Background: Continuous femoral or lumbar plexus blocks have been demonstrated to provide effective postoperative analgesia of the lower extremity following total joint arthroplasty. The purpose of this study was to compare these two techniques when used with intravenous patient-controlled analgesia and the use of patient-controlled analgesia alone for postoperative pain management following unilateral primary hip arthroplasty.

Methods: Two hundred and twenty-five patients undergoing unilateral total hip arthroplasty for a diagnosis of osteoarthritis were randomly allocated into one of three postoperative treatment groups: continuous lumbar plexus block with patient-controlled analgesia, continuous femoral block with patient-controlled analgesia, and patient-controlled analgesia alone. Scores on a visual analog pain scale administered during physiotherapy twenty-four hours postoperatively were used as the primary outcome measured. Secondary outcomes included scores on a visual analog pain scale at rest, hydromorphone consumption, opioid-related side effects, complications, sensory and motor blockade, and patient satisfaction.

Results: Continuous lumbar plexus block significantly reduced pain scores during physiotherapy on postoperative day 1 (p < 0.0001) and day 2 (p < 0.0001) compared with either continuous femoral block or patient-controlled analgesia alone. There were no significant differences for pain at rest between the two regional analgesic techniques. Both regional anesthesia techniques significantly reduced total hydromorphone consumption (p < 0.05) and delirium (disorientation to time and/or place) compared with patient-controlled analgesia alone (p < 0.023). In addition, the use of continuous lumbar plexus block was associated with fewer patients with opioid-related side effects (p < 0.05), greater distances walked (p < 0.05), and enhanced patient satisfaction (p < 0.05) compared with the use of a continuous femoral nerve block with patient-controlled analgesia or with patient-controlled analgesia alone.

Conclusions: Continuous lumbar plexus and femoral blocks significantly reduce the need for opioids and decrease related side effects. Continuous lumbar plexus block is a more effective analgesic modality than is a continuous femoral block or patient-controlled intravenous administration of hydromorphone alone during physical therapy following primary unilateral total hip arthroplasty.

Level of Evidence: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.