for people ages 18 years and up (full criteria)
at San Francisco, California
study started
estimated completion
Principal Investigator
by Pedram Aleshi, MD



The purpose of this study is to compare the effects of a femoral nerve block vs. an adductor canal block on pain and quadriceps muscle strength for knee arthroscopy surgery.

Official Title

Effects of Ultrasound-guided Adductor Canal Block Versus Femoral Nerve Block on Pain and Quadriceps Strength After Ambulatory Knee Arthroscopic Surgery


Patients undergoing arthroscopic knee surgery (ACL and non-ACL surgery) typically receive an ultrasound-guided femoral nerve block or an adductor canal block in the pre-operative phase for post-operative pain control. While an effective method for post-operative analgesia, the femoral nerve block is associated with profound quadriceps weakness for the duration of the nerve block, which can impair ambulation, rehabilitation, and increase the risk of falls. The more distal adductor canal block, however, contains primarily sensory branches of the femoral nerve and has been been purported by small volunteer studies to provide equally effective analgesia with minimal motor block and quadriceps weakness (as compared to femoral nerve block). The investigators will prospectively randomize patients undergoing knee arthroscopy at the UCSF Orthopaedic Institute to receive either a single-shot femoral nerve or adductor canal block pre-operatively after taking baseline measurements of quadriceps strength (quantified by maximum voluntary isometric contraction). The quadriceps muscle strength will be checked 20 minutes after the nerve block to assess strength. All patients will subsequently undergo a general anesthetic. The primary outcome variable will be post-block quadriceps strength as a percentage of baseline from pre-block values. Secondary outcome variables that will also investigated include: VAS pain score in the post anesthesia recovery unit and post-operative day 1, time to onset of sensory block, duration of nerve blockade, block performance time, patient satisfaction score, perioperative opioid use, perioperative analgesic consumption, incidence of paresthesias, number of needle passes, incidence of post-operative nausea, vomiting, constipation, and any other complications.


Anterior Cruciate Ligament Tear Knee Meniscus Tear Knee arthroscopy ACL reconstruction Femoral block Adductor Canal Block Anterior Cruciate Ligament Injuries Ropivacaine Femoral Nerve Block Adductor Canal Nerve Block preoperative Femoral Nerve Block using 20ml of 0.5% ropivacaine Preoperative Adductor canal block with 0.75%% ropivacaine 13.3ml.


You can join if…

Open to people ages 18 years and up

  • American Society of Anesthesia I-III classification,
  • Scheduled for arthroscopic knee surgery (meniscal debridement/repair, ACL reconstruction)

You CAN'T join if...

  • Age younger than 18 years
  • Non-English speaking
  • Any contraindication for regional anesthesia, such as allergy to local anesthetics or opioids, -Coagulopaty or severe thrombocytopenia
  • Infection at puncture sites
  • Pre-existing neuropathy in operative limb
  • Need for post-operative nerve function monitoring
  • Dementia
  • Patient refusal
  • High pre-operative opioid requirements


  • UCSF Orthopedic Trauma Service accepting new patients
    San Francisco California 94158 United States

Lead Scientist at UCSF

  • Pedram Aleshi, MD
    Professor, Anesthesia, School of Medicine. Authored (or co-authored) 22 research publications


accepting new patients
Start Date
Completion Date
University of California, San Francisco
Phase 4 research study
Study Type
Expecting 108 study participants
Last Updated