Liposomal Bupivacaine versus Bupivacaine Hydrochloride Plus Dexamethasone for Combined Adductor Canal and iPACK Blocks in Total Knee Arthroplasty: A Randomized Controlled Trial.

PURPOSE: To compare postoperative analgesia and early quadriceps recovery between liposomal bupivacaine and bupivacaine hydrochloride plus dexamethasone administered through combined adductor canal block (ACB) and infiltration between the popliteal artery and capsule of the posterior knee (iPACK) in patients undergoing total knee arthroplasty (TKA).

METHODS

This single-center, randomized, controlled, outcome-assessor-blinded trial included 60 patients in the final analysis (30 per group). The BL group received liposomal bupivacaine plus bupivacaine hydrochloride, whereas the Dex group received bupivacaine hydrochloride plus dexamethasone; both regimens were administered through combined ACB and iPACK. The primary outcome was the visual analog scale (VAS) pain score at rest 24 hours after surgery. Secondary outcomes included pain at other time points, intraoperative hemodynamics and opioid use, quadriceps muscle strength, patient-controlled intravenous analgesia (PCIA) consumption, rescue analgesia, and opioid-related adverse events. The trial was registered with the Chinese Clinical Trial Registry (ChiCTR2500115826; December 31, 2025).

RESULTS

At 24 hours, resting VAS scores were 2.4±0.8 in the BL group and 2.9±1.1 in the Dex group, with a mean difference of -0.52 points (95% CI, -1.01 to -0.02; P=0.040). Repeated-measures analysis showed significant group, time, and group-by-time effects for both resting and movement VAS, and quadriceps strength favored the BL group at 12 hours. The 48-hour cumulative PCIA volume was 99.75 (96.00, 100.00) mL versus 100.00 (100.00, 100.00) mL (P<0.001). Rescue analgesia was more frequent in the Dex group overall (RR=2.40, 95% CI 1.12-5.14; P=0.024), including at 48 hours (3/30 vs 11/30; P=0.030).

CONCLUSION

In patients undergoing TKA, the liposomal bupivacaine-containing ACB+iPACK regimen was associated with lower postoperative pain at selected time points and better quadriceps strength at 12 hours than the bupivacaine hydrochloride plus dexamethasone regimen. These findings suggest a potential early analgesic benefit during the first 72 postoperative hours, although the clinical importance of the pain difference warrants cautious interpretation.