Arthritis is affecting millions of people globally, involvement and distribution depending on the type of arthritis. The most common arthritic conditions are osteoarthritis (OA) and rheumatoid arthritis (RA). Despite the pathogeneses being fundamentally different, both joint diseases share the same need for local treatment of synovitis. No current treatment can stop the progression of OA. Local articulate treatment including glucocorticoid (GC) injections, radiosynoviorthesis (RSO) and surgical synovectomy are the only options to relieve pain and temporally improve movability before surgical intervention. For RA, despite effective systemic treatments, similarly need for local articulate treatment is still present, especially early in the disease, but also in case of recurrent episodes of disease flare. Current evidence supports local GC injection as first line treatment for persistent synovitis in a single or a few joints. RSO provides an evident and effective alternative for GC refractory synovitis, especially in early RA. Surgical synovectomy is an invasive alternative, but with less documented efficacy. Whether one unsuccessful intraarticular GC injection is enough to change of mode of action for local treatment is still unclear and needs to be further investigated. In conclusion persistent single joint synovitis in OA and RA is well treated with local treatment. Intra-articular GC injection is considered as first line of treatment, but RSO provides an additional treatment alternative with less side effects and better evidence of efficacy than surgical synovectomy.