Intravenous regional analgesia using morphine. The effect on postoperative pain following total knee arthroplasty

Background: We hypothesised that any peripheral action of morphine may contibute to improved postoperative analgesia. The aim of this study was to evaluate the analgesic efficacy of morphine administered preoperatively into an exsanguinated limb prior to total knee arthroplasty.
Methods: A randomised, double-blind, controlled study was performed in 50 patients having total knee arthroplasty surgery. Patients were divided into two groups. In the study group, 0.125 mg/kg morphine in 60 ml of saline was administered intravenously (iv) into the exsanguinated operative limb via a can-nula in the foot. A saline intramuscular (im) injection was administered into the opposite leg. The control group received 60 ml saline iv into the operative leg and 0.12 5mg/kg morphine im into the opposite leg. Pain was assessed postoperatively using a 10-point visual analogue scale and by comparing morphine requirements and demand: delivery ratios from a patient-controlled analgesic pump.
Results: We found no statistically significant difference between the groups in relation to any of the analgesic measures employed.
Conclusions: Intravenous regional analgesia using morphine provides no analgesic advantage over the intramuscular route from 6–24 h postoperatively.