Continuous femoral nerve block versus intra-articular injection for pain control after anterior cruciate ligament reconstruction.

BACKGROUND: Continuous femoral nerve blocks have been recommended for postoperative pain control after anterior cruciate ligament reconstruction.

HYPOTHESIS: A pain control protocol involving a continuous ropivacaine femoral nerve block will decrease pain and narcotic use in the first 24 hours after surgery compared with a postoperative pain control protocol involving an intra-articular injection of bupivacaine/morphine.

STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 2.

METHODS: Ninety subjects, aged 15 years or older, who were receiving arthroscopically assisted bone-patellar tendon-bone anterior cruciate ligament reconstruction were randomly assigned to 2 groups. The first group received a ropivacaine continuous femoral nerve block and oral hydrocodone (block group). The second group received an intra-articular bupivacaine/morphine injection and oral oxycodone (injection group). Patients in both groups could receive intramuscular injection of hydromorphone for breakthrough pain; most patients in the block group also received bolus doses of ropivacaine through the femoral catheter. Subjects rated their worst, average, and current pain levels using a visual analog scale and category-ratio scale the morning after surgery. Postoperative narcotic pain medication use was converted to morphine-equivalent doses.

RESULTS: Postoperative pain ratings did not differ between the treatment groups. The largest difference in pain ratings between the groups was 0.5 cm for worst pain level (P = .345). Total narcotic use did not differ significantly between groups (1.1 morphine-equivalent doses in both groups; P = .671).

CONCLUSIONS: Continuous femoral block with ropivacaine appeared to have no clinical advantage in the immediate postoperative period after anterior cruciate ligament reconstruction when compared with an intra-articular injection of bupivacaine/morphine. Both methods are effective for pain control after anterior cruciate ligament reconstruction.