The Sacral Erector Spinae Plane Block in Total Knee Arthroplasty

The goal of this observational study is to learn about the analgesic efficacy and postoperative recovery of two locoregional anesthesia combinations in patients \> 18 years (ASA I-III), scheduled for unilateral TKA under spinal anesthesia with expected hospitalization \> 24 hours:

* ACB + sacral ESP block * ACB + iPACK block

The main question it aims to answer is: Does the ACB + sacral ESP block combination produce effective postoperative recovery and analgesic effect?

Participants already taking ACB + sacral ESP block as part of their regular peri-operative care for TKA will be followed in the postoperative period for 48 hours.