Regional Analgesia After Total Knee Replacement

Abstract

Our protocol was written before the modification for posterior lumbar plexus block by using the peripheral nerve stimulator became popular, and we totally agree that the posterior lumbar plexus block is superior to the femoral three-in-one block. We also agree with regard to the need for patient-controlled analgesia morphine in this subset of patients with the femoral block. In our study, we used the patient-controlled analgesia to allow patients to dose themselves to achieve similar analgesic endpoints, and morphine consumption was used as an indicator of the severity of the pain. Thus, our pain scores are similar, but the morphine consumption is not. Evaluation of the femoral catheter location was done entirely for experimental purposes and is not routinely done for this block in our institution. The investigation, however, teaches a good point that not all catheters reach where you aim to put them. Although there is no doubt about the presence of opiate receptors in the spinal cord and peripheral nerve nociceptive terminals, their presence in the peripheral axons has not been proven, to our knowledge. Systemic absorption of opiates delivered in the periaxonal area could per se provide some analgesia. We did not use opiates in our infusion to keep the study as clean as possible. S. Ganapathy FRCA FRCPC J. Watson FRCPC R. Wasserman FRCPC DABA K. Armstrong FRCPC D. G. Chess FRCSC