Addition of Popliteal Plexus Block to Continuous Femoral Nerve Block for Total Knee Arthroplasty

The popliteal plexus block has been described as an alternative analgesic postoperative pain treatment for total knee arthroplasty. It consists of injecting local anaeshetics inside the distal end of the adductor canal close to the adductor hiatus, adjacent to the femoral artery, between the medial vastus muscle and the adductor magnus muscle, in order to anesthetize the popliteal plexus. However, the analgesic efficacy has never been demonstrated in a randomized controlled trial. Therefore the objective of this study is to investigate the analgesic benefit of this block combined with a continuous femoral nerve block, on patients scheduled for total knee athroplasty.

Patients scheduled to undergo total knee arthroplasty under general anesthesia will be randomly allocated to two groups: continuous femoral nerve block alone or continuous femoral nerve block with addition of a popliteal plexus block. The continuous femoral nerve block will be performed by the anesthesiologist with 15 mLs of ropivacaine 0.5%, under ultrasound guidance before the beginning of the general anesthesia. The popliteal plexus block will be done by the anesthesiology, under ultrasound guidance, before the beginning of the surgery, under general anesthesia. Postoperative analgesia will include acetaminophen (4 x 1000 mg), ibuprofen (3 x 400 mg) and a continuous infusion of Ropivacaine 0.2%.

Continuous femoral nerve block with injection of 15 mls of Ropivacain 0.5% adjacent to the lateral aspect of the femoral nerve below the fascia iliaca and placement of the catheter within the vicinity of the femoral nerve, juste deep to the fascia iliaca

Continuous femoral nerve block with injection of 15 mls of Ropivacain 0.5% adjacent to the lateral aspect of the femoral nerve below the fascia iliaca and placement of the catheter within the vicinity of the femoral nerve, juste deep to the fascia iliaca.

Popliteal plexus block with injection of 15 mls of Ropivacain 0.5% inside the distal end of the adductor canal close to the adductor hiatus, adjacent to the femoral artery, between the medial vastus muscle and the adductor Magnus muscle, done under general anesthesia.

Onset of action = beginning of the disinfection; End of action = end of injection of 15 mls of Ropivacain 0.5%

Onset of action = Time from end of infection of 15 mls of Ropivacain 0.5%; End of action = onset of lateral and/or posterior knee pain (With Numeric rating scale ≥ 4)

Inclusion Criteria: Patients scheduled for total knee athroplasty under general anesthesia ASA 1-3 Exclusion Criteria: Kidney disease with GFR < 50 ml/mn Daily opioid consumption > 1 month Allergy to local anesthetics Neurological problems of the lower extremity other contraindications to peripheral nerve blocks