Effective postoperative pain management remains a cornerstone of enhanced recovery protocols following total knee arthroplasty (TKA). Inadequate analgesia not only compromises patient satisfaction but also impedes early mobilization and rehabilitation, thereby increasing the risk of perioperative complications. Current multimodal analgesic strategies frequently incorporate regional techniques, with the adductor canal block (ACB) and infiltration between the popliteal artery and capsule of the knee (IPACK) block emerging as established modalities that provide motor-sparing analgesia.
Despite their widespread adoption, the optimal local anesthetic regimen for these blocks remains undefined. While liposomal bupivacaine has garnered interest for its extended duration of action, its clinical efficacy relative to conventional local anesthetics combined with perineural adjuncts remains a subject of ongoing debate. Specifically, perineural dexamethasone and dexmedetomidine have each demonstrated the capacity to prolong the analgesic duration of ropivacaine; however, direct comparative data among these three distinct strategies-liposomal bupivacaine alone versus ropivacaine supplemented with either adjunct-are notably limited.
Given the absence of head-to-head randomized trials evaluating these three clinically viable techniques, the optimal approach to maximize analgesic duration while minimizing opioid-related adverse effects remains unclear. This study therefore aims to compare the analgesic efficacy and safety profiles of liposomal bupivacaine, ropivacaine with perineural dexamethasone, and ropivacaine with perineural dexmedetomidine when administered via ACB and IPACK blocks in patients undergoing TKA.
Patients scheduled for elective primary unilateral total knee arthroplasty
Age ≥ 18 years and ≤ 80 years
American Society of Anesthesiologists (ASA) physical status I-III
Body mass index (BMI) ≥ 18 kg/m² and ≤ 35 kg/m²
Known allergy or contraindication to local anesthetics (bupivacaine, ropivacaine), dexamethasone, dexmedetomidine, or opioids
Infection at the injection site
Coagulopathy or current use of anticoagulants
Severe cardiovascular disease (New York Heart Association [NYHA] functional class III or IV, or recent myocardial infarction within 6 months)
Parallel
Liposomal bupivacaine (LB)
DrugLiposomal bupivacaine 6.65% injection. A total volume of 40 mL will be administered as ultrasound-guided adductor canal block (ACB) and infiltration between the popliteal artery and capsule of the knee (IPACK) block, divided as 20 mL for each block, prior to surgical incision.
Ropivacaine with Perineural Dexamethasone
DrugRopivacaine 0.375% combined with dexamethasone 4 mg per block (total 8 mg) as a perineural adjunct. A total volume of 40 mL will be administered as ultrasound-guided adductor canal block (ACB) and infiltration between the popliteal artery and capsule of the knee (IPACK) block, divided as 20 mL for each block
Ropivacaine with Perineural Dexmedetomidine
DrugRopivacaine 0.375% with dexmedetomidine 1 μg/kg (actual body weight). Total 40 mL (20 mL per block) via ultrasound-guided ACB and IPACK
Total opioid consumption
Total postoperative opioid consumption within 72 hour after surgery.
Pain scores at rest and during movement
Visual Analog Scale (VAS, 0-100 mm) within 72 hour postoperatively.
Time to First Ambulation
Time from arrival in PACU to first ambulation
Duration of Hospital Stay
Time from surgery to hospital discharge, measured in days.
Patient Satisfaction with Pain Management
Patient satisfaction assessed using a 5-point Likert scale (1 = very dissatisfied, 5 = very satisfied).
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