Evaluating the Addition of Obturator Nerve Block to Adductor Canal Block for Total Knee Arthroplasty
Phase: PHASE4
Conditions: Knee Osteoarthritis, Knee Rheumatism
Sponsor: Icahn School of Medicine at Mount Sinai

 
 
 
Protocol Title: Evaluating the addition of obturator nerve block to adductor canal block for total knee 
arthroplasty 
PI: Christina Jeng 
NCT03326999 
Date: Sept 29, 2017 
 
 

Protocol Title: Evaluating the addition of obturator nerve block to adductor canal block for total knee 
arthroplasty 
Research Question: Does the addition of obturator nerve block to a regional anesthesia technique with 
adductor canal block and local infiltration analgesia for total knee replacement surgery reduce opioid 
consumption in the PACU?  
 
Primary objective: Compare the rate of IV opioid consumption in patients who receive a combination of 
adductor canal block, obturator nerve block, and local infiltration analgesia at the surgical site versus 
patients who receive adductor canal block and local infiltration analgesia.  
 
Secondary objectives: 
a. 
Measure the severity of pain at rest using an 11-point Likert scale at 1, 6, 12, 24 hour marks 
postoperatively in patients who receive adductor canal block, obturator nerve block, and local 
infiltration analgesia versus patients who receive adductor canal block and local infiltration analgesia 
b. 
Compare time to breakthrough pain after surgery in patients who receive adductor canal block, 
obturator nerve block, and local infiltration analgesia versus patients who receive adductor canal block 
and local infiltration  
c. 
Measure rate of post-operative nausea/vomiting in patients who receive adductor canal block, 
obturator nerve block, and local infiltration analgesia versus patients who receive adductor canal block 
and local infiltration  
d. 
Measure time to ambulation in patients who receive adductor canal block, obturator nerve 
block, and local infiltration analgesia versus patients who receive adductor canal block and local 
infiltration   
e. 
Compare analgesia satisfaction score at time of first postoperative followup visit in patients who 
receive adductor canal block, obturator nerve block, and local infiltration analgesia versus patients who 
receive adductor canal block and local infiltration. 
 
Background 
The management of postoperative pain after total knee arthroplasties remains a challenging issue.  Even 
though postoperative pain typically ranges from moderate to severe, patients are encouraged and 
expected to start physical therapy and ambulate as soon as possible because early rehabilitation may 
lead to improved long-term functional status of the knee.1 Integrated multimodal analgesic strategies 
have been employed for postoperative pain management; the aim of such strategies is to utilize 
different mechanisms of action to provide superior analgesia while limiting side effects and adverse 
events.2 Multimodal analgesic strategies for total knee arthroplasties most commonly combine regional 
anesthesia techniques, including femoral nerve block and local infiltration analgesia, with a combination 
of low-dose opioids, acetaminophen, and nonsteroidal anti-inflammatory drugs.2  

The optimal peripheral nerve block or combination of blocks is not yet known. Since the knee joint is 
innervated by an anterior and posterior group of sensory nerves, an approach that provides regional 
anesthesia to both groups seem reasonable. The femoral nerve block provides analgesia of the knee in 
the anteromedial region.3 However, despite the improved analgesia and shortened hospital stays 
provided by the use of femoral nerve blocks in total knee arthroplasties, the motor weakness that can 
be caused by these regional blocks can delay mobilization and increase the risk of falls.4  
Recently, the adductor canal block has become more frequently used because of claims that femoral 
nerve block can increase fall risk. The adductor canal block blocks the saphenous nerve and is primarily a 
sensory block, even though it can result in the partial motor block of the vastus medialis muscle. Overall, 
the adductor canal block has exhibited relative spring of quadriceps strength and was shown to be not 
inferior in providing analgesia and opioid consumption.5 
The obturator nerve block has also been utilized for total knee arthroplasties. The obturator nerve 
provides innervation to the posterior group of sensory nerves.6 The femoral nerve block has not been 
shown to provide consistent block of the obturator nerve, and the addition of sciatic nerve block to a 
femoral nerve block does not further improve analgesia of the posterior knee.3,7 However, the addition 
of the obturator nerve block to a femoral nerve block has been shown to improve postoperative 
analgesia after total knee arthroplasty.8 The addition of obturator nerve block to femoral triangle block 
has also been shown to reduce opioid consumption without impairing ambulation.9  
Based on the above studies, various multimodal analgesic strategies, including various combinations of 
regional anesthetic techniques, have been utilized, with varying success. There is no consensus on the 
optimal strategy that provides the most effective postoperative analgesia while preserving ambulation 
and limiting side effects such as nausea and vomiting. We believe that the obturator nerve block in 
addition to adductor canal block and local infiltration analgesia can target both the anterior and 
posterior distribution of nerves to the knee to provide superior analgesia while not limiting ambulation. 
To date, we are not aware of any studies that have examined this particular combination of regional 
anesthetic techniques. 
 
