Hyaluronic Acid and Filler Injections

Faced with the ever-growing demand for gentle aesthetic medicine techniques (non-surgical) aimed at combating the effects of ageing, the number and quality of injectable materials has evolved considerably in recent years and their use has become extremely frequent.

It was in 1934 that hyaluronic acid, or hyaluronan, a combination of a uronic acid and an aminoglycan, was discovered in bovine eye vitreous humour.

The exceptional properties of this molecule have determined its use in many medical specialties, notably ophthalmology (cataract surgery), ENT (vocal cord surgery), urology, and wound healing.

Since 1996, this molecule has been developed in the field of aesthetic filling.

With no species or tissue specificity, endowed with exceptional viscoelastic and hydrophilic properties, this polysaccharide requiring no preliminary testing before treatment has become, thanks to its qualities, the natural successor to injectable collagen in the treatment of wrinkles and depressions.

In ten years, this molecule has completely revolutionised the management of skin ageing. Product developments, their multiplication, and advances in injection techniques now make it the cornerstone of aesthetic filling treatments, volume restoration and revitalisation.

Hyaluronic acid is today considered the reference product used in medical volumetric rejuvenation thanks to:
• Its track record: in use, as we have seen, since the 1990s. • Its variable in-situ duration of 6 to 18 months: injections last long enough to be effective and their transient nature allows for ageing follow-up.
• Its lack of tissue specificity, making it biocompatible with tolerance tests not required before injection (except in special cases). • Its fully biodegradable character.
• Its ease of use, requiring no preparation.
• The breadth of its usable range: the same product can be formulated in different forms adaptable to different types of ageing.
• Its immediate results. • Its minimal and exceptional side effects.
• The possibility of injecting it in different forms allows optimal use of its qualities:
• Hydrating and revitalising in mesotherapy
• Correction of superficial wrinkles
• Correction of deep wrinkles and volumes

An injection session can be performed in isolation, but may also complement more radical medical-surgical rejuvenation techniques such as resurfacing (peeling, laser, dermabrasion), blepharoplasties (upper and/or lower eyelids), facelifts, etc. It may also be carried out in parallel with Botulinum Toxin injections aimed at reducing the tone of certain muscles responsible for wrinkle formation.

A hyaluronic acid injection aims to correct, through a simple and rapid means, certain signs of ageing or imperfections present at the facial level, by filling or adding volume where necessary.

The most frequently performed corrections can be divided into four categories:
• Furrows: nasolabial folds (from the nose wing to the mouth corner), marionette lines (from the mouth corner, on either side of the chin), labiomental furrow, etc.
• Wrinkles and fine lines: forehead, "frown lines" (between the eyebrows), "crow's feet" (at the eye corners), cheeks, chin, "sunburst" lines around the mouth.
• Lips: reshaping the vermilion border (contour), thickening thin lips, or making them more plump.
• Depressions (hollows) or volume deficiency: cheekbones, dark circles, chin, mandibular contour, cheeks, nose, temporal hollows, scar sequelae (acne, chickenpox, trauma, etc.)

Usually, these imperfections will not completely disappear but will be considerably attenuated by the injections. Some alterations respond much better to treatment than others. Similarly, the durability of correction varies according to the type of hyaluronic acid and the patients, but the correction is only temporary and treatment must be renewed to maintain the result.

It should be noted that many other alterations may be present, but their treatment is only possible using medical-surgical techniques more complex than simple injections. This is particularly true of tissue sagging (e.g., jowls) and skin excess (e.g., eyelids) that can only be removed surgically. Similarly, certain skin anomalies (rough patches, small scars, blemishes, micro-wrinkles, "crinkled" skin) can only be corrected by resurfacing (peeling, laser, dermabrasion).

Injections, performed on both women and men, can be carried out from age 30-35. However, they are sometimes performed much earlier when the imperfections are constitutional or hereditary rather than age-related (lips, cheekbones, etc.).

