Popliteal Nerve Block for Achilles Tendon Repair Surgery

Popliteal sciatic nerve blocks will be performed with the patient in prone position, with the popliteal fossa of the surgical leg marked and sterilized. A high-frequency 10-12 MHz linear array ultrasound transducer will be positioned transversely at the level of the popliteal crease and moved proximally to identify the bifurcation of the sciatic nerve into the tibial and common peroneal nerves. Under ultrasound guidance, a 22-gauge, 80-mm echogenic needle will be inserted using an in-plane lateral-to-medial approach. 15 mL of 0.5% ropivacaine with 2.5 µg/ml of epinephrine will be deposited between tibial and common peroneal nerves within the paraneural sheath. Adequate spread of local anesthetic will be confirmed by visualization of paraneural spread.

Sham blocks will be performed using a 25G needle to inject 1 mL of saline subcutaneously in the popliteus of the surgical knee. Sterilization and ultrasound scanning will mirror that of a popliteal nerve block. The ultrasound screen will be blinded from the patient's vision for all patients in the trial to prevent unblinding by patients with knowledge of the technique.