The Effects of Ultrasound-Guided Genicular Nerve Blocks Used with Local Anesthetics Alone or in Combination with Corticosteroids on Patients with Knee Osteoarthritis: A Placebo-Controlled Randomized Clinical Trial.

Abstract

The genicular nerve block (GNB) is an emerging minimally invasive treatment for knee osteoarthritis (OA) pain. While corticosteroids are often combined with local anesthetics in GNBs, the added clinical value of this combination remains unclear. To evaluate the efficacy of the GNB with local anesthetics alone versus local anesthetics plus corticosteroids and a placebo for patients with knee OA. A prospective, randomized, double-blind, placebo-controlled trial with 3 parallel groups. Outpatient rehabilitation and orthopedic clinics at a tertiary care hospital. Adults with symptomatic knee OA were randomized to receive an ultrasound-guided GNB that used one of the following substances: (1) 0.5% bupivacaine plus 20 mg triamcinolone (BC group), (2) 0.5% bupivacaine alone (B group), or (3) 2.5 mL saline placebo (S group). The primary outcome was pain intensity, measured using the numeric rating scale (NRS) and the ) pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC at 4, 12, and 24 weeks. Secondary outcomes included scores on the WOMAC function and stiffness subscales, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Kujala score, and mood as measured on the Escala de Valoración del Estado de Ánimo (EVEA). A total of 102 patients completed the study (BC: n = 33; B: n = 35; S: n = 34). Both the BC and B groups achieved greater pain reduction than did the placebo group (interaction P = 0.001). At 4 weeks, the mean NRS pain reduction was 2.24 (95% CI: 0.93-3.55) in the BC group, 2.94 (95% CI: 1.67-4.21) in the B group, and 1.29 (95% CI: 0-2.58) in the S group. These effects were maintained at 24 weeks. Scores on the WOMAC pain and function subscales saw significantly greater improvement in the BC and B groups than did the placebo group (interaction P < 0.05). No significant differences were observed in KOOS, Kujala, or mood scores. No serious adverse events occurred. This study was a single-center trial with a modest sample size. Some secondary outcomes may have been too underpowered to detect group differences. GNBs with bupivacaine provide effective and sustained pain relief for knee OA. The addition of corticosteroids did not yield additional benefits, suggesting that the use of local anesthetics alone may be a safer and sufficient option.