How does viscosupplementation compare with NSAIDs or intraarticular corticosteroid injections?
The role of viscosupplementation in knee OA is controversial. Some clinical trials suggest that pain relief is equivalent to NSAIDs without the gastrointestinal side effects. More recently, metaanalyses of double-blind controlled trials have shown no greater relief than placebo “sham” injections (of interest, other studies have shown that placebo injections have an equal effect size for clinical benefit compared with NSAIDs for knee OA). A direct comparison of viscosupplementation to intraarticular corticosteroids shows that they are relatively equivalent to each other for knee OA. Corticosteroids have been shown to provide benefit earlier following injection, with a small statistical edge for viscosupplementation at 6 months. Because of a difference in cost, some physicians will use intraarticular corticosteroids before going to viscosupplementation. Intraarticular corticosteroids are thought to be more effective in patients with knee OA causing an effusion (“wet OA”), which suggests a mild inflammatory component. Recent data from a randomized controlled trial has raised concern for progressive joint space narrowing with repeated steroid injections in comparison to saline; as such, a reasonable approach may be to consider steroid injections in patients with “wet OA”, in those who have received lasting benefit from injections in the past, and in patients who have exhausted other therapy options. A similar conservative approach with viscosupplementation would be reasonable given the cost of medication. An extended-release formulation of triamcinolone acetonide (Zilretta) is FDA-approved for OA and is characterized by prolonged latency in the synovial tissue and decreased systemic absorption (decreased blood sugar elevation among diabetics in one study), at a cost of $600 per injection (compared with $10 per injection of 40 mg standard triamcinolone).