Injections in the osteoarthritic knee: a review of current treatment options

Knee osteoarthritis is a degenerative condition characterized by progressive cartilage degradation, subchondral damage, and bone remodelling. Among the approaches implemented to achieve symptomatic and functional improvements, injection treatments have gained increasing attention due to the possibility of intra-articular delivery with reduced side effects compared to systemic therapies. In addition to well-established treatment options such as hyaluronic acid (HA), cortico-steroids (CS) and oxygenozone therapy, many other promising products have been employed in the last decades such as polydeoxyribonucleotide (PDRN) and biologic agents such as plateletrich plasma (PRP) and mesenchymal stem cells (MSCs). Moreover, ultrasound-guided intra-meniscal injection and X-ray-guided subchondral injection techniques have been introduced into clinical practice. Even when not supported by high evidence consensus, intra-articular CS and HA injections have gained precise indications for symptomatic relief and clinical improvement in OA. Biological products are strongly supported by in vitro evidence but there is still a lack of robust clinical evidence. PRP and MSCs seem to relieve OA symptoms through a regulation of the joint homeostasis, even if their capability to restore articular cartilage is still to be proved in vivo. Due to increasing interest in the subchondral bone pathology, subchondral injections have been developed with promising results in delaying joint replacement. Nevertheless, due to their recent development and the heterogeneity of the injected products (biologic agents or calcium phosphate), this approach still lacks strong enough evidence to be fully endorsed. Combined biological treatments, nano-molecular approaches, monoclonal antibodies and 'personalized' target therapies are currently under development or under investigation with the aim of expanding our armamentarium against knee OA.

Automated summary

Knee osteoarthritis can be treated with injection therapies such as hyaluronic acid and cortico-steroids, as well as promising products like polydeoxyribonucleotide and biologic agents. While biological products have strong in vitro evidence, there is still a lack of robust clinical evidence for their effectiveness in treating OA symptoms. Emerging treatments including combined biological therapies and nano-molecular approaches are currently under development to expand the options for knee OA treatment.