Femoral Nerve Block Versus Adductor Canal Nerve Block for Peri-Operative Analgesia Following Anterior Cruciate Ligament (ACL) Reconstruction: Evaluation of Post-operative Pain and Strength

Currently, because of its good track record, femoral nerve block is the modality of choice for post-operative pain control following elective anterior cruciate ligament reconstruction at our institution. It has been proven in the literature to provide good post-operative pain analgesia following this procedure (1). However, femoral nerve block is not without its concerns, including the concern for long-term quadriceps weakness (2). Benefits of decreased use of Femoral Nerve Block include the decreased incidence of side effects and/or complications, and use of quadriceps for immediate rehabilitation. Benefits of Adductor canal nerve block include possible equivalent pain control with the avoidance of motor de-innervation and its deleterious adverse effect of quadriceps weakness postoperatively. Adductor canal nerve block has proven to be effective in other orthopaedic procedures involving the knee including total knee arthroplasty (3). This results of this study will give more information on how to better control pain in the post-op period while minimizing the deleterious side effects for patients undergoing ACLreconstruction.

All patients over the age of 16 undergoing primary or revision anterior cruciate ligament reconstruction with the use of bone-patellar-bone autograft are eligible for the study. Patients will be randomized pre-operatively to receive either an adductor canal nerve block (single injection) or a femoral nerve block (single injection). A single dose of 30 mL of 0.25% marcaine is injected for femoral nerve block and 20 mL of 0.25% marcaine for Adductor Canal nerve block. These procedures will be performed by the attending anesthesiologist prior to surgery. After surgery the patient will record their pain levels using visual analog scale (VAS) score in a daily diary for the first 5 post-operative days. They will also record all medication requirements, both narcotic and non-narcotic analgesic medications. The patient will be tested on their ability to perform a straight leg raise in the post-anesthesia care unit (PACU) and at their first post-operative visit.

Inclusion criteria

• Primary ACL Reconstruction with use of Bone-Patellar-Bone Autograft
• Age 16 or older

Exclusion criteria

• Patients under 16
• The use of Allograft,
• The use of hamstring autograft
• The use quadriceps autograft
• Patients allergic to active ingredients in the injection.