From the Guidelines
Injecting hyaluronic acid (HA) is not consistently supported by high-quality studies for the treatment of knee osteoarthritis, and its use is conditionally recommended against in patients with knee OA, according to the most recent evidence 1. When injected into the skin as a dermal filler, HA temporarily reduces wrinkles, enhances facial contours, and restores volume loss for 6-18 months depending on the specific product and injection site. For joint injections, HA supplements the natural joint fluid, improving lubrication and shock absorption to reduce pain and improve mobility in conditions like osteoarthritis, typically lasting 3-6 months. The procedure involves cleaning the injection site, possibly applying topical anesthetic, and using a fine needle to place the HA in the target area. Some key points to consider when injecting HA include:
- Side effects are generally mild and temporary, including swelling, bruising, redness, and tenderness at the injection site.
- HA works effectively because it's naturally found in the body, particularly in skin and joint fluid, making it biocompatible with minimal risk of allergic reactions.
- The body gradually breaks down injected HA over time through normal metabolic processes.
- The current evidence does not identify the subset of patients who benefit from HA, which may explain the observed inconsistency in the evidence 1.
- The use of HA injections in the knee OA patient who has had an inadequate response to nonpharmacologic therapies, topical and oral NSAIDs, and intraarticular steroids may be viewed more favorably than offering no intervention, particularly given the impact of the contextual effects of intraarticular hyaluronic acid injections 1.
From the Research
Effects of Hyaluronic Acid Injection
- Hyaluronic acid (HA) is a naturally occurring component of skin, and its injection improves wrinkles and volume loss by filling, volumizing, and hydrating the injected area 2.
- The injection of HA has a negligible risk of immunologic or allergic reaction, and it is rapidly degraded by the injection of hyaluronidase, making it a low-risk and reversible injectable material 2.
- HA injection can stimulate collagen synthesis or fibroblast stimulation, which may lead to a longer duration of effect than expected based on its bioavailability 2.
Physiological Effects of Hyaluronic Acid Injection
- Intradermal injection of native hyaluronic acid can improve skin elasticity and reduce skin surface roughness in aged skin 3.
- High-frequency ultrasound has shown an increase in skin thickness after HA injection, while skin density decreases during treatment and slightly increases above baseline at week 24 3.
Potential Risks and Complications
- Although HA fillers have a satisfactory safety profile, adverse reactions can occur, and rare cases of intravascular injection may lead to blindness 4.
- A systematic review of high-level evidence studies found that most adverse events associated with HA filler injection are short-lived injection site reactions, while severe adverse events are rare but can persist for months and require active medical intervention 5.
- Specific HA fillers and injection techniques can influence the occurrence of adverse events, which generally resolve within weeks without treatment 5.
Precautions and Contraindications
- Caution should be used in long-term treatment with oral compounds of hyaluronic acid in patients with a history of cancer, as HA can interact with specific receptors and promote cell proliferation, potentially hazardous in cancer patients 6.