BackgroundThe PROSPECT (Procedure-Specific Postoperative Pain Management) Group recommended a single injection femoral nerve block in 2008 as a guideline for analgesia after total knee arthroplasty. Other authors have recommended the addition of sciatic and obturator nerve blocks. The lateral femoral cutaneous nerve is also involved in pain syndrome following total knee arthroplasty. We hypothesized that preoperative blocking of all four nerves would offer superior analgesia to femoral nerve block alone.MethodsThis is a prospective, randomized, controlled, and observer-blinded clinical study. A total of 107 patients were randomly assigned to one of three groups: a femoral nerve block group, a multiple nerve block group, and a control group. All patients were treated postoperatively using patient-controlled intravenous analgesia with morphine. Pain intensity at rest, during flexion and extension, and morphine consumption were compared between groups over three days.ResultsA total of 90 patients completed the study protocol. Patients who received multiple nerve blocks experienced superior analgesia and had reduced morphine consumption during the postoperative period compared to the other two groups. Pain intensity during flexion was significantly lower in the “blocks” groups versus the control group. Morphine consumption was significantly higher in the control group.ConclusionsPain relief after total knee arthroplasty immediately after surgery and on the first postoperative day was significantly superior in patients who received multiple blocks preoperatively, with morphine consumption significantly lower during this period. A preoperative femoral nerve block alone produced partial and insufficient analgesia immediately after surgery and on the first postoperative day. (Clinical trial registration number (NIH): NCT01303120)

Background: Multiple nerve blocks (MNB) provide excellent time-limited perioperative analgesia following total knee arthroplasty. Both perineural and systemic use of dexamethasone (DXM) as an adjuvant to local anesthetic prolong the duration of single-shot MNB. We hypothesized that preoperative perineural injection of DXM prolongs analgesia after MNB more than the same dose of intravenous (IV) DXM injection due to direct action on the nerves and not only by a systemic action mechanism.