The intra-articular injection of hyaluronic acid is also known as viscosupplementation, referring to the visco-elastic properties of this substance.
, formed by the repetition of a disaccharide consisting of N-acetylglucosamine and glucuronic acid, with a high molecular weight (4-6 million daltons) and high viscosity.
Produced by type B synovial cells (the cells of the synovium), hyaluronic acid is an important component of the synovial fluid, where it helps to lubricate the joint and to cushion mechanical stress (lubricating and shock-absorbing function). In addition, it protects the cartilage from the penetration of inflammatory cells and from the lytic enzymes that degrade it.
In patients suffering from arthrosis it is also possible to observe - among other things - a decrease in the viscoelastic properties of the synovial fluid, associated with a reduction in the synthesis and molecular weight of intra-articular hyaluronic acid. Hence the rationale for the use of hyaluronic acid infiltrations directly into the arthritic joint, to which benefits such as:
- alleviation of pain, improvement of joint mobility and prevention of cartilage degradation with improvement of daily living activities
- anti-inflammatory effect, with reduction of intra-articular effusion
- reconstruction of the superficial amorphous layer of cartilage
- increased density of chondrocytes (cartilage cells)
- clinical efficacy for at least 6 months - 1 year after the course of infiltrations
However, not all studies agree on the efficacy of hyaluronic acid infiltration in the conservative treatment of osteoarthritis. Some meta-analyzes have even demonstrated an efficacy that is only slightly superior to placebo. Other studies have established that hyaluronic acid infiltrations produce a pain reduction comparable to that of intra-articular injections of cortisone. For this reason, some doctors warn against the excessive emphasis on this treatment: currently there is no cure that is certainly and always effective in the treatment of osteoarthritis. Conservative options include the use of anti-inflammatory drugs, analgesics, steroids, chondroprotectors and physiotherapy interventions; in this context, hyaluronic acid infiltrations can be validly used in the treatment of common painful pathologies linked to degenerative joint conditions typical of osteoarthritis.
of the skin, replacement of the needle after aspiration of the drug), the infiltrations of hyaluronic acid are safe and well tolerated. In the infiltration site, pain, swelling, sensation of heat and redness may arise. Poly-allergic individuals may experience systemic effects with hypersensitivity and anaphylactoid reactions.
