Single Adductor-canal-block Versus Peri-articular Infiltration on Outcome After Total Knee Arthroplasty

Single adductor-canal-block is performed before the surgery. A 12Hz linear ultrasound transducer is placed on the medial part of the thigh with the leg slightly externally rotated. The femoral artery was identified in short axis in the adductor canal, underneath the sartorius muscle. After skin disinfection , an 18-gauge needle (B.Braun Medical, Melsungen, Germany) is inserted in-plane from the lateral side of the transducer. The needle tip was placed underneath the sartorius muscle, just lateral to the artery and saphenous nerve, using 2-3 ml of saline to ensure correct placement. 25 ml of 0.35% ropivacaine is slowly injected with repeated aspiration.

The periarticular infiltration of multimodal agents will involve the preparation of a mixture of 100 ml solution. The mixture contains 30ml (300mg) ropivacaine, 0.5ml (5 mg) morphine, 2 ml (50 mg) flurbiprofen and 0.5 ml of 1:1000 epinephrine, and then is diluted with 0.9% normal saline to a total volume of 100ml. 50 ml of mixture will be injected into the anterior, medial and lateral soft tissues after the implantation of the joint prostheses. The remaining 50 ml of mixture will be injected into intraarticular space after the closure of articular capsule.