USG-Guided Adductor Canal Block

USG-Guided Adductor Canal Block in Regional Anesthesia and Pain Medicine


Ultrasound-guided (USG) nerve blocks have revolutionized regional anesthesia and pain management, offering precise and effective pain relief for various surgical procedures. Among these techniques, the USG-guided Adductor Canal Block (ACB) has emerged as a valuable tool for providing analgesia, particularly in knee and lower extremity surgeries. This chapter delves into the intricacies of the ACB, highlighting its benefits, techniques, and clinical applications.

Understanding the Adductor Canal Block

The Adductor Canal Block targets the saphenous nerve, a sensory branch of the femoral nerve, within the adductor canal. The adductor canal, also known as Hunter’s canal, is an aponeurotic tunnel in the middle third of the thigh, providing a conduit for the femoral artery, vein, and saphenous nerve. By administering local anesthetic in this canal, the ACB offers effective analgesia for surgeries involving the knee and medial lower leg, while preserving motor function in the quadriceps muscles.

Benefits of USG-Guided Adductor Canal Block

The USG-guided Adductor Canal Block offers several advantages:

  1. Targeted Analgesia: The ACB provides focused pain relief to the medial aspect of the knee and lower leg, making it particularly effective for knee surgeries such as total knee arthroplasty (TKA) and anterior cruciate ligament (ACL) reconstruction.
  2. Minimal Motor Blockade: By sparing the motor function of the quadriceps muscles, patients retain their ability to mobilize early postoperatively, facilitating faster rehabilitation and recovery.
  3. Enhanced Safety: Ultrasound guidance enhances the precision of the block, reducing the risk of complications associated with blind or landmark-based techniques.
  4. Reduced Opioid Consumption: Effective regional anesthesia reduces the need for systemic opioids, minimizing opioid-related side effects and improving overall patient outcomes.

Indications and Applications

The USG-guided Adductor Canal Block is indicated for a variety of surgical procedures and pain management scenarios, including:

  1. Total Knee Arthroplasty (TKA): Adductor Canal Block provides excellent postoperative analgesia, reducing pain scores and opioid requirements and facilitating early mobilization.
  2. Anterior Cruciate Ligament (ACL) Reconstruction: The block offers effective pain relief for this common sports injury surgery, aiding in faster recovery and rehabilitation.
  3. Knee Arthroscopy: Adductor Canal Block benefits various arthroscopic procedures, providing targeted analgesia with minimal impact on quadriceps strength.
  4. Medial Lower Leg Surgeries: Procedures involving the medial aspect of the lower leg, such as saphenous vein stripping or varicose vein surgery, can benefit from ACB.
  5. Chronic Pain Management: In cases of chronic pain syndromes affecting the knee and medial lower leg, ACB can be employed as part of a multimodal pain management strategy.
  6. Cryoneurolysis: Cryoneurolysis can be used for acute and chronic pain management, including chronic knee osteoarthritis.

The technique of USG-Guided Adductor Canal Block

Performing the USG-guided Adductor Canal Block requires a systematic approach to ensure accuracy and safety:

  1. Patient Positioning: The patient is positioned supine with the leg slightly externally rotated. The knee can be slightly flexed to aid in visualization of the adductor canal.
  2. Ultrasound Visualization: A high-frequency linear ultrasound probe is placed transversely on the mid-thigh to identify the anatomical landmarks. The adductor canal is visualized as a hypoechoic space beneath the sartorius muscle, with the femoral artery and vein as key landmarks.
  3. Needle Insertion: Using an in-plane technique, a 22-gauge needle is inserted laterally to medially, aiming for the space adjacent to the femoral artery within the adductor canal.
  4. Injection of Local Anesthetic: Once the needle tip is confirmed to be in the correct position, local anesthetic (e.g., 10-20 mL of 0.25-0.5% ropivacaine or bupivacaine) is injected incrementally, ensuring adequate spread around the saphenous nerve.
  5. Confirmation: Ultrasound visualization of the local anesthetic spread within the adductor canal confirms the success of the block.

Complications and Considerations

While the USG-guided Adductor Canal Block is generally safe, awareness of potential complications and considerations is crucial:

  1. Local Anesthetic Toxicity: Careful dosing and incremental injection help minimize the risk of local anesthetic systemic toxicity (LAST).
  2. Nerve Injury: Ultrasound guidance significantly reduces the risk of inadvertent nerve injury by allowing real-time visualization of needle placement.
  3. Vascular Injury: Avoiding the femoral artery and vein during needle insertion is critical to prevent vascular injury and hematoma formation.
  4. Incomplete Block: Inadequate spread of local anesthetic may result in incomplete analgesia, necessitating additional analgesic measures.


The USG-guided Adductor Canal Block is a valuable addition to the armamentarium of regional anesthesia techniques, offering effective and targeted pain relief for knee and medial lower leg surgeries. Its ability to provide analgesia while preserving motor function makes it particularly advantageous for enhancing postoperative recovery and patient satisfaction. By leveraging the precision of ultrasound guidance, anesthesiologists can perform the ACB with confidence, ensuring optimal outcomes in regional anesthesia and pain management.

As the field of regional anesthesia continues to evolve, the USG-guided Adductor Canal Block stands out as a testament to the advancements in pain management techniques, emphasizing the importance of precision, safety, and patient-centered care in modern anesthesia practice.