The relative analgesic value of a femoral nerve block versus adductor canal block following total knee arthroplasty: a randomized, controlled, double-blinded study.



Multiple comparative studies report that adductor canal blocks provide similar pain relief to femoral nerve blocks following total knee arthroplasty. However, adductor canal blockade fails to anesthetize several important femoral nerve branches that contribute to knee innervation. We sought to clarify this anatomic discrepancy by performing both blocks in sequence, using patients as their own controls. We hypothesized that patients would experience additional pain relief following a superimposed femoral nerve block, demonstrating that these techniques are not equivalent.


Sixteen patients received continuous adductor canal block before undergoing knee arthroplasty under general anesthesia. In the recovery room, patients reported their pain score on a numeric scale of 0-10. Once a patient reached a score of five or greater, he/she was randomized to receive an additional femoral nerve block using 2% chloroprocaine or saline sham, and pain scores recorded every 5 min for 30 min. Patients received opioid rescue as needed. Anesthesiologists performing and assessing block efficacy were blinded to group allocation.


Patients randomized to chloroprocaine versus saline reported significantly improved median pain scores 30 min after the femoral block (2.0 vs. 5.5, P = 0.0001). Patients receiving chloroprocaine also required significantly fewer morphine equivalents during the 30 min post-femoral block (1.0 vs. 4.5 mg, P = 0.03).


Adductor canal block is a useful technique for postoperative pain following total knee arthroplasty, but it does not provide equivalent analgesic efficacy to femoral nerve block. Future studies comparing efficacy between various block sites along the thigh are warranted.





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Publication Info

Gadsden, Jeff C, Siddharth Sata, W Michael Bullock, Amanda H Kumar, Stuart A Grant and Joshua R Dooley (2020). The relative analgesic value of a femoral nerve block versus adductor canal block following total knee arthroplasty: a randomized, controlled, double-blinded study. Korean journal of anesthesiology, 73(5). pp. 417–424. 10.4097/kja.20269 Retrieved from

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Jeffrey Charles Gadsden

Professor of Anesthesiology

As Chief of the division of Orthopedic, Plastic and Regional Anesthesiology, my research interests lie in the efficacy of peripheral nerve blockade for acute postoperative pain control, research into educational methods for teaching regional anesthesia procedures, and the safe provision of regional anesthesia in the trauma setting.


William Michael Bullock

Assistant Professor of Anesthesiology

Amanda Hong Kumar

Assistant Professor of Anesthesiology

Dr. Amanda Kumar received her M.D. from Johns Hopkins University, then completed her residency in anesthesiology at Stanford University where she served as chief resident. She came to Duke in 2016 for a fellowship in regional and ambulatory anesthesia, and has stayed on as an assistant professor. She is passionate about medical education, and is the program director for the ACGME-approved Regional Anesthesiology and Acute Pain Medicine fellowship. She is heavily involved in medical simulation for all levels of learners, and is the graduate medical education simulation liaison for Duke's Human Simulation and Patient Safety Center. Her clinical and research interests are in regional anesthesiology and acute perioperative pain management. She is a part of Duke's Department of Anesthesiology perioperative leadership group. Nationally, she has been recognized as an associate member of the Association of University Anesthesiologists, associate faculty for the American Society of Regional Anesthesia and Pain Medicine, and is a subcommittee member for the American Society of Anesthesiologists. 


Joshua Ryan Dooley

Assistant Professor of Anesthesiology

Fellowship trained Ambulatory/Regional Anesthesiologist with a focus on excellent patient care including postoperative pain control as well as education of residents and fellows.

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