Anterior nerves of the knee (ANK) block: A novel motor sparing fascial plane block for analgesia of the knee: Observational cohort study

Knee osteoarthritis is a widespread disorder that may contribute to severe chronic pain. Multiple nerve blocks are implemented for analgesia of the knee, which have some restrictions, including the need for multiple injections, making the procedure complicated. We aimed to introduce a novel ultrasound-guided nerve block technique for analgesia of the knee. The study presents a description of the anterior nerves of the knee block and its application to individuals with knee osteoarthritis. Local anesthetic was injected (20 mL of 0.25% bupivacaine) within the fascia between the rectus femoris and vastus muscles in 42 patients with severe knee pain. The pain charts of the patients were reviewed and numerical rating pain scores (NRS) before and 1st hour, 1st month after the block were evaluated. First-month Western Ontario and McMaster Universities Arthritis Index (WOMAC) was also reviewed. The block was also performed in a fresh embalmed cadaver with methylene blue to identify the distribution of the injected dye. The mean age of patients was 65.3 ± 7.8 years. The mean NRS before block performance was 8.0 ± 1.2. The NRS score at 1 hour and 1 month after the block, decreased to 1.5 ± 1 and 4.4 ± 1.2, respectively. The decrease was statistically and clinically significant (P = .000). Mean WOMAC score was 71.6 ± 14.5 before the block which decreased to 42.7 ± 14.9 one month after the block (P = .000). No muscle weakness, motor block, or block-related complications were observed. Methylene blue spread in the cadaver was between the rectus femoris and vastus muscles, covering the nerves that innervate the anterior region of the knee. The novel anterior nerves of the knee block provided sufficient analgesia at the first hour and first month, and improved 1-month WOMAC scores in patients with chronic pain at the anterior of knee.