Primary and Secondary Study Endpoints 
Primary objective: Compare the rate of IV opioid consumption in patients who receive a combination of 
adductor canal block, obturator nerve block, and local infiltration analgesia at the surgical site versus 
patients who receive adductor canal block and local infiltration analgesia.  
 
Secondary objectives: 
f. 
Measure the severity of pain at rest using an 11-point Likert scale at 1, 6, 12, 24 hour marks 
postoperatively in patients who receive adductor canal block, obturator nerve block, and local 
infiltration analgesia versus patients who receive adductor canal block and local infiltration analgesia 
g. 
Compare time to breakthrough pain after surgery in patients who receive adductor canal block, 
obturator nerve block, and local infiltration analgesia versus patients who receive adductor canal block 
and local infiltration  

h. 
Measure rate of post-operative nausea/vomiting in patients who receive adductor canal block, 
obturator nerve block, and local infiltration analgesia versus patients who receive adductor canal block 
and local infiltration  
i. 
Measure time to ambulation in patients who receive adductor canal block, obturator nerve 
block, and local infiltration analgesia versus patients who receive adductor canal block and local 
infiltration   
j. 
Compare analgesia satisfaction score at time of first postoperative follow-up visit in patients 
who receive adductor canal block, obturator nerve block, and local infiltration analgesia versus patients 
who receive adductor canal block and local infiltration. 
 
Description of the Study Design 
If you agree to participate in this research study, the following information describes what may be 
involved. 
You study involvement will begin on the day of your surgery at Mount Sinai Hospital. Prior to starting 
surgery, you will undergo two regional anesthesia blocks. You will receive an intravenous medication 
called midazolam to reduce anxiety and help tolerate the procedures. One of them is called the 
adductor canal block, which is typically performed for your surgery regardless of the research study. An 
ultrasound will be used to identify the location of nerves in your upper leg, and a numbing medication 
called bupivacaine will be injected around the identified area. The other is called the obturator nerve 
block, which is being evaluated in this research study. Once again, an ultrasound will be used to identify 
the location of nerves in your upper leg close to the groin area, which will be appropriately draped. Once 
this area is identified, a solution will be injected which is either bupivacaine or saline that does not 
contain any active medication. Once these procedures are completed, the rest of the anesthesia for the 
surgery will proceed the same as if you are not part of the research study. This includes a spinal 
anesthesia that will make the lower part of your body numb, and any sedation given by the 
anesthesiologist to help you feel relaxed and comfortable enough to tolerate the surgery.   
After your surgery, you will be taken to a surgery recovery area before you are able to go to your own 
hospital room. There, you will be given a button to push to receive an intravenous opioid medication. 
You will have the freedom to decide when to receive the medication but it will be set up so that you 
cannot receive more than your doctors intended. You will also have nausea medications available. The 
study doctor will ask you about your pain level and nausea level. The doctor will also review how much 
opioid medication you received by pushing the button.   
You will periodically be asked questions regarding your pain and nausea and vomiting during the rest of 
your hospital stay. Your performance during your physical rehabilitation sessions will also be reviewed 
by study doctors.  
At your first postoperative visit with your surgeon after your discharge from the hospital, you will be 
asked about your pain levels after your discharge and your overall satisfaction with your pain control.  
The study treatment you get will be chosen by chance, like flipping a coin. Neither you nor the study 
doctor will choose what study treatment you get. You will have an equal chance of being given each 

study treatment. Neither you nor the study doctor will know which study treatment you are getting. This 
information could be obtained in an emergency, however.   
 
