Comparison between ultrasound-guided SPANK block and IPACK block added to adductor canal block for postoperative analgesia after total knee replacement

Background and aim Total knee arthroplasty (TKA) is associated with significant postoperative pain, where an adductor canal block (ACB) addresses anterior pain but spares the posterior knee, which remains a significant pain source. The infiltration between the popliteal artery and the capsule of the knee (IPACK) and sensory posterior articular nerve of the knee (SPANK) blocks are two motor-sparing techniques to manage this posterior pain. We aimed to compare the analgesic efficacy of ultrasound-guided IPACK block versus SPANK block when combined with ACB after TKA. Patients and methods This prospective, randomized, single-blinded study involved 90 patients undergoing elective unilateral TKA under spinal anesthesia, allocated to receive either ACB+IPACK (group I, n =45) or ACB+SPANK (group S, n =45). The primary outcome was the duration of analgesia. Secondary outcomes included pain scores of visual analog scale (VAS), total opioid consumption, time to first rescue analgesia, hemodynamics, and adverse effects. Results Group I demonstrated a significantly longer duration of analgesia (877.44±115.1 vs. 461.96±78.5 min, P <0.001) and time to first rescue analgesia (14.6±1.66 vs. 8.16±1.55 h, P <0.001). Total 24-h nalbuphine consumption was significantly lower in group I (6.76±2.23 vs. 9.87±2.64 mg, P <0.001), with superior pain scores at 8, 12, and 18 h. Conclusion Combining ACB with the IPACK block provides more effective and prolonged postoperative analgesia than ACB with the SPANK block, reducing opioid requirements and improving pain control without increasing side effects.