A modified fascia iliaca compartment block has significant morphine-sparing effect after total hip arthroplasty

We assessed whether a modified fascia iliaca compartment block in unilateral total hip arthroplasty provides a morphine-sparing effect in the first 24 hours. This involved a randomised, double blind study of 44 patients. Both groups received a modified fascia iliaca block with the trial group receiving 30 ml 0.5% bupivacaine with 1:200,000 adrenaline, 150 microg clonidine and 9 ml 0.9% saline and the control group receiving 40 ml 0.9% saline. Otherwise both groups received identical care with a subarachnoid block for operative anaesthesia. Patient-controlled morphine analgesia was commenced postoperatively and data were collected at three, six, 12 and 24 hours post commencement of surgery. We found that the trial group used less morphine at 12 and 24 hours (P < 0.001). The median morphine usage at 24 hours was 37.5 mg in the control patients and 22 mg in the trial patients. Pain scores were similar between groups. We conclude that a modified fascia iliaca compartment block has a significant morphine-sparing effect in unilateral total hip arthroplasty.