Evidence of the clinical effect of commonly used intra‐articular treatments of equine osteoarthritis

Summary Background Osteoarthritis (OA) is a common disease in equine patients that causes joint pain and loss of function. The aetiology of OA is assumed to be multifactorial. A range of medical treatments are on the market for symptomatic treatment of OA in equine patients, both biological and conventional options. Today, no true disease‐modifying osteoarthritis drug (DMOAD) is available. Objective To summarise the current evidence of the clinical effect of commonly used intra‐articular treatments of equine OA, specifically the use of intra‐articular glucocorticosteroids (IA‐GCs), intra‐articular hyaluronic acid (IA‐HA), intra‐articular platelet‐rich plasma/autologous‐conditioned plasma (IA‐PRP), intra‐articular interleukin‐1 receptor antagonist protein/autologous‐conditioned serum (IA‐IRAP) and intra‐articular mesenchymal stem cells (IA‐MSCs). Study design Systematic review. Methods Using the Preferred Reporting Items for Systematic Reviews and Meta‐Analysis (PRISMA) guidelines, a comprehensive search identified 22 clinical studies where horses with OA, naturally occurring or induced, were treated with one of the mentioned intra‐articular treatments. The studies were reviewed to collect all in vivo studies with clinical follow‐up on horses with OA. Results IA‐GCs seem to have a beneficial short‐term clinical outcome. Treatment with IA‐HA shows varying clinical results and provides uncertain evidence for a beneficial clinical effect. IA‐PRP shows overall promising clinical results for a significant improvement. IA‐IRAP shows promising significant clinical effect, but most of the studies lack a control group for comparison. IA‐MSCs show varying clinical results, but a majority of the included studies show evidence for a significant improvement in clinical effect. Conclusion To provide stronger evidence of the clinical effect of the five chosen treatments, further blinded, randomised and placebo‐controlled studies are needed.