Clinical Question

Is an intramuscular glucocorticoid injection noninferior to an intra-articular glucocorticoid injection in reducing knee pain in adults with knee osteoarthritis?

Bottom Line

This study found that intra-articular glucocorticoid injection may work better for reducing pain from knee osteoarthritis at one month, but there was no significant difference in pain resolution between intra-articular injection and intramuscular injection at two months or six months. (Level of Evidence = 1b)

Synopsis

Intra-articular glucocorticoid injections are associated with greater cartilage loss and a rare but increased risk of joint infections and septic arthritis. The investigators identified adults (N = 145), 45 years and older, with knee osteoarthritis diagnosed by their primary care physician, presence of symptomatic knee osteoarthritis for at least three months, and moderate to severe knee pain over the past week (i.e., at least 3 on a scale of 0 to 10; 0 indicates no pain). Eligible participants randomly received (concealed allocation assignment) an intramuscular injection (40 mg triamcinolone acetonide) in the gluteal region or the same drug and dose given as an intra-articular injection in the index knee. Patients self-reported severity of knee pain at two, four, eight, 12, and 24 weeks after treatment using a previously validated knee pain scoring tool (0 to 100; 0 indicates extreme pain). Although the minimum clinically important difference for this tool is 9, the investigators chose to prespecify the noninferiority margin at 7. Per-protocol data were available for 138 (95%) of participants at 24 weeks.

Using per-protocol and intention-to-treat analyses, noninferiority could not be declared at four weeks because the lower limit of the 95% CI exceeded the noninferiority margin for intramuscular vs. intra-articular injections (−3.4; 95% CI, −10.1 to 3.3). However, intramuscular injection was declared noninferior to the intraarticular injection at eight weeks and 24 weeks. The investigators reported multiple secondary outcomes, all of which showed that the intramuscular injection was most effective at eight weeks after injection, the intra-articular injection was most effective at four weeks, and there were no significant group differences at any time points.

Study design: Randomized controlled trial (single-blinded)

Funding source: Foundation

Allocation: Concealed

Setting: Outpatient (primary care)

Reference: Wang Q, Mol MF, Bos PK, et al. Effect of intramuscular vs intra-articular glucocorticoid injection on pain among adults with knee osteoarthritis: the KIS randomized clinical trial. JAMA Netw Open. 2022;5(4):e224852.