Knee replacement pain relief: which catheter placement stays put?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Non-pregnant patients older than 18 years of age; * Patients undergoing unilateral primary total knee arthroplasty in an inpatient regime; * American Society of Anesthesiologist (ASA) physical status Class I - IV patients; * With sufficient understanding and co-operation about usage of a perineural catheter for pain management; * With body mass index (BMI) under 45; * With no history of strong opioid use of more than 30 mg of oral morphine equivalent (OME)/day during the 2 weeks preceding the surgery; * No alcohol or drug use disorder history; * With no contra-indication for the performance of ACB and IPACK block; * With no contra-indication for spinal anesthesia; * With no contra-indication for CACB catheter insertion (local site infection, systemic infection, anatomical abnormality); * With no contra-indication for the medications to be used accordingly with the study protocol (ropivacaine, lidocaine, mepivacaine, midazolam, fentanyl, propofol, cefazolin, tranexamic acid, dexamethasone, ondansetron, celecoxib, acetaminophen, hydromorphone); * Speak and understand the English language; * Agree to participate on this study through the signature of the consent form. Exclusion Criteria: * They have a failed spinal anesthesia and needs for a conversion to general anesthesia; * The peripheral nerve blocks are not possible to be performed due to technical difficulties; * A deviation of the protocol occurs (not follow the standardized postoperative analgesia orders; need an emergency re-operation of the same knee, in less than 24 hours, due to a surgical complication; have an important perioperative complication, leading to abnormal level of conscience); * CACB catheter has issues on its function and needs to be removed before the migration assessment * Patient decides to withdraw from the study.