.

For acne scar correction, Dr. Kellett treats patients once a month for three months, and then follows up in six months.

"It is a great option, because they are getting an improvement not only from the product itself but from the nature of doing the subcision."