Ankle Block vs Single-Shot Popliteal Fossa Block as Primary Anesthesia for Forefoot Operative Procedures: Prospective, Randomized Comparison.

BACKGROUND: Postoperative pain is often difficult to control with oral medications, requiring large doses of opioid analgesia. Regional anesthesia may be used for primary anesthesia, reducing the need for general anesthetic and postoperative pain medication requirements in the immediate postoperative period. The purpose of this study was to compare the analgesic effects of an ankle block (AB) to a single-shot popliteal fossa block (PFB) for patients undergoing orthopedic forefoot procedures.

METHODS: All patients having elective outpatient orthopedic forefoot procedures were invited to participate in the study. Patients were prospectively randomized to receive either an ultrasound-guided AB or PFB by a board-certified anesthesiologist prior to their procedure. Intraoperative conversion to general anesthesia and postanesthesia care unit (PACU) opioid requirements were recorded. Postoperative pain was assessed using the visual analog scale (VAS) at regular time intervals until 8 am on postoperative day (POD) 2. Patients rated the effectiveness of the block on a 1 to 5 scale, with 5 being very effective. A total of 167 patients participated in the study with 88 patients (53%) receiving an AB and 79 (47%) receiving a single-shot PFB.

RESULTS: There was no significant difference in the rate of conversion to general anesthesia between the 2 groups (13.6% [12/88] AB vs 12.7% [10/79] PFB). PACU morphine requirements and doses were significantly reduced in the PFB group ( P = .004) when compared to the AB group. The VAS was also significantly lower for the PFB patients at 10 pm on POD 0 (4.6 vs 1.6, P < .001), 8 am on POD 1 (5.9 vs 4.2, P = .003), and 12 pm on POD 1 (5.4 vs 4.1, P = .01). Overall complication rates were similar between the groups (AB 9% vs PFB 10.1%, P = .51) and there were no significant differences in residual sensory paresthesias (AB 2.3% [2/88] vs PFB 5.1% [4/79], P = .29), motor loss (0% vs 0%), or block site pain and/or erythema (AB 6.9% [6/88] vs PFB 5.1% [4/79], P = .44). The analgesic effect of the PFB lasted significantly longer when compared to the ankle block (AB 14.5 hours vs PFB 20.9 hours, P < .001). There was no significant difference in patient-perceived effectiveness of the block between the 2 groups, with both blocks being highly effective (AB 4.79/5 vs PFB 4.82/5, P = .68).

CONCLUSION: Regional anesthesia was a safe and reliable adjunct to perioperative pain management and highly effective in patients undergoing elective orthopedic forefoot procedures. However, patients who received a PFB had significantly better pain management and decreased opioid requirements in the immediate perioperative period than patients who received an ankle block.

LEVEL OF EVIDENCE: Level I, prospective randomized study.