What is the role of hyaluronic acid (HA) in the human body?

From the Guidelines

Hyaluronic acid injections are not recommended for routine use in the treatment of symptomatic osteoarthritis of the knee, as the current evidence does not consistently support its effectiveness. According to the most recent and highest quality study, 1, the strength of this recommendation is moderate, implying that practitioners should generally follow this guideline but remain alert to new information and be sensitive to patient preferences.

Key Points to Consider

• The evidence from high-quality studies, such as 1 and 1, suggests that hyaluronic acid injections do not provide a significant benefit for patients with knee osteoarthritis.
• The American Academy of Orthopaedic Surgeons recommends against the routine use of hyaluronic acid injections for symptomatic osteoarthritis of the knee, as stated in 1 and 1.
• While some patients may still benefit from hyaluronic acid injections, the current evidence does not identify a specific subset of patients who would benefit from this treatment, as noted in 1.

Clinical Implications

• Practitioners should consider alternative treatments for osteoarthritis of the knee, such as weight loss, exercise, and oral nonsteroidal anti-inflammatory drugs (NSAIDs), which have been shown to be effective in improving pain and function, as discussed in 1.
• Patients who have tried other treatments without adequate relief may still be considered for hyaluronic acid injections, but this should be done on a case-by-case basis, taking into account the patient's preferences and the potential risks and benefits, as suggested in 1.

From the Research

Hyaluronic Acid Properties and Uses

• Hyaluronic acid (HA) is a naturally occurring biopolymer with a highly conserved molecular structure between mammalian species 2.
• HA plays a multifaceted role in regulating various biological processes, including skin repair, wound healing, tissue regeneration, anti-inflammatory, and immunomodulation 3.
• It has been used in various medical fields, including neurosurgery, cutaneous wound healing, and cosmetic practice 2.

Cosmetic and Nutricosmetic Applications

• HA has been employed as a component of cosmetic and nutricosmetic products due to its remarkable biomedical and tissue regeneration potential 3.
• HA-based formulations exhibit anti-wrinkle, anti-nasolabial fold, anti-aging, space-filling, and face rejuvenating properties 3.
• The application of HA, alone or in combination with other agents, has shown promising efficacy in skin tightness and elasticity, face rejuvenation, and improving aesthetic scores 3, 4.

Clinical Evidence and Studies

• A systematic review of the English language literature provided an overview of the scientific evidence for HA use in wound healing and cosmetic practice 2.
• Studies have demonstrated the effectiveness of HA fillers in facial rejuvenation and enhancement of facial features 5, 4.
• A clinical and ultrasonography analysis showed that a combined technique with HA and calcium hydroxylapatite fillers improved facial skin laxity and dermal thickness in women with mild midface aging 4.

Biological Effects and Safety

• HA has moisturizing and anti-aging effects on the skin, and its molecular weight influences its penetration and biological activity 6.
• The biological effect of HA on the skin level and its potential adverse effects have been discussed in various studies 6.
• Local adverse effects of HA fillers have been reported to be mild and transient 4.