Intra-articular Therapies for Knee Osteoarthritis: Current Update

Purpose of the reviewThis narrative review highlights recent literature pertaining to available intra-articular (IA) therapeutics such as corticosteroids, hyaluronic acid (HA), platelet-rich plasma (PRP), stem cells therapy, and prolotherapy for knee osteoarthritis (OA) by summarizing recently published treatment guidelines and clinical trials, and discusses opinion and future directions.Recent findingsIA corticosteroid has questionable long-term efficacy in head-to-head comparisons with IA PRP, ketorolac, or normal saline. Combination therapy of IA corticosteroid plus HA may be more effective than a single IA corticosteroid therapy. Significant symptomatic improvement for at least 6 months was detected for combined therapies of IA HA with PRP or diclofenac, compared with single IA HA therapy in small studies. Conflicting results were reported over IA PRP using a variety of comparators such as IA HA, ozone, and normal saline, as well as over IA stem cell therapies, urgently necessitating the standardization of PRP and stem cell products. Prolotherapy may be effective in single or combination regimes in small studies. None of the IA therapies demonstrated serious adverse effects, such as septic arthritis. These findings should be interpreted with caution as the included studies show conflicting results as well as several methodological flaws such as small sample size, short-term follow-ups, a lack of control group and absence of structural evaluations.Collectively, these studies have demonstrated the need for further confirmation studies and highlighted the issues of standardization of PRP and stem cell therapies, the placebo effects and cost-effectiveness of IA therapeutics.