Description of Procedures Being Performed 
Subjects who consent to and are scheduled for total knee arthroplasty under regional anesthesia will be 
invited to participate in the study during a routine preoperative visit prior to surgery. The details of the 
study will be reviewed and written informed consent will be obtained.  
The patient will be randomized into the study group or the placebo group. On the day of surgery, the 
group allocation will be revealed to an anesthesiologist not part of the research study, who will receive 
specific instructions to prepare a injectate solution for the obturator nerve block, which will consist of 
0.25% bupivacaine for the study group or saline for the placebo group.  
The patient will receive midazolam for anxiolysis at the discretion of the attending anesthesiologist. An 
adductor canal block with 10mL 0.25% bupivacaine will be performed. An obturator nerve block will be 
performed with the previously prepared injectate solution. Patients will undergo spinal anesthesia with 
a 3mL solution of 0.75% bupivacaine. Sedation may be administered during surgery at the discretion of 
the anesthesiologist.  
Total knee arthroplasty will be performed by the orthopedic surgeon with insertion of bicopartmental or 
tricompartmental prostheses using a standard medial parapatellar approach and hand-mixed cementing 
techniques. A local intraarticular injection will be performed intraoperatively by the surgeon, as is 
routinely done for total knee arthroplasties by the surgeon involved in our study, regardless of research 
involvement.  
In the Post Anesthesia Care Unit, the patient will be administered hydromorphone using intravenous 
patient-controlled analgesia (PCA). Fentanyl will be administered if hydromorphone is not tolerated. 
Additional oral oxycodone consumption will also be recorded.  
Relevant preoperative, intraoperative, and postoperative data will be obtained from the anesthesia 
record, the EPIC electronic medical record. The patient will also be interviewed by study personnel at 
time of first post-discharge follow-up visit to obtain analgesia satisfaction scores. 
 
Description of the Source of Records that will be used to collect data about subjects  
As part of this research project, the research team at the hospital(s) involved in the research will collect 
your name, date of birth, telephone number, date of surgery, date of discharge, and medical record 
number. 
The researchers will also get information from your medical record including your electronic anesthesia 
record and electronic medical record that documents your postoperative care at Mount Sinai. They will 
also get information from your first postoperative visit with your surgeon.    
During the study the researchers will gather information by completing the chart review and interview 
explained in the description section of this consent. 

Description of data that will be collected including long-term follow-up 
In all disclosures outside of Mount Sinai, you will not be identified by name, social security number, 
address, telephone number, or any other direct personal identifier unless disclosure of the direct 
identifier is required by law. Some records and information disclosed may be identified with a unique 
code number. The Principal Investigator will ensure that the key to the code will be kept in a locked file, 
or will be securely stored electronically. The code will not be used to link the information back to you 
without your permission, unless the law requires it, or rarely if the Institutional Review Board allows it 
after determining that there would be minimal risk to your privacy. It is possible that a sponsor or their 
representatives, a data coordinating office, a contract research organization, may come to inspect your 
records. Even if those records are identifiable when inspected, the information leaving the institution 
will be stripped of direct identifiers.  Additionally, when applicable, the monitors, auditors, the IRB, the 
Office of Human Subjects Protection (OHRP) of the Department of Health and Human Services as well as 
the Food and Drug Administration (FDA) will be granted direct access to your medical records for 
verification of the research procedures and data. OHRP and FDA are authorized to remove information 
with identifiers if necessary to complete their task. By signing this document you are authorizing this 
access. We may publish the results of this research. However, we will keep your name and other 
identifying information confidential. 
 
Your authorization for use of your protected health information for this specific study does not expire. 
 
Description of instruments created by research team 
The data collection sheet created by the research team will be used to gather preoperative, 
intraoperative, and postoperative data relevant to the study. Preoperative data to be collected includes 
patient demographics including age and gender. Intraoperative data include duration of surgery, total 
narcotics administered during surgery, and total fluids administered. Postoperative data include total 
narcotics administered, pain scores at regular various intervals, incidence of postoperative nausea and 
vomiting, and time to ambulation. Data will also be extracted from the patient's first completed physical 
therapy session, including total distance ambulated, pain at time of assessment, and functional mobility 
impairment percentage. Post-discharge data to be collected include total dosage of narcotics used after 
discharge, pain score, and any complications. 
 
Where and when consent will be obtained 
Patients will be introduced to the study in the surgeon's office at 5 East 98th Street offices for the 
Department of Orthopedics (FPA). Patient will be informed about the study in more detail via telephone 
call prior to surgery. Official written consent will be obtained in the preoperative assessment area at 
Mount Sinai Hospital on the day of surgery. 
 
Waiting period for obtaining consent 

Official written consent will be obtained on the day of surgery. Patients will be given anywhere from 3 
days to 2 weeks from when they are first introduced to the study until time of obtaining consent. 
 
Description of health information that will be viewed, recorded, or generated 
As part of this research project, the research team at the hospital involved in the research will collect 
your name, date of birth, telephone number, date of surgery, date of discharge, and medical record 
number.  
The researchers will also get information from your medical record including your electronic anesthesia 
record and electronic medical record that documents your care during your recovery at Mount Sinai 
Hospital. They will also get information from your first postoperative visit with your surgeon.  
During the study, the researchers will gather information by completing the chart review and interview 
as explained in the description section of this consent.