The Impact of Regional Motor-sparing Blocks on Early Rehabilitation Following Primary Hip or Knee Arthroplasty

The purpose of this study is to determine whether a single nerve block given before surgery can help patients regain independence and mobility more quickly after planned hip or knee replacement surgery for osteoarthritis. Patients undergoing hip replacement will receive a PENG block, while patients undergoing knee replacement will receive an adductor canal block (ACB). Both procedures will be performed using ultrasound guidance. Some patients will receive a control procedure instead of the active nerve block. All participants will receive standard pain treatment and postoperative rehabilitation. The main aim of the study is to compare patients' functional independence approximately 24 hours after surgery. Other outcomes will include the ability to walk independently, performance during physiotherapy, muscle strength, pain intensity, opioid use, adverse events, and readiness for hospital discharge. Participants will be followed from the preoperative visit until 90 days after surgery. The results of this study may help determine whether these nerve blocks are a safe and effective way to support early recovery and restoration of mobility after hip or knee replacement surgery.

Inclusion Criteria * Scheduled for elective primary unilateral total hip arthroplasty (THA) or total knee arthroplasty (TKA) due to osteoarthritis. * Planned spinal anesthesia according to the study protocol. * Ability to walk at least 10 meters before surgery, with or without an assistive device. * Ability to understand and follow the instructions for the mILOA/mILAS and Timed Up and Go (TUG) assessments. * Provision of written informed consent. Exclusion Criteria * Revision arthroplasty, simultaneous bilateral arthroplasty, or arthroplasty performed due to fracture, tumor, or infection. * Contraindication to the study nerve block, ropivacaine, spinal anesthesia, or any mandatory component of the analgesic regimen. * Coagulopathy or anticoagulant therapy incompatible with current recommendations for peripheral nerve blocks or neuraxial anesthesia. * Infection at the planned needle insertion site. * Significant preoperative neurological deficit of the operated limb that would preclude reliable assessment of mobility. * Opioid use disorder or chronic opioid use of ≥30 mg oral morphine equivalent per day for more than 3 months. * Participation in another interventional clinical trial that could affect postoperative rehabilitation. * Inability to ensure assessment of the primary endpoint within the required time window.