Periarticular infiltration of 0.25% bupivacaine on top of femoral nerve block and intrathecal morphine improves quality of pain control after total knee arthroplasty: a randomized double-blind placebo controlled clinical trial.

OBJECTIVE: Find out if the addition of periarticular local anesthetic infiltration enhances the quality of postoperative pain control in patients with knee arthroplasty (TKA) in spinal anesthesia and intrathecal morphine plus single shot femoral nerve block (FNB). MATERIAL AND METHOD. Ninety-nine patients scheduled for TKA under spinal anesthesia were enrolled after written informed consent, and randomized into two groups with either periarticular injection of 20 ml 0.25% bupivacaine (B-gr n = 50) or isotonic saline solution (S-gr n = 49). All patients had intrathecal morphine 0.2 mg and single shot FNB with 20 ml bupivacaine 0.25% and were adjusted postoperative analgesic requirement via patient controlled analgesia with morphine. Effect of postoperative pain control and requirement of additional analgesics were recorded.

RESULTS: Randomization created comparable groups. Periarticular infiltration of bupivacaine in addition to femoral nerve block and intrathecal morphine was efficient and superior to saline regarding pain control, morphine consumption, and patient's satisfaction. More patients in B-gr did not require any supplement morphine in the first 24 hours (26% compared to 12.2%, p < or = 0.01). In patients who required morphine, B-gr had longer pain free period (25 hours compared to 14.8 hours, p < 0.001) and needed lower dose of morphine (5.16 mg compared to 8. 67mg, p = 0.005). No significant side effects were recorded.

CONCLUSION: Adding periarticular infiltration to femoral block and intrathecal morphine significantly enhances the quality of postoperative pain therapy in TKA patients. However combining three methods for analgesic therapy may be too much effort. Modifying infiltration techniques including continuous application needs further research.