Intraoperative Direct vs Postoperative Ultrasound Guided Adductor Canal Nerve Block After Total Knee Arthroplasty

Total knee arthroplasty (TKA) is a successful alternative to treat late stage knee osteoarthritis (OA). Pain management has been one of the main focuses of postoperative care. Most surgeons prefer a comprehensive multimodal approach including preoperative pharmacological treatment, intraoperative infiltration with complex drug mixes and postoperative peripheral nerve block.

The most common postoperative nerve block alternative is the proximal femoral nerve block (FNB) which has shown improvements on postoperative pain measured by reduced opioid consumption and decreased pain at rest. Its main detractors argue that the motor nerve block effect is deleterious to early ambulation and have promoted adductor canal nerve blocks (ACB). Described by Lund et al in 2011, ACB block main femoral pain sensory contributors to the knee (articular branches of obturator nerve, vastus medialis branch and saphenous nerve) but is more distal to most motor branches to the quadriceps allowing near to normal quadriceps strength.

Standard ACB block is performed under ultrasound guidance after surgery completion, still in the operating room (OR). Recent literature has shown the anatomic feasibility of intraoperative ACB via blunt suprapatellar dissection in standard medial parapatellar TKA approaches. The study seeks to determine the effectiveness of standard ultrasound guidance ACB compared with intraoperative ACB.

Inclusion criteria

• Primary total knee arthroplasty
• Unilateral
• American Society of Anesthesiologists (ASA) score I, II or III
• Accepts spinal anesthesia

Exclusion criteria

• General anesthesia
• Chronic kidney disease
• Drug or alcohol abuse
• Chronic opioid use
• Allergic to bupivacaine or similar