The purpose of this study is to compare the analgesic efficacy of the combination of an adductor canal and selective tibial nerve blocks versus adductor canal block and IPACK after ACL reconstruction under general anaesthesia.

The hypothesis of this study is that a combined adductor canal and selective tibial nerve block provides better analgesia than a combined adductor canal block and IPACK in patients undergoing anterior cruciate ligament reconstruction.

This randomized controlled trial will include two groups: an adductor canal block plus IPACK group (group IPACK) and an adductor canal block plus tibial selective nerve block group (group TIBIAL). After written informed consent, patients will be allocated to one of the groups, following a computer-generated list of randomization.

Prior to surgery, all patients will have an adductor canal block with 20ml of ropivacaine 0.75%. In group TIBIAL the patient will receive in addition a selective tibial nerve block with 5 ml of ropivacaine 0.75%. In group IPACK the patient will receive in addition an IPACK with 20ml of ropivacaine 0.2%. In both groups, patients will have the surgery under general anaesthesia with a multimodal analgesic regimen inclusive of iv dexamethasone 8 mg, iv magnesium sulfate 40 mg.kg-1, iv ketorolac 30 mg, and iv acetaminophen 1000 mg.

After surgery, all patients will be prescribed an iv patient-controlled analgesia (PCA) of morphine (boluses of 2 mg available every 10 min, maximum of 40 mg every 4 hours) along with oral acetaminophen (1000 mg every 6 h) and oral ibuprofen (400 mg every 8 hours). Oral ondansetron 4 mg every 8 hours will be available on request in case of nausea or vomiting.

The primary outcome will be the cumulative iv morphine consumption at 24 h postoperatively. Secondary outcomes will include pain- and functional-related outcomes. Pain-related outcomes include cumulative morphine consumption at 2h and 48h postoperatively, rest and dynamic pain scores and rate of PONV at 2 h, 24 h and 48 h postoperatively. Early functional-related outcomes include range of motion, strength and walking distance at 24 h and 48 h postoperatively. Late functional-related outcomes include range of motion, strength, hop distance, agility test, Y balance test, Anterior Cruciate Ligament Return to Sport After Injury Scale (ACL-RSI) and International Knee Documentation Committee Scale (IKDC) at 4 and 8 months postoperatively.

Inclusion Criteria:

• ASA score I-III
• 18 years or older
• Scheduled for elective primary ACL reconstruction
• Signature of consent form

Exclusion Criteria:

• Refusal or inability for informed consent
• Known allergies to ropivacaine, acetaminophen, ibuprofen, ketorolac, morphine, sufentanyl, ondansetron or dexamethason
• Secondary surgical revision
• Opioid treatment such as morphine, hydrocodone, hydromorphone, tramadol, methadone, fentanyl, buprenorphine or codeine
• Bleeding diathesis
• Neurological deficit
• Known renal insufficiency (eGFR <45 ml/min)
• Known hepatic insufficiency (Child score B or C)
• Pregnancy or lactating
• Alcohol abuse