Commentary

The biological mechanism of corticosteroids suggests that they should be effective in joint disease with significant inflammation—a fact established in the treatment of rheumatoid arthritis. However, how beneficial are corticosteroids in such conditions as OA? The meta-analysis by Arroll et al provides the best answers to date: (1) Intra-articular steroids are modestly better than saline for short term relief of pain. Patients who receive intra-articular corticosteroids are 1.6 times more likely to improve at 2 weeks than those who receive placebo injections (number needed to treat [NNT] = 4). This conclusion is robust, given the results of previous studies,¹ the tendency of OA to worsen over time, and the consistency of the findings of this review (7 of 10 trials showed improvement). (2) Corticosteroids appear to have slight benefit at 16–24 weeks (NNT = 5). However, this conclusion was based on only 2 trials, is less consistent with the clinical experience of rheumatologists, and may be dose dependent.

The review by Arroll et al also raises several questions: which group of OA patients are likely to respond to corticosteroids (ie, those with less severe disease or those with clinical evidence of inflammation such as an effusion)? To what degree is the apparent success of intra-articular steroids affected by how the procedure is performed? For example, how much fluid is withdrawn if lavage is used rather than saline instillation? At what point in the treatment regimen should intra-articular corticosteroids be used (ie, after or before NSAID or physical therapy)? What is the effective and safe interval for repeat injections?

Unless or until further studies address these issues, clinicians should be reassured that with prudent use, intra-articular corticosteroids remain a valuable option for short term management of OA of the knee.