The five-in-two (FIT) ankle block for outpatient foot surgery: a proof-of-concept anatomical and observational study
Lucas Deffontis, Matthias Herteleer, Corentin Roger, Olivier Choquet, Mathieu Capdevila, Wayan Hebrard, Anne Gourari, Aurélien Bonnal, Sophie Bringuier, Xavier CapdevilaIntroduction
Regional anesthesia for foot surgery commonly relies on a five-injection ankle block, a technique associated with technical complexity and patient discomfort. We developed an ultrasound-guided five-in-two (FIT) ankle block based on an anatomical rationale, to provide complete foot anesthesia with only two punctures.
Methods
A dual-injection ankle block technique was defined through an anatomical study, consisting of a mid-calf injection targeting the superficial and deep fibular nerves and a distal transverse injection 5 cm above the medial malleolus targeting the tibial, saphenous, and sural nerves. The technique was assessed in a bicentric prospective observational study of adult patients undergoing outpatient foot surgery, with surgical anesthesia as the primary outcome. Secondary outcomes assessed block performance, perioperative pain intensity, 24-hour rescue analgesic consumption, patient-reported experience, and block-related safety.
Results
80 patients received a FIT ankle block, with successful surgical anesthesia achieved in 77 cases (96%). Median sensory and motor block durations were 554 (420–758) and 600 (444–882) minutes, respectively. Pain was minimal, with median Visual Analogue Scale scores of 0 (0–7) during block placement and 0 (0–4) on arrival in the post-anesthesia care unit. Intravenous rescue analgesia was required in 5% of patients. The median Echelle du Vécu de l’Anesthésie LocoRégionale global score was 88 (80–97), and the complication rate was 0% (95% CI 0 to 3.75%).
Conclusions
The anatomically guided FIT ankle block is an effective proximal motor-sparing regional anesthesia technique for outpatient foot surgery, providing reliable anesthesia, excellent analgesia, and well-tolerated perioperative outcomes.