Femoral block provides superior analgesia compared with intra-articular ropivacaine after anterior cruciate ligament reconstruction

Abstract

Background and objectives: Arthroscopic anterior cruciate ligament (ACL) reconstruction of the knee is a painful procedure requiring intensive postoperative pain management. This prospective study investigates analgesic quality after a femoral block as compared with intra-articular injection of local anesthetic.

Methods: Eighty patients scheduled for elective ACL repair under general anesthesia were included in our study. Upon completion of surgery, the patients were randomly assigned into 1 of 2 groups: femoral group (n = 40) received a femoral block with 20 mL 1% ropivacaine; intra-articular group (n = 40) received 20 mL 1% ropivacaine injected intra-articularly. During the first 24 hours after surgery, all patients received 2 g propacetamol and 100 mg ketoprofen, intravenously. Additional postoperative analgesia was available with parenteral morphine if required. Analgesic duration was defined as the time from end of surgery to the first requirement for a supplemental analgesic. Data collection included patient demographics, visual analog scale (VAS) scores, analgesic duration, and morphine use. Analysis of variance (ANOVA) test was used to compare the 2 groups.

Results: VAS score in the recovery room and during rehabilitation was higher in the intra-articular group than in the femoral group (P <.001). Morphine use was lower in the femoral group than in the intra-articular group (P <.001). Similarly, analgesic duration was longer in the femoral group than the intra-articular group (P <.0001).

Conclusions: Compared with intra-articular injection of local anesthetic, femoral nerve block (FNB) provides better analgesia and allows a significant morphine-sparing effect after ACL repair.