Total knee arthroplasty (TKA) is one of the most common orthopedic surgical procedure and is associated with severe pain in the immediate postoperative period, thus limiting early recovery.

Postoperative pain management requires multimodal analgesia, combining drugs and injection of a local anesthetic (LA). For optimal pain management, several peripheral nerve blocks should be associated. Thus, a recent study shows that the combination of IPACK, femoral triangle and obturator nerve blocks (ITO blocks) provides an effective pain control after TKA.

The hypothesis of this study is that a quadruple nerve block combining femoral, sciatic, obturator and lateral femoral cutaneous nerve blocks (quadri-block) could improve analgesia after TKA.

The main objective of this monocenter, prospective, randomized, open-label, controlled trial is to assess the effect of quadri-block on morphine consumption after TKA compared to ITO blocks.

In the pre-anaesthesia room, after the implementation of classical monitoring with an oxygen mask and a peripheral venous catheter, all patients will receive an antibioprophylaxis according to SFAR (French Society of Anesthesia & Intensive Care Medecine) recommendations and injection of 10 mg of IV dexamethasone.

The patients will be then randomized in 2 groups:

• ITO group (usual technique): IPACK combined to femoral triangle and obturator nerve blocks
• Quadriblock group (experimental technique): femoral, sciatic, obturator and lateral femoral cutaneous nerve blocks.

An experienced anesthetist will perform ultrasound-guided blocks 30 minutes before surgery with ropivacaine 0.3%, total volume of 70 ml.

In the operating room, general anesthesia will be induced by intravenous ketamine (0.4 mg/kg) and propofol (3 mg/kg). Anesthesia will be maintained with propofol.

Postoperative analgesia protocol :

• Multimodal analgesia will be instituted from the end of the surgery by the administration of paracetamol (1 g) and ketoprofen (100 mg).
• In post-anesthesia care unit (PACU): oxynorm titration if VRS (pain score) >3 according to the centre's usual care.
• In ward: systematic per os analgesia with paracetamol (1 g, 4 times a day) and ibuprofen (400 mg, 3 times a day); oxynorm (10 mg, lockout interval: 4 h) if VRS (pain score) >3.

Inclusion Criteria:

• 18 years and older,
• Primary total knee arthroplasty
• Consent for participation,
• Affiliation to a social security system

Exclusion Criteria:

• Preoperative morphine use
• Chronic pain syndrome
• Contraindication to any drugs used in the protocol (paracetamol, ketoprofen, oxynorm, propofol, ketamine, ropivacaine)
• Valgus > 9°
• Pregnant or breastfeeding women
• Patients under protection of the adults (guardianship, curators or safeguard of justice)