Continuous Versus Single Injection Adductor Canal Blocks for Outpatient Total Knee Arthroplasty

For continuous nerve blocks, the infusion pump that will be used are OnQ pumps (Avanos, Alpharetta, GA) and pre-filled with ropivacaine 0.2% and provided by UCSD's Investigational Drug Services.

An adductor canal single injection nerve block will be performed per standard of care. The adductor canal will be identified by ultrasound in the short-axis view. The distal aspect of the femoral triangle (and beginning of the adductor canal) will be identified distal to the mid-thigh in the ipsilateral limb. Using ultrasound guidance, a standard Tuohy block needle will be advanced through a skin wheal of lidocaine until its tip is in the hypoechoic area immediately distal saphenous nerve adjacent to the femoral artery. Twenty milliliters of ropivacaine 0.5% will be injected in divided doses with repeated negative aspiration.