The purpose of this research is to determine if both local anesthetics (mepivacaine and bupivacaine) are similar in their onset of sensory block to assess the efficiency of ultrasound-guided ankle blocks in our practice. Currently it is the standard of care to perform ankles blocks with both mepivacaine and bupivacaine. However, given similarity in their safety profile researchers would like to compare if one is non-inferior to the other in terms of onset time of ankle block.

Inclusion Criteria:

• Age greater than or equal to 18 years old.
• Patients who provide informed consent to participate.
• Patients undergoing foot surgery who require a peripheral nerve block of the ankle as primary anesthesia.
• ASA (American Society of Anesthesiology) Physical Status Classification I - III.

Exclusion Criteria:

• Inability to consent.
• Allergy to local anesthetic.
• Infection at site of injection.
• Pregnancy.
• Coagulopathy.
• Hepatic or renal failure.
• Preexisting neuropathy in operative limb.
• Planned spinal anesthetic or general anesthesia.

Participants, the anesthesiologist performing the block and assessing the block efficacy over time will all be masked as to which local anesthetic is being used