Psoas Sciatic Blockade Could be a Sole Anaesthetic Technique for Total Knee Arthroplasty

After approval of the ethics committee, department of anaesthesia, Menoufia university and written informed consent, 80 patients undergoing unilateral total knee arthroplasty were randomly allocated into two groups. The first group (40 patients) received continuous psoas compartment block combined with continuous sciatic block (Pso/Sci group) and the second group (40 patients) received combined spinal epidural anaesthesia (CSE group). All patients were between 50 and 65 years old with an American society of anaesthesiologists classification (ASA status) of I to III. Patients' exclusion criteria included contraindication of regional anesthesia, bleeding disorders, localized infection, neurological deficit, substance dependence, and uncooperative patients. Upon arrival to the operative theater patients were attached to the standard monitoring and an intravenous cannula was inserted. All patients received 1 - 2 mg midazolam for sedation before the blocks.

Sciatic nerve blockade:

The block was done under complete aseptic technique. The patient was positioned in the lateral recumbent position with the operative side up and the hips and knees were flexed. The greater trochanter, posterior superior iliac spine and sacral hiatus were palpated and marked. Curvilinear low frequency U/S probe 2-5 MHz, (Sonosite, M-Turbo, Sonosite Inc., USA) was used for scanning. The probe was placed transversely in the middle of the line connecting the greater trochanter and sacral hiatus. The hip joint and the ischial spine were seen as hyperechoic lines in the lateral and medial sides respectively and the sciatic nerve was appeared as a triangular or flattened hyperechoic structure under the gluteus maximus. Local infiltration with 1 ml lidocaine 2% with 27-gauge needle was done before introducing the 100 mm 18 gauge sterile insulating pajunk needle (PAJUNK, PlexoLong, Germany) for the block.

The pajunk needle was connected to a nerve stimulator (Plexygon, Vygon Italia, Padua, Italy) with 0.8 mA initial current and inserted out of plane reaching the sciatic nerve until eliciting either planter flexion or dorsiflexion with reduced current output up to 0.2 mA. A mixture of 15 ml lidocaine 1% and 15 ml bupivacaine 0.25% were injected around the sciatic nerve. A multi-perforated reinforced catheter was inserted through the needle and advanced 5 cm distal to the needle tip to provide continuous infusion. The needle was removed and the catheter was fixed to the skin.

Psoas compartment blockade: