The hyaluronic acid is a glycosaminoglycan in the dermis and epidermis, accounting for about 1 percent of the skin’s dry weight. It binds and retains water. This humectant occurs naturally in the extracellular matrix, in high concentrations in the dermis (around 50 percent) and in the eye and joints. It plays a key role in skin hydration. With the capacity to hold up to 1,000 times its weight in water, it maintains skin suppleness and supports proper hydration. It contributes to dermal structure by interacting with the collagen and elastin, which helps preserve skin firmness and elasticity. It promotes cell regeneration and has antioxidant properties that help counter oxidative stress.
However, its level declines with age. Specialists estimate a child’s level is twice a 50-year-old adult’s. This loss leads to skin dehydration and reduced volume.
The hyaluronic acid used in injections is derived from a biotechnological synthesis via fermentation of natural bacteria, such as Streptococcus equinus, Streptococcus zooepidemicus, or Bacillus subtilis. When injected into the skin, it improves skin hydration and elasticity, restores volume and strengthens the skin barrier against external stressors. When administered to the backs of the hands, it acts as a volumising agent by filling depressions and restoring tissue density. It causes a slight swelling for natural skin plumping.
A study of 16 patients with an average age of 60 years assessed the efficacy of hyaluronic acid injections for the rejuvenation of hollow hands. Participants received a single injection of SGP-HA, a viscous gel containing 20 mg/ml of hyaluronic acid obtained by bacterial fermentation (Streptococcus). The injection was administered on the back of the hand, followed by a massage towards the fingers for uniform distribution. The volume injected was 4 ml per hand, with an optional top-up of 1 ml two weeks later to optimise results. Several follow-up visits were scheduled, the last one occurring one year after the initial treatment. Two weeks after injection, a marked improvement in hand appearance was observed in most patients, with sustained outcomes over time: 85% satisfaction at six months, although this rate fell to 50% after one year.