Modified continuous femoral three-in-one block for postoperative pain after total knee arthroplasty

We prospectively studied the continuous "modified" femoral three-in-one blo ck for postoperative pain after total knee arthroplasty. Sixty-two patients undergoing elective knee arthroplasty under spinal anesthesia with bupivac aine (B) and fentanyl were randomized to receive 0.2% B, 0.1% B, or placebo at 10 mL/h for 48 h after an initial bolus of 30 mt of the same solution v ia the femoral block catheter. The catheters were inserted under the fascia iliaca using a "double pop" technique and a peripheral nerve stimulator an d were advanced 15-20 cm cranially. Venous plasma levels of B, desbutylbupi vacaine, and 4-hydroxy B were measured daily for 3 days. All patients recei ved patient-controlled analgesia with morphine and indomethacin suppositori es for 48 h. Using computed tomography, we evaluated the catheter location for 20 patients. The catheter tips, located superior to the upper third of the sacroiliac joint in the psoas sheath, were labeled as ideally located. The group receiving 0.2% B had a larger block success rate, smaller morphin e consumption in the immediate postoperative period (15 vs 22 mg) and durin g the first postoperative day (9 vs 18 mg), and achieved a greater range of motion in the immediate postoperative period (91 degrees +/- 10 degrees vs 80 degrees +/- 13 degrees). Visual analog scores for pain during both rest and activity were low but similar between the groups. Forty percent of the catheters evaluated were ideally located. Ideal location and use of 0.2% B resulted in 100% success of blockade of all three nerves. The S1 root was blocked in up to 76% of patients. The plasma levels of B, 4-hydroxy B, and desbutylbupivacaine were below the toxic range during the infusion. We conc lude that continuous fascia iliaca block with 0.2% B results in opioid-spar ing and improved range of motion during the immediate postoperative period. Larger doses of bupivacaine may safely be used in the immediate postoperat ive period if needed. Implications: Continuous fascia iliaca block with 0.2 % bupivacaine reduces opioid requirements and improves range of motion in t he immediate postoperative period compared with a placebo and 0.1% bupivaca ine. Plasma levels are below the toxic range with this dose. Only 40% of th e catheters are positioned in the ideal location. With the smaller dose of bupivacaine, the success rate with this block is small.