Ultrasound-guided versus anatomic landmark-guided ankle blocks: a 6-year retrospective review

Ultrasound-guided (USG) ankle block has been described; however, its clinical efficacy compared with conventional anatomic landmark-guided (ALG) techniques remains undetermined.

We performed a 6-year retrospective cohort study of all ankle blocks performed for foot surgery and extracted demographic, intraoperative, and postoperative outcome data. We divided blocks into 2 groups for comparison, depending on whether they were performed using an ALG technique or a USG technique.

We identified 655 patients who received unilateral ankle block and 58 patients who received bilateral ankle block; we analyzed these separately. Trainees performed most blocks (approximately 80%). In patients receiving unilateral ankle block, successful surgical anesthesia was more likely in the USG group (84% versus 66%, P < 0.001). Patients in the ALG group were more likely to require supplemental local anesthesia (10% versus 5%, P = 0.04), unplanned general anesthesia (17% versus 7%, P = 0.001), or supplemental fentanyl (18% versus 9%, P = 0.002). Postanesthetic care unit pain scores were similar between groups. However, patients in the ALG group were more likely to receive intravenous opioids (21% versus 12%, P = 0.01), and they received a higher mean opioid dose (10.6 versus 8.7 mg intravenous morphine, ALG versus USG, P = 0.022). In patients receiving bilateral ankle block, successful surgical anesthesia was also more likely in the USG group (84% versus 57%); however, this was not statistically significant because of the small sample size.

This study demonstrates that the USG technique of ankle block improves clinical efficacy compared with a conventional ALG technique, particularly in the hands of less-experienced practitioners.