Duration of Sciatic Nerve Block After Injection of Local Anesthetic In or Around the Nerve

"The injection will start as the needle penetrates the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as intraneural if nerve cross section expansion and a reduction in echogenicity are observed.~Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach."

"The injection will start as the needle indents the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as intraneural if the drug infiltrates the space between the epimysium of the surrounding muscles and the outer epineurium of the sciatic nerve.~Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach."

Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.

Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.

Thirty milliliters of 1.5% (wt/vol) mepivacaine will be used for the sciatic nerve block.