Effectiveness of local infiltration analgesia and femoral nerve block in primary total knee arthroplasty: A prospective, participant and outcome-assessor-blinded randomized trial
Abstract
Postoperative pain following total knee arthroplasty (TKA) can delay mobilization and increase the need for opioids. Local infiltration analgesia (LIA) and femoral nerve block (FNB) are widely used methods in postoperative multimodal analgesia, but the added value of combining these techniques remains uncertain. In this prospective, participant- and outcome-assessor-blinded randomized trial (ISRCTN11696218), 125 patients undergoing primary TKA for idiopathic osteoarthritis (Kellgren–Lawrence grades II–III) were randomized into five groups: (1) Control (no additional intervention), (2) Placebo (periarticular infiltration with 100 mL saline), (3) LIA (periarticular infiltration with ropivacaine 300 mg + epinephrine 1 mg + piroxicam 20 mg diluted with saline to a total volume of 100 mL), (4) FNB (ultrasound-guided, bupivacaine 25–50 mg + epinephrine 25–50 mcg, dosed according to the attending anesthesiologist’s preference, + 100 mL saline infiltration), and (5) LIA + FNB. Outcomes were assessed preoperatively and on postoperative days (POD) 1–5. Primary outcomes included mean opioid consumption converted to morphine milligram equivalents (MME). Secondary outcomes included pain intensity measured by a visual analog scale (VAS), and passive knee range of motion (ROM). Statistically, to exclude the influence of confounding factors in the form of contralateral knee surgery, a longitudinal linear mixed-effects model was constructed. A total of 125 patients were randomized and analyzed. Baseline demographics were comparable across groups. On POD 1, the LIA + FNB group had lower mean opioid requirements (93.7 mg MME) compared to the Placebo group (138.6 mg MME; mean difference − 44.9 mg MME), the isolated FNB group ( 123.7 mg MME; mean difference − 30.0 mg MME), and the isolated LIA group (116.8 mg MME; mean difference − 23.2 mg MME, p=0.027 ), but there was no difference compared to the Control group (107.4 mg MME) Opioid use dropped sharply after POD 1 and remained relatively low across all groups from POD 2 to POD 5, with minor fluctuations. Early postoperative pain scores remained moderately high (mean VAS 5.5–6.9) on POD 1 across all interventions. The LIA+FNB group demonstrated an early ROM advantage on POD 1 (mean 66.7°); however, from POD 3 onward, LIA alone provided comparable mobility benefits (POD 5 mean 97.6°). Combining LIA and FNB provides a modest, time-limited reduction in early opioid consumption on POD 1 compared to a placebo infiltration or isolated FNB but lacks overall superiority over a standard control or LIA administered alone. LIA utilized as an independent strategy optimizes mobility recovery without the added interventions of peripheral blocks. The addition of FNB to LIA does not substantially alter the overall recovery trajectory.
Trial registry : ISRCTN11696218 https://www.isrctn.com/ISRCTN11696218 (retrospectively registered on November 25, 2025).
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BibTeX
@article{kocon2026effectiveness,
title = {{Effectiveness of local infiltration analgesia and femoral nerve block in primary total knee arthroplasty: A prospective, participant and outcome-assessor-blinded randomized trial}},
author = {Maciej Kocon and Magdalena Fleming and Dariusz Grzelecki},
journal = {Scientific Reports},
year = {2026},
month = oct,
doi = {10.1038/s41598-026-75203-x},
url = {https://www.nature.com/articles/s41598-026-75203-x},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Effectiveness of local infiltration analgesia and femoral nerve block in primary total knee arthroplasty: A prospective, participant and outcome-assessor-blinded randomized trial
AU - Maciej Kocon
AU - Magdalena Fleming
AU - Dariusz Grzelecki
PY - 2026
DA - 2026/10/17
JO - Scientific Reports
DO - 10.1038/s41598-026-75203-x
UR - https://www.nature.com/articles/s41598-026-75203-x
AB - Postoperative pain following total knee arthroplasty (TKA) can delay mobilization and increase the need for opioids. Local infiltration analgesia (LIA) and femoral nerve block (FNB) are widely used methods in postoperative multimodal analgesia, but the added value of combining these techniques remains uncertain. In this prospective, participant- and outcome-assessor-blinded randomized trial (ISRCTN11696218), 125 patients undergoing primary TKA for idiopathic osteoarthritis (Kellgren–Lawrence grades II–III) were randomized into five groups: (1) Control (no additional intervention), (2) Placebo (periarticular infiltration with 100 mL saline), (3) LIA (periarticular infiltration with ropivacaine 300 mg + epinephrine 1 mg + piroxicam 20 mg diluted with saline to a total volume of 100 mL), (4) FNB (ultrasound-guided, bupivacaine 25–50 mg + epinephrine 25–50 mcg, dosed according to the attending anesthesiologist’s preference, + 100 mL saline infiltration), and (5) LIA + FNB. Outcomes were assessed preoperatively and on postoperative days (POD) 1–5. Primary outcomes included mean opioid consumption converted to morphine milligram equivalents (MME). Secondary outcomes included pain intensity measured by a visual analog scale (VAS), and passive knee range of motion (ROM). Statistically, to exclude the influence of confounding factors in the form of contralateral knee surgery, a longitudinal linear mixed-effects model was constructed. A total of 125 patients were randomized and analyzed. Baseline demographics were comparable across groups. On POD 1, the LIA + FNB group had lower mean opioid requirements (93.7 mg MME) compared to the Placebo group (138.6 mg MME; mean difference − 44.9 mg MME), the isolated FNB group ( 123.7 mg MME; mean difference − 30.0 mg MME), and the isolated LIA group (116.8 mg MME; mean difference − 23.2 mg MME, p=0.027 ), but there was no difference compared to the Control group (107.4 mg MME) Opioid use dropped sharply after POD 1 and remained relatively low across all groups from POD 2 to POD 5, with minor fluctuations. Early postoperative pain scores remained moderately high (mean VAS 5.5–6.9) on POD 1 across all interventions. The LIA+FNB group demonstrated an early ROM advantage on POD 1 (mean 66.7°); however, from POD 3 onward, LIA alone provided comparable mobility benefits (POD 5 mean 97.6°). Combining LIA and FNB provides a modest, time-limited reduction in early opioid consumption on POD 1 compared to a placebo infiltration or isolated FNB but lacks overall superiority over a standard control or LIA administered alone. LIA utilized as an independent strategy optimizes mobility recovery without the added interventions of peripheral blocks. The addition of FNB to LIA does not substantially alter the overall recovery trajectory. Trial registry : ISRCTN11696218 https://www.isrctn.com/ISRCTN11696218 (retrospectively registered on November 25, 2025).
SN - 2045-2322
ER -