Background and Aims:
Ultrasound guided Adductor Canal Block (ACB) is an effective regional anesthesia technique that is often used as part of multimodal analgesia in knee surgeons. In this study, we aimed to determine ACB activity with bupivacaine in two different concentrations by comparing the control group and the block groups.Methods:
This prospective, randomized, controlled, double-blinded study included three groups (ACB-0.25, ACB-0.16, and control) with 20 patients each (ASA 1-2, aged >18 years due to undergo arthroscopic knee surgery.) All patients underwent the same general anesthesia regimen. All blocks were performed pre-operatively under sedo-analgesia with the application of 15ml of local anesthetic (0.25 % and 0.16% respectively) in experimental groups. In cotrol group, no block was performed. Pain intensity (NRS), PCA tramadol consumption and rescue analgesic requirements were noted for the first 24 hours.

Results
There was no difference between demographic data or type of surgery. While there was no difference in NRS score at any hour between the block groups, tramadol consumption during the first 12 hours  tramadol consumption were statistically significantly higher in the control group compared to both block groups. The rescue analgesic requirement was similar in all groups.

Conclusions:
While ACB performed with concentrations of 0.25% and 0.16% bupivacaine in the same volume have the similar effect, they improve analgesia quality in patients undergoing arthroscopic knee surgery when compared to a control group.

EVALUATION OF ULTRASOUND-GUIDED ADDUCTOR CANAL BLOCK WITH TWO DIFFERENT CONCENTRATION OF BUPIVACAINE  IN ARTHROSCOPIC KNEE SURGERY, CONTROLLED RANDOMIZED PROSPECTIVE STUDY