DP32: ULTRASOUND-GUIDED TWO-FOR-FOUR HIGH ANKLE BLOCK: A MOTOR-SPARING TECHNIQUE FOR SELECTIVE ANKLE SURGERY
Alisha Shah, MD; Soleil Schutte, MD; Hadia Masqood; Svetlana Chembrovich; Linda Le-Wendling, MD; Meena Kanhai, MD; Barys Ihnatsenka
University of Florida
Background: Ultrasound-guided ankle block is an established regional anesthetic technique for foot surgery, offering motor-sparing advantages compared with proximal approaches such as popliteal sciatic nerve blocks. However, the traditional ankle block requires up to five separate injections and does not provide coverage of the ankle itself. We describe a modified ultrasound-guided high ankle block (HAB) performed 10–12 cm proximal to the malleoli that enables blockade of four distal nerves using two injection sites, with an optional third injection for sural nerve coverage. We present a brief technical description and a prospective case series evaluating feasibility, sensory-motor effects, and analgesic outcomes.
Methods: After obtaining informed consent, three adult patients undergoing outpatient ankle or hindfoot surgery received ultrasound-guided HAB in the preoperative holding area. Institutional Review Board review was not required for this technique report. Using a high-frequency linear transducer (12–15 MHz), the posterior tibial and saphenous nerves were identified medially and blocked through a single insertion site. Laterally, the superficial and deep peroneal nerves were identified and anesthetized via a second insertion site. The sural nerve was blocked selectively when surgical distribution required it. Ropivacaine 0.5% with dexamethasone (0.13 mg/mL) was administered in divided doses per nerve. We injected 10 mL on the posterior tibial, 5 mL on saphenous, 5 mL on superficial peroneal, and 10 mL on the deep peroneal nerves.Standard monitors and intravenous sedation were used. Sensory and motor function were assessed 20–30 minutes post-block. Postoperative pain scores, analgesic requirements, and block duration were recorded.
Results: All three patients achieved complete sensory blockade to ice of the foot and ankle within 30 minutes. Gross ankle plantarflexion and dorsiflexion were preserved bilaterally, consistent with motor-sparing characteristics. Toe motor strength varied from complete weakness (0/5) in one patient to partial weakness (3–4/5) in two patients. All patients underwent general anesthesia without complications. Two patients undergoing less extensive procedures reported complete postoperative analgesia (Numeric Rating Scale [NRS] 0) without opioid requirements; block duration exceeded 20 hours (20 and 26 hours, respectively). The third patient, who underwent combined subtalar and talonavicular fusion, reported moderate pain (NRS 6) localized to the lateral ankle and required postoperative ketorolac and oxycodone. Block duration in this patient was 12 hours. No block-related complications were observed.
Discussion: The ultrasound-guided HAB provides a streamlined alternative to the traditional five-injection ankle block while extending coverage to the ankle joint. By combining nerve targets at proximal locations, this “two-for-four” approach reduces needle insertions and may improve patient comfort without sacrificing analgesic efficacy. Preservation of ankle motor function may decrease fall risk and risk of permanent motor deficits compared with proximal saphenous/popliteal sciatic blockade while maintaining excellent postoperative analgesia for select procedures. Although limited by small sample size, this case series demonstrates feasibility, effective sensory blockade, and prolonged analgesia with minimal motor impairment. Larger comparative studies are warranted to further define indications, efficacy across diverse ankle surgeries, and potential advantages over conventional distal ankle or popliteal approaches.