The basic principle is to inject the product into the skin thickness or deeper, to correct certain wrinkles or facial depressions and age-related volume losses.

There are today a large number of hyaluronic acids available on the market, bearing the CE (European Community) mark.

These products differ notably by their viscosity, which determines their more or less volumising character.

Among the most widely used are Juvederm, Surgiderm, Restylane, Perlane, Stylage, Teosyal, Voluma, Emervel, etc.

For significant volumetric correction (cheekbones, chin, etc.) or in allergic patients, the merits of autologous fat re-injection should be discussed with your practitioner (cf. the information sheet: autologous fat re-injection or lipofilling or lipostructure).

A precise interview will be conducted to identify any contraindications:
• Known hypersensitivity to hyaluronic acid
• Pregnant or breastfeeding women.

The interview must also detect elements requiring particular caution (e.g., herpes for lip and perioral injections) or clarify the nature of any previous injections to avoid certain dangerous product combinations at the same site.

Aspirin or anti-inflammatory medications should be avoided in the 3 days before the injection.

It is preferable not to drink alcohol or expose yourself strongly to the sun the day before and the day of the session.

A careful clinical examination, conducted in a seated position, is compared with the patient's request and expectations to specify what is achievable and what is unrealistic.

It is helpful to use comparison with "younger photographs."

This examination allows specification of areas requiring a volumising hyaluronic acid or a more superficially acting product, to establish a "map" with the patient, and to propose a treatment plan, often noted on a diagram.

Schematically, depending on face shape: round, long, intermediate:
Round faces: in addition to wrinkles and furrows, correction of the mandibular and para-chin line will complement surgery to treat and maintain the facial oval.
Long faces: the ideal indication for more or less concentrated products:
"Thick," "cohesive" products for:
• temples, cheekbones, para-chin regions, cheeks, nasolabial folds
"Medium," more "fluid" products:
• to soften volumes (cheeks, para-chin regions) previously treated, • to complement deep correction more superficially (nasolabial fold),
• to rejuvenate the orbital or lip region.
"Intermediate" face: the above indications are combined to varying degrees.

Injections can be performed without anaesthesia, especially as many products are now supplied with a local anaesthetic in the syringe.

However, for some slightly more painful products, in particularly sensitive patients, or in certain difficult areas (lips and perioral region), one of two existing methods can be planned:

• Emla cream: applied in a thick layer on the areas to be treated at least one hour before injection, it reduces painful sensations on the surface.

• True local anaesthesia: obtained by injection of an anaesthetic product at the start of the session, it alone ensures total insensitivity.

The area to be treated is disinfected before injection.

Injections are performed using needles or micro-cannulas.

Depending on the practitioner, the number of areas to treat, the extent of improvements to be made, and the possible need for anaesthesia, the injection session may last from 10 minutes to 1 hour.

In practice, several injection techniques exist and each physician will adopt a method of their own, adapted to each case to achieve the best results.

Treatment is often performed in several superimposed layers ("strata") to achieve an optimal result.

The amount of product needed (number of syringes) is of course extremely variable depending on numerous parameters. It will be evaluated as precisely as possible beforehand.

After injection, the practitioner takes care to massage the treated areas thoroughly to optimise the uniformity of the correction.

In some cases, it is preferable to plan a touch-up session from the outset, after a few days or weeks, to perfect the result.

When several areas are treated in the same session, the results are:
• More visible (global rejuvenation).
• More harmonious (fewer differences between different facial areas).
• The face will remain more balanced as the injected products are reabsorbed.

The most common indications for hyaluronic acid injections are:
• Wrinkles, fine lines and furrows of the face and neck,
• Lips, which can be reshaped, thickened, made more plump.
• Age-related depressions and volume losses.

Other indications also exist:
• Certain moderate morphological anomalies (receding chin, insufficient cheekbone or forehead projection, nasal irregularities, etc.)
• Skin anomalies (scar sequelae, depressed and irregular scars)
• Body deformities or minor volume insufficiencies.

