Corticosteroid injection before exercise may yield no additional benefit in knee osteoarthritis

Intra-articular corticosteroid injection administered before exercise therapy did not appear to yield additional clinical benefit in patients with osteoarthritis of the knee, according to a new study.

Researchers in Denmark performed a randomized, blinded, placebo-controlled clinical trial to examine the potential benefit of an intra-articular corticosteroid injection compared with placebo injection before exercise therapy for knee osteoarthritis. Patients 40 years of age and older were recruited from an osteoarthritis outpatient clinic from Oct. 1, 2012, through April 2, 2014. All had radiographically confirmed clinical osteoarthritis of the knee, clinical signs of localized inflammation, and pain in the knee while walking.

Patients were randomly assigned to receive an intra-articular 1-mL injection with methylprednisolone acetate, 40 mg/mL, dissolved in 4 mL of lidocaine hydrochloride (10 mg/mL), or a 1-mL isotonic saline injection mixed with 4 mL of lidocaine hydrochloride (10 mg/dL). The exercise program began 2 weeks after the injection was given and lasted for 12 weeks.

The study's primary outcome was change at week 14 in the Pain subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire, which ranges from 0 to 100, with higher scores indicating more improvement. Secondary outcomes were changes in the other KOOS subscales and measures of physical function and inflammation. Measurements were performed at baseline, when exercise began at week 2, when exercise stopped at week 14, and at follow-up at week 26. The study results were published online March 30 by JAMA Internal Medicine.

One hundred patients were included in the intention-to-treat population, 50 in the intervention group and 50 in the placebo group. Sixty-one percent were women, and the mean age was 63.4 years. Forty-five patients in the intervention group and 44 patients in the placebo group completed the trial. At week 14, mean changes (SE) in the KOOS Pain subscale score were 13.6 (1.8) and 14.8 (1.8) in the intervention and placebo groups, respectively. The mean group difference of 1.2 points (95% CI, −3.8 to 6.2) was statistically insignificant (P=0.64). In addition, no statistically significant differences were seen in any of the secondary outcomes at any of the time points.

The authors noted that the corticosteroid dose used in the study was in the lower recommended range and that results may have been different with a higher dose. The addition of lidocaine may also have affected the response, they said. However, they concluded that based on their results, injection of corticosteroids before exercise therapy offered no additional benefit to patients with knee osteoarthritis. “Further research is needed to establish optimal and potentially synergistic combinations of conservative treatments of [osteoarthritis] of the knee,” they wrote.