Comparison of a four-nerve block protocol versus adductor canal block plus local infiltration analgesia for primary total knee arthroplasty in two French private hospitals: protocol for the multicentre randomised INCA trial

Background INCA is a multicentre, prospective, randomised, two-arm superiority trial. 100 adult patients scheduled for primary total knee arthroplasty (TKA) will be randomised 1:1 to one of two locoregional analgesia strategies: group 1 (standard strategy), single-shot adductor canal block (ACB) combined with active surgeon-administered peri-articular infiltration with ropivacaine and participant-facing sham peripheral nerve blocks; group 2 (four-nerve block strategy), single-shot ACB combined with three additional ultrasound-guided nerve blocks (lateral femoral cutaneous, obturator and infiltration between the popliteal artery and capsule of the knee (IPACK) blocks) plus sham surgical infiltration. All patients will receive general anaesthesia and identical systemic multimodal analgesia (paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs), nefopam and rescue opioids) so that any between-group differences can be attributed to the allocated regional strategy. The primary outcome is global recovery at 24 hours, assessed by the Quality of Recovery-15 (QoR-15) questionnaire. Secondary outcomes include postoperative pain scores, opioid consumption, rescue analgesia including any rescue infiltration, motor function and adverse events, range of motion of the index knee, time to first ambulation, postanaesthesia care unit (PACU) stay, hospital length of stay, QoR-15 at 48 hours and Knee Injury and Osteoarthritis Outcome Score-Joint Replacement (KOOS-JR) at 1 month. Methods INCA is a multicentre, prospective, randomised two-arm superiority trial. 100 adult patients scheduled for primary TKA will be randomised 1:1 to one of two locoregional analgesia strategies: group 1 (standard strategy), single-shot ACB combined with surgeon-administered peri-articular infiltration; group 2 (four-nerve block strategy), single-shot ACB combined with three additional ultrasound-guided nerve blocks (lateral femoral cutaneous, obturator and IPACK blocks) without active infiltration. Participant-facing sham procedures will be used to preserve blinding. All patients will receive general anaesthesia and identical systemic multimodal analgesia (paracetamol, NSAIDs, nefopam and rescue opioids) so that any between-group differences can be attributed to the regional strategy. The primary outcome is global recovery at 24 hours, assessed by the QoR-15 questionnaire. Secondary outcomes include postoperative pain scores, opioid consumption, rescue analgesia including any rescue infiltration, motor function and adverse events, range of motion of the index knee, time to first ambulation, PACU stay, hospital length of stay, QoR-15 at 48 hours and KOOS-JR at 1 month. Ethics and dissemination The study protocol has been approved by the regional ethics committee (Comité de Protection des Personnes). All participants provide written informed consent. The trial will be conducted in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. Study results will be disseminated to participants and submitted for publication in a peer-reviewed journal and presented at national and international conferences to inform best practices in TKA analgesia. Trial registration number NCT06920186 . Version 4.0 (11 February 2025).