Persistent Quadriceps Weakness with Femoral Nerve Block

Abstract

Purpose: Femoral nerve blocks (FNB) for anterior cruciate ligament reconstruction (ACLR) can effectively reduce post-operative pain, though this is tempered with the potential for quadriceps weakness, and subsequent concerns regarding impeded rehabilitation. The purpose of this retrospective study was to assess post-ACLR differences in International Knee Documentation Committee Subjective Knee Form (IKDC) scores in patients who did not (NB) and did (FB) receive perioperative FNB. Methods: A retrospective review was performed to identify all adults undergoing ACLR at Tripler Army Medical Center between January 2013 and August 2016, with International Knee Documentation Committee (IKDC) outcome scores from pre-surgery to 6-12 months post-surgery. Patients were then divided into two groups, with the FB group being patients who received femoral nerve blocks (FNBs), and NB group patients not receiving a block. Demographics included age, sex, BMI, and ASA category. IKDC scores were converted to normative values. Variables were analyzed using Mann-Whitney-U, ANCOVA, and Chi-square tests. Results: A total of 123 ACLR patients were identified with complete IKDC scores, of which 41 did not receive a femoral nerve block. Preoperatively, IKDC scores were statistically similar between NB (Mean=40.82,SD=15.82) and FB groups (Mean=40.03,SD=15.36), (p=.79). There were no significant group differences in time-to-follow-up (p=.30), age (p=.74), or BMI (p=.11), gender (p=.27) or ASA category (p=.26). A repeated measures ANCOVA examined whether the treatment groups differed in IKDC score changes from pre-surgery to follow-up. Both groups had a significant increase in IKDC score from pre-surgery to follow-up (p<0.008). However, there was no significant difference between groups (p<0.8) (Figure 2). Conclusion: This retrospective review of outcomes after ACLR surgery indicate knee functioning improvements after ACLR did not differ between patients who did and did not receive FNB. Future rigorous studies are needed to fully examine FNB effects on other patient-reported and clinical outcomes after ACLR. Data Sources: PubMED, Cochrane Library, CINAHL, and Google Search. Keywords: International Knee Documentation Committee, IKDC, anterior cruciate ligament, ACL, reconstruction, repair, surgery, femoral nerve block, nerve block, quadriceps