The Journal of Bone and Joint Surgery December 1 2007, Volume 89, Issue 12 Christopher E. Mutty, MD1, Erik J. Jensen, MD2, Michael A. Manka, Jr., MD2, Mark J. Anders, MD2 and Lawrence B. Bone, MD2 Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated. Background: Diaphyseal and distal femoral fractures are painful injuries that are frequently seen in patients requiring a trauma work-up in the hospital emergency department prior to definitive management. The purpose of this study was to determine whether a femoral nerve block administered in the emergency department could provide better pain relief for patients with femoral fractures than currently used pain management practices. Methods: Patients who presented with an acute diaphyseal or distal femoral fracture were identified as potential candidates for this study. Eligible patients were randomized by medical record number to receive either (a) the femoral nerve block (20 mL of 0.5% bupivacaine) along with standard pain management or (b) standard pain management alone (typically intravenous narcotics). The pain was assessed with use of a visual analog scale at the initial evaluation and at five, fifteen, thirty, sixty, and ninety minutes following the initial evaluation. Fifty-four patients were enrolled in the study from April 2005 to May 2006. Thirty-one patients received a femoral nerve block, and twenty-three patients received standard pain management alone. Results: Baseline scores on the visual analog pain scale did not differ between the groups at the initial evaluation. The patients who received a femoral nerve block (along with standard pain management) had significantly lower pain scores at five, fifteen, thirty, sixty, and ninety minutes following the block than did the patients who received standard pain management alone (p < 0.001). The score on the visual analog pain scale across these time-points was an average of 3.6 points less (on a 10-point scale) for those who received the block. There were no infections, paresthesias, or other complications related to the femoral nerve block. Conclusions: The acute pain of a diaphyseal or distal femoral fracture can be significantly decreased through the use of a femoral nerve block which can be administered safely in the hospital emergency department. Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.