Fig. 1

Knee pain as measured on the P4 instrument before and after knee joint aspiration and corticosteroid injection. Baseline = before intervention. Day 5 = 5 ± 2 days after knee joint aspiration and corticosteroid injection. Day 15 = 15 ± 2 days after knee joint aspiration and corticosteroid injection. **= significant change from baseline (p <0.01). ***= significant change from baseline (p = 0.001). Data are means and one standard error of the mean