The efficacy of the psoas compartment block versus the intrathecal combination of morphine, fentanyl and bupivacaine for postoperative analgesia after primary hip arthroplasty: a randomized single-blinded study

Purpose: Intrathecal morphine and psoas compartment block represent two accepted techniques to provide postoperative analgesia after hip arthroplasty. We designed a prospective, randomized, single-blinded study to compare these two techniques. Methods: Forty patients scheduled for primary hip arthroplasty under general anesthesia were randomized to receive either an intrathecal administration of 0.1 mg morphine, 0.015 mg fentanyl and 15 mg hyperbaric bupivacaine (Group 1, n = 20) or a psoas compartment block with ropivacaine 0.475% 25 mL (Group II, n = 20). Pain scores, morphine consumption, associated side-effects were assessed for 48 hr postoperatively. In addition, patient's satisfaction and acceptance of the postoperative analgesic technique were also recorded. Results: During the first 24 hr, pain scores (12 +/- 27 vs 24 +/- 25 at H+12,12 +/- 46 vs 20 +/- 26 mm at H+24, 16 +/- 19 vs 20 +/- 29 mm at H+36) and tramadol consumption (30 +/- 70 vs 210 +/- 400 mg at H+12, 180 +/- 120 vs 320 +/- 100 mg at H+24) were slightly lower in Group I than in Group II, but there were no statistically significant differences. Itching was the most frequent side-effect occurring in 45% of cases in Group I vs 10% in Group If (P < 0.05). No major complication occurred. There was no difference in satisfaction scores between the two groups. Conclusion: Intrathecal administration of a combination of morphine, fentanyl and bupivacaine and single-shot psoas compartment block both provide very good postoperative analgesia after primary hip arthroplasty.