[Posterior block of lumbar plexus for postoperative analgesia after hip arthroplasty]

To describe early postoperative analgesic quality from a posterior lumbar plexus block in the psoas compartment, located by neurostimulation. We used a single paramedial puncture at L4, following Chayen's approach, in patients undergoing uncemented hip arthroplasty under subarachnoid anesthesia with 0.5% bupivacaine.

Twenty patients were enrolled. We studied pain intensity on a visual analogical (VAS) scale every hour for the first 12 hours and every 2 hours for the next 12. The need for rescue analgesia, specifically non-steroidal anti-inflammatory drugs (NSAIDs) if pain was over 3 on the VAS and for morphine if analgesia was still insufficient. The patients assessed quality of analgesia received on a verbal scale. Complications were also noted.

VAS scores were under 3 throughout the first 11 hours, gradually rising to 4.7 at 24 h. Only 5 patients (2%) needed NSAIDs in the first 12 hours and non needed morphine. Sixteen patients (80%) needed a mean 1.6 doses of NSAIDs and 3 (15%) needed morphine for persistent pain or for pain greater than 5 on the VAS. On the verbal scale, only 10% reported experiencing intense pain during the postoperative period, whereas 90% said they had experienced mild or moderate pain.

A posterior lumbar plexus block using a single shot gives effective analgesia in the first 12 hours after surgery performed with spinal anesthesia. Continuous infusion through a catheter may provide better analgesia than that observed in this study.