Corticosteroid Injections for Symptomatic Treatment of Osteoarthritis of the Knee: A Pilot Blinded Randomized Trial

To quantify the effect of corticosteroids compared to lidocaine-only injections over 12 weeks among patients with knee osteoarthritis (KOA).

Participants with KOA were randomized to receive a knee injection of methylprednisolone acetate 1 mL (40 mg) plus 2 mL lidocaine (1%) or 1 mL saline and 2 mL lidocaine. Participants and providers were blinded to treatment allocation using an opacified syringe. The outcome was the average change from baseline of the total Knee Injury and Osteoarthritis Outcome Score (KOOS) (range 0-100) assessed at 2-week intervals over 12 weeks. Participants received KOOS questionnaires on their smartphones through a web-based platform. We used linear mixed-effects regressions with robust variance estimators to evaluate the association between the intervention and change in KOOS total and subscales (ClinicalTrials.gov identifier NCT03835910; registered 2019-02-11).

Of the 33 randomized participants, 31 were included in the final analysis. The predicted mean (SE) change in total KOOS over the 12-week follow-up was 9.4 (3.2) in the corticosteroids arm versus -1.3 (1.4) in the control arm (P = 0.003). Of participants, 47% achieved change as large as the minimal clinically important difference (16 units) in the intervention arm compared to 6% of participants in the lidocaine arm. Further, there were greater improvements in the intervention arm for KOOS subscales and for Patient Reported Outcomes Measurement Information System (PROMIS) assessments of pain intensity, behavior, and interference.

Corticosteroid injections demonstrated clinically meaningful improvements in KOA symptoms over 12 weeks of follow-up. These data support larger studies to better quantify short-term benefits.