Intraoperative surgical versus preoperative ultrasound‑guided adductor canal block for analgesia after total knee arthroplasty: A randomized trial

Adductor canal block (ACB) offers opioid-sparing analgesia after total knee arthroplasty (TKA), with limited quadriceps weakness. A practical alternative is a surgeon‑performed intraoperative ACB. This study aimed to evaluate: (Q1) Does surgical ACB (S-ACB) reduce pain at rest 24 h after TKA versus anesthesiologist‑performed ultrasound‑guided ACB (US‑ACB)? , (Q2) Does S-ACB reduce 24‑h opioid consumption? , (Q3) Are there differences in early pain, rescue blocks, or adverse events? , (Q4) Does S-ACB impact length of stay (LOS)? We hypothesized that S-ACB would be superior to US-ACB in reducing rest pain at 24 hours after TKA. Single-center, randomized, open-label trial of adults undergoing unilateral primary TKA (January 2025 - June 2025). Patients were randomized 1:1 to S‑ACB (intraoperative injection into the adductor canal using predefined anatomical landmarks) or US‑ACB (preoperative in‑plane injection adjacent to the femoral artery, beneath vastus medialis). Both groups received 15 mL ropivacaine 0.475% for ACB and 40 mL ropivacaine 0.2% posterior capsular infiltration. The primary outcome was NRS pain at rest 24 h. Secondary outcomes: included 24-h morphine consumption, NRS in post-anesthesia care unit (PACU), at post-operative day 3 (POD3), last in-hospital, rescue block, adverse events, and length of hospital stay (LOS). Intention‑to‑treat analyses were performed. Fifty‑one TKAs were analyzed (S‑ACB n = 27; US‑ACB n = 24). Baseline characteristics were balanced except for diabetes (more frequent in US-ACB). Primary outcome: mean 24‑h NRS was 1.6 ± 1.8 (S‑ACB) vs 2.0 ± 2.2 (US‑ACB); mean difference -0.33 (S‑ACB–US‑ACB), 95% CI –1.44 to 0.78; not statistically significant. 24‑h morphine: 5.6 ± 4.0 mg (S‑ACB) vs 5.8 ± 3.7 mg (US‑ACB); difference -0.16 mg, 95% CI −2.67 to 2.37 mg; not significant. No block‑related adverse events occurred. Rates of rescue block were low (two in US‑ACB). LOS was similar (6.5 ± 3.1 vs 6.7 ± 2.4 nights). Across timepoints (PACU, POD3, discharge), NRS and opioid use did not differ. Surgical ACB did not provide superior analgesia compared to US-ACB at 24 h, with low pain scores and opioid needs overall and no safety issue. Larger multicenter trials are warranted to confirm equivalence and explore functional recovery. II; Randomized trial.