Revision total knee arthroplasty (rTKA) is a frequently performed procedure. Adequate pain management is an important feature, especially for fast-track and Enhanced Recovery After Surgery (ERAS) programs. The multimodal approach, including single shot or continuous nerve blocks with catheters and spinal or epidural morphine, is a stablished strategy. Although the administration of intrathecal morphine (IM) has been shown to significantly reduce pain scores, it is not free of adverse effects. Postoperative urinary retention (POUR) is possible and might increase the risk of periprosthetic infection. The purpose of this study is to compare patients undergoing rTKAS under spinal anesthesia with IM to patients undergoing the same procedure, under the same anesthetic technique, but with no IM, for POUR and postoperative pain related outcomes. All patients will have single shot and continuous adductor canal block (CACB) and single shot IPACK (interspace between the popliteal artery and the posterior knee capsule) block. The hypothesis is that postoperative pain control is comparable between the groups, with lower incidence of POUR in patients with no IM given.
Non pregnant patients undergoing unilateral non infected rTKA surgery;
Older than 21 years of age, with American Society of Anesthesiologists (ASA) physical status I-III;
With no alcohol or drug dependency history;
With sufficient understanding and co-operation about the usage of a perineural catheter for pain management; body mass index (BMI) under 45;
Patients will be excluded of the study if they have a failed spinal anesthesia and needs for a conversion to general anesthesia;
If peripheral nerve blocks are not possible to be performed due to technical difficulties;
If during patient's care a deviation of the protocol occurs;
If CACB catheter has issues on its function, disconnects or exteriorizes within the first 48 hours of infusion;