Ultrasound guided adductor canal block (ACB) was first reported in 2009 by anesthesiologists at the University of Utah. This block is unique in that it spares motor function in the lower extremity. Since 2009, a number of publications have described the successful use of ACB for pain management after total knee arthroplasty (TKA), anterior cruciate ligament (ACL) reconstruction, and other procedures of the knee. As a component of multi-modal analgesia, ACB can provide effective postoperative pain control and facilitate early hospital discharge.