Intra-articular hyaluronic acid (HA) injections for the symptomatic relief of pain have been available for treatment since the 1980s. Practitioner experience and real-world evidence have been accumulated to suggest that HA injections are effective and well tolerated in patients. Treatment guidelines issued by different professional medical societies, however, do not point in a single direction. This appears mainly due to conflicting results of the proposed meta-analyses at least in part associated with a variability between different HA preparations on different outcome parameters, suggesting that intra-articular HA products should not be treated as a group, as there are differences between them influencing both efficacy and safety.
The present review is focused on the quite relevant amount of preclinical and clinical studies (the first studies dating back to thirty years ago) concerning a specific HA-based preparation (500-730 kDa native HA) and supporting its use as a tool for intra-articular therapy. They also include comparative studies to other HA preparations.
The analysis of this experience allows to define a specific profile for 500-730 kDa HA as a tool for the management of osteoarthritis in terms of main mechanism of action, kinetics features and interaction with joint tissues, subpopulation of patients expected to obtain the highest benefit from the treatment, safety issues and impact on disease-cost.
The abovementioned factors may also represent useful criteria to better characterize the specificities of each HA-based preparation and to achieve a more stratified categorization of this class of therapeutic tools.