Selective Tibial Nerve Block vs Local Infiltration Analgesia After Prothetic Knee Surgery

• Total morphine consumption (mg)[ Time Frame: 2 hours, 48 hours and 72 hours postoperatively ]
• Analgesic duration (minutes)[ Time Frame: Postoperative day 0 ]
  Time from the block to the first analgesic request
• Pain scores (numeric rating scale, 0-10) at rest and on movement[ Time Frame: 2 hours, 24 hours, 48 hours and 72 hours postoperatively ]
  0= no pain, 10=the worst pain imaginable
• Rate of postoperative nausea and vomiting[ Time Frame: 2 hours, 24 hours, 48 hours and 72 hours postoperatively ]
  Yes/No
• Rate of prurit[ Time Frame: 2 hours, 24 hours, 48 hours and 72 hours postoperatively ]
  Yes/No
• Active flexion[ Time Frame: 24hours, 48hours and 72hours postoperatively ]
  Flexion of the knee by the patient measured in degrees
• Passive flexion[ Time Frame: 24hours, 48hours and 72hours postoperatively ]
  Flexion of the knee by physiotherapist measured in degrees
• Quadriceps muscle strength (numeric scale, 1-5)[ Time Frame: 24hours, 48hours and 72hours postoperatively ]
  1=no contraction, 5=normal strength
• Distance walked (meters)[ Time Frame: 24hours, 48hours and 72hours postoperatively ]
• Complication of the femoral or tibial nerve block[ Time Frame: up to 1 week ]
  Intravascular injection/hematoma/infection/Common peroneal nerve block
• Length of stay in hospital[ Time Frame: up to 14 days ]
  Days

Patient suffer from moderate posterior knee pain after TKA despite injection of local anesthetic around the femoral nerve (femoral nerve block). Indeed, the posterior part of the knee is innervated by the sciatic nerve. This nerve is not routinely blocked as clinicians fear to produce a motor block of the leg that might impair the postoperative assessment. An analgesic alternative is the infiltration of the knee with local anesthetics performed by the surgeon. Recently a trial(1) demonstrated that a selective tibial nerve block provides an effective analgesia without a motor blockage when compared with a sciatic nerve block. The objective of this randomized controlled double-blinded trial is to assess whether a tibial nerve block is more effective for the postoperative pain than local infiltration analgesia when there are combined with a femoral nerve block, without decreasing the functional parameters.

• Drug: Ropivacaine 0.5% Injectable Solution
  Tibial nerve block with 10ml of Ropivacaine 0.5%
• Drug: Ropivacaine 0.2% Injectable Solution
  Infiltration with 25ml of Ropivacaine 0.2% in the posterior knee capsule

• Experimental: Tibial nerve block
  Femoral nerve and tibial nerve blocks performed by the anesthetist under ultrasound guidance before spinal block.
• Active Comparator: Local infiltration analgesia
  Femoral nerve block by the anesthetist under ultrasound guidance before spinal block. Infiltration of the knee by the surgeon with local anesthetic at the end of the surgery.