Dexamethasone as a lower limb block adjuvant for foot and ankle surgery

Epidural dexamethasone has been used for many years as a treatment for lower back pain and more recently for postoperative analgesia. Favourable results have also been demonstrated when dexamethasone is added to bupivacaine for interscalene nerve block: the time to first onset of operative site pain increased from 12 to 20 hours. However, perineural dexamethasone has not been studied when added to bupivacaine for lower limb peripheral nerve block. The main limitation of the lower limb block for postoperative analgesia is its limited duration of effect; therefore, any therapeutic intervention effective in prolonging lower limb block duration has clinical value. The primary aim of this study therefore is to test the hypothesis that the addition of dexamethasone 8 mg to 30 mL bupivacaine 0.5% administered via lower limb block will prolong the time to first pain after foot and ankle surgery conducted under general anaesthesia.