Femoral Nerve Block in Anterior Cruciate Ligament Surgery: A Prospective Randomized Trial

Abstract

Early rehabilitation is essential after anterior cruciate ligament (ACL) surgery. Femoral nerve block (FNB) is a frequently used method to control post-operative pain in arthroscopic and reconstructive knee surgery; however, it is still unknown how to apply this procedure to improve analgesia without affecting early rehabilitation. Objective: To compare the effectiveness of pain management after a single dose of FNB vs a continuous FNB infusion during the first 48 hours after ACL surgery. Methodology: Forty-three patients older than 18 years, ASA I-II, underwent ACL reconstruction with an autograft. Patients were prospectively randomised into two separate groups: Group 1 (G1) received a single dose of FNB with bupivacaine diluted in 10 mL saline solution. Group 2 (G2) received continuous FNB infusion with bupivacaine and epinephrine (1:300.000) for 48 hours. Pain was assessed at rest and with controlled passive motion of the knee. Thigh hypo-aesthesia and the need for additional analgesia were evaluated at 6, 12, 24, and 48 hours. Statistical analysis was performed with Fisher's exact test (%) and Mann-Whitney's test (VAS). Statistical significance with P < .05. Results: FNB was successful in all patients, and thigh hypo-aesthesia was present in 100% of G2 vs. 17% in G1 at 24 hours, declining to 74% vs. 0% at 48 hours, respectively. Post-operative pain scores were low, and did not differ between the two groups. Additional analgesia was required in 33% of patients in G1 vs. 0% in G2. Conclusion: FNB is a successful method for controlling pain after ACL reconstruction. No statistical significance differences were found in pain control between techniques investigated.Level of Evidence type II.