Edited by Shrabasti Bhattacharya
Medscape Medical News
TOPLINE:
Glucocorticoid injections into the infrapatellar fat pad did not significantly reduce knee pain or effusion synovitis volume compared with placebo over 12 weeks in patients with inflammatory knee osteoarthritis (OA); however, the treatment group showed improvements in certain pain measures and cartilage defect scores.
METHODOLOGY:
- Researchers conducted a clinical trial at four centers in China to evaluate the efficacy and safety of glucocorticoid injections into the infrapatellar fat pad in patients with inflammatory knee OA.
- They enrolled 60 patients (mean age, 64.9 years; 63.3% women) from April 2022 to June 2023 and randomly assigned them to receive either glucocorticoid (n = 30) or saline (n = 30) injections into the infrapatellar fat pad; both groups received hyaluronic acid as background treatment under ultrasonographic guidance.
- Individuals were eligible if they were aged 45 years or older, met American College of Rheumatology criteria for symptomatic knee OA, had knee pain for more than 6 months with a visual analog scale (VAS) score ≥ 40 mm in the prior week, and had MRI-assessed Hoffa synovitis and effusion synovitis scores of ≥ 1 each along with a combined score of ≥ 3.
- Primary outcomes included changes in knee pain and effusion synovitis volume assessed via the VAS and MRI, respectively; outcomes were assessed over 12 weeks.
TAKEAWAY:
- The average reduction in VAS pain scores from baseline to 12 weeks was 39.3 points (95% CI, 27.5-51.1) in the treatment group and 31.4 points (95% CI, 19.7-43.1) in the placebo group; however, the between-group difference was not significant (P = .19).
- The reduction in effusion synovitis volume from baseline to 12 weeks was 4.9 mL (95% CI, 2.0-7.8) in the treatment group and 5.4 mL (95% CI, 2.5-8.3) in the placebo group, yielding a nonsignificant difference between the two groups (P = .67)
- Post hoc analyses revealed significantly greater reductions in the Western Ontario and McMaster Universities Osteoarthritis Index pain score (P = .04) and cartilage defect scores (P = .03) in the treatment group.
- At least one adverse event was experienced by 10% of participants in the treatment group compared with 23.3% in the placebo group.
IN PRACTICE:
“Among patients with knee OA and effusion synovitis and Hoffa synovitis, glucocorticoid injections into the IPFP [infrapatellar fat pad] did not significantly alleviate pain or reduce effusion synovitis volume over 12 weeks,” the authors wrote.
SOURCE:
This study was led by Yan Zhang, PhD, Clinical Research Center, Zhujiang Hospital, Southern Medical University in Guangzhou, China. It was published online on January 2, 2025, in JAMA Network Open.
LIMITATIONS:
The 12-week duration was inadequate for assessing structural changes such as infrapatellar fat pad atrophy and cartilage loss. The sample size was determined based on the minimum clinically important difference, which may have resulted in the study being underpowered to detect more modest but clinically relevant differences between groups. Although both groups received intra-articular hyaluronic acid equally, patients’ awareness of possibly getting an active treatment may have increased placebo effects.