Abstract / Summary
Abstract Background We assessed whether a combined regional analgesic regimen administered immediately before passive knee training on postoperative day 3 was associated with active knee range of motion (ROM) 90 days after the intervention. Methods In this two-center, parallel-group, sham-controlled superiority trial, 220 participants were randomized 1:1. The combined-regimen group received an ultrasound-guided femoral nerve block with 20 mL of 0.5% ropivacaine and posterior knee pain-point infiltration with 5 mL of 0.5% ropivacaine (25 mL; 125 mg total). The sham-control group underwent superficial subcutaneous puncture without injection or posterior infiltration. The primary outcome was active knee ROM 90 days after the postoperative-day-3 procedure. The complete-case analysis included 208 participants with available primary-outcome data (104 per group); missing values were not imputed. Results At 90 days, the baseline-adjusted mean difference in active ROM was 9.12° (95% confidence interval [CI], 7.17 to 11.07; P < 0.001). Immediately after the procedure, adjusted between-group differences were 35.75° (95% CI, 33.80 to 37.69) for passive ROM and − 4.02 points (95% CI, -4.31 to -3.73) for movement-related pain. Length of stay was shorter by 2.15 days (95% CI, 1.55 to 2.75). Among 208 participants with complete safety follow-up, adverse events were recorded in 16/104 (15.4%) and 15/104 (14.4%) participants, respectively (risk ratio, 1.07; 95% CI, 0.56 to 2.04). One periprosthetic tibial fracture in a sham-control participant without complete follow-up was reported separately. Conclusions In the complete-case analysis, the combined regimen was associated with greater active ROM at 90 days and with less pain and greater passive ROM during the targeted training session. Because the intervention was delivered as a bundle, the contribution of each component cannot be determined. The study was not designed to establish safety equivalence, and 12 randomized participants lacked primary-outcome data. Trial registration Chinese Clinical Trial Registry, ChiCTR2500099543. Registered on March 25, 2025, before patient enrollment.