Background and Objectives The quality of analgesia and subsequent morphine requirements following spinal anesthetic block (SAB) or combined sciatic and femoral (3-in-1) block (SFB) for total knee arthroplasty were compared.

Methods The 39 patients studied were randomly assigned to receive either SAB (n = 19) or SFB (n = 20). All patients received a standardized general anesthetic, patient-controlled analgesia, and regular diclofenac. Visual analog pain scores and morphine requirements were recorded for 48 hours following surgery. Observations were grouped into four 12-hour periods. Pain scores (0-10 cm) were expressed as 95% confidence intervals; the criterion for analgesic success was a confidence interval in the range 0-3 cm.

Results Although pain-free on awakening, the SAB patients failed to achieve analgesic success in any of the four periods, while the SFB patients did so in three of the four periods. Morphine consumption was significantly higher in the SAB group during the first two periods but similar to the SFB group thereafter.

Conclusion In comparison with SAB, SFB resulted in superior analgesia and reduced morphine consumption for the first 24 hours following total knee arthroplasty.