For the first six hours, it is better to remain calm, rest and avoid any strenuous effort. It is also advisable to avoid moving your face as much as possible (no facial expressions, not too much talking or laughing).

For a few days, it is preferable to avoid alcohol, aspirin, anti-inflammatory drugs, and to avoid exposing the treated areas to intense heat (sun, UV, sauna, hammam).

Immediate aftereffects may possibly include the appearance of oedema (swelling) and skin redness whose severity and duration are highly variable depending on the products and from one individual to another, but which usually remain moderate (not preventing a rapid return to normal socio-professional life) and disappear within one to three days. On the lips, however, the oedema, often more marked, may sometimes last a full week.

More rarely, during the first days at the injection points, some skin sensitivity, itching, skin pallor, hyperpigmentation, or small punctuate ecchymoses (bruising) may be observed.

It should be noted that during the first days, some temporary irregularities due to uneven oedema distribution, or an appearance of over-correction (in relief) that will gradually disappear, may exist.

A few days are necessary to appreciate the definitive result. This is the time needed for the product to integrate well, for oedema to disappear, and for tissues to regain all their suppleness.

The immediate post-treatment result is therefore not a reflection of the final result.

The injections will have corrected imperfections, thus discreetly and naturally rectifying the aged and tired appearance of the face. Note that filler injections, unlike Botulinum Toxin injections, do not alter the mobility of facial muscles and therefore do not reduce facial expressions.

Usually, the treated imperfections are very noticeably attenuated by the injections, but do not always completely disappear. Indeed, some locations are particularly difficult to treat and there are deep, long-standing wrinkles that can never be completely erased.

The goal of these injections is to bring about an improvement, not to achieve perfection. If your expectations are realistic, the result obtained should give you great satisfaction.

We have seen that the duration of action is extremely variable depending on the products (resorbable or not), but also on the areas to treat (less durable on the lips), the injection technique, and the patients depending on skin type, lifestyle (stress, smoking, alcohol, sun, etc.) and the degree of perfection sought. In most cases, however, the correction is only temporary and treatment must be renewed to maintain the result.

Possible undesirable side effects:

Any medical act, however minor, involves a degree of uncertainty and risk.

By choosing a qualified practitioner specifically trained in these injection techniques, you limit these risks, particularly as hyaluronic acid is a product remarkably well tolerated by human tissues.

A number of reactions may however be observed:

Post-injection local reactions: as we have seen, oedema, redness, pallor, irregularities, sensitivity, itching, and ecchymoses may sometimes occur. These reactions are however only temporary.

Labial herpes flare-up: in predisposed individuals.

Acute or chronic inflammatory reaction: possible after secondary injection into an area previously injected with other products, particularly non-resorbable ones.

Granulomas: although rare, this is the most "classic" complication. These are small indurated nodules, more or less tender, palpable, sometimes visible and unsightly. They correspond to a localised inflammatory reaction that may evolve in flares. They may appear a few days to a few weeks after injection. These granulomas are in fact extremely rare with resorbable products, and even exceptional with hyaluronic acids. They are moreover spontaneously regressive within a few weeks.

Extremely rare complications: a few cases have been described of redness persisting for several weeks, abscess or skin necrosis, localised at an injection point.

Overall, risks should not be overestimated, as they remain minimal after hyaluronic acid injection.

Indeed, thanks to its unparalleled physicochemical qualities and tolerance, hyaluronic acid occupies a preponderant, currently undisputed position not only in the field of filling but also in volume restoration and hydration.

One should simply be aware that a filler product injection, even apparently simple since non-surgical, always involves a small element of uncertainty.

Choosing a qualified practitioner ensures that the practitioner has the training and competence required to try to avoid these problems, or to treat them effectively should they arise.

It is important that you carefully note, at the end of each injection session, the nature of the injected product so that you can inform any other practitioner who may subsequently take over your care.