Regional anaesthesia has become the cornerstone of multimodal analgesia. With the advent of ultrasound guided nerve blocks regional anaesthesia has achieved both greater efficacy and a better safety profile as the injection of local anaesthetic is performed under direct vision. This has allowed a reduction of the amount of local anaesthetic injected as compared to peripheral nerve stimulation technique . Blockade of sciatic nerve combined with saphenous nerve provides anaesthesia and analgesia for ankle/foot surgeries. Various combinations of local anaesthetics have been used to provide optimal blockade . A mixture of lidocaine with a long acting local anaesthetic is commonly used. This provides a rapid onset of blockade, but of a consistently shorter duration compared to a long acting local anaesthetic alone. We hypothesize that sequential perineural injection of lidocaine and bupivacaine provides similar onset but a longer duration of sensory block compared to the same dose and volume of local anaesthetic mixed in advance.

Inclusion Criteria:

• Patients with ASA 1 - 3 status
• scheduled to undergo semi-elective ankle/foot surgery under regional anaesthesia +/- sedation/opioid free general anaesthesia will be recruited

Exclusion Criteria:

• Patients having surgery on the medial aspect of the ankle/ foot
• allergy to local anaesthetics
• coagulopathy
• malignancy or infection in the popliteal area
• significant peripheral neuropathy
• neurologic disorder of the lower extremity
• any other contraindication to sciatic nerve block
• pregnancy
• history of alcohol or drug dependency/abuse (defined as >40 IU/week)
• a history of significant cognitive or psychiatric disorder that may affect patient assessment