Genicular Nerve Blocks for Arthroscopic Anterior Cruciate Knee Surgery: a Randomized Controlled Trial
Phase: PHASE4
Conditions: ACL, Anterior Cruciate Ligament Injuries
Sponsor: Hospital for Special Surgery, New York

 
Confidential 
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Genicular Nerve Blocks for Arthroscopic Anterior 
Cruciate Knee Surgery: A Randomized Controlled 
Trial 
 
FUNDER: 
Department of Anesthesiology 
PROTOCOL NO.: 
2022-1962 
VERSION & DATE: 
11/25/2024 
 
 
 
 
 
 
 
 
 
 
 
 
This document contains the confidential information of the Hospital for Special Surgery.  It is provided to you and your company’s personnel for 
review.  Your acceptance of this document constitutes an agreement that you will not disclose the information contained herein to others without 

 
Protocol Number: 2022-1962  
Version Date: 11/25/2024 
 
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the prior written consent of the Hospital for Special Surgery.  No other use or reproduction is authorized by Hospital for Special Surgery, nor does 
the Hospital for Special Surgery assume any responsibility for unauthorized use of this protocol. 
 
 
 
 
TABLE OF CONTENTS 
TABLE OF CONTENTS ............................................ 2 
PROTOCOL SYNOPSIS ........................................... 3 
1.0 
INTRODUCTION ............................................. 5 
2.0 
OBJECTIVE OF CLINICAL STUDY ............... 5 
3.0 
STUDY HYPOTHESES .................................. 5 
4.0 
STUDY DESIGN ............................................. 5 
4.1 
Study Duration ................................................................................................................ 5 
4.2 
Endpoints ....................................................................................................................... 6 
4.2.1 
Primary Endpoint ...................................................................................................... 6 
4.2.2 
Secondary Endpoints ................................................................................................ 6 
4.3 
Study Sites ..................................................................................................................... 6 
5.0 
STUDY POPULATION ................................... 6 
5.1 
Number of Subjects ........................................................................................................ 6 
5.2 
Inclusion Criteria............................................................................................................. 6 
5.3 
Exclusion Criteria ........................................................................................................... 6 
5.4 
Randomization ............................................................................................................... 7 
6.0 
PROCEDURES ............................................... 7 
6.1 
Surgical Procedure ......................................................................................................... 7 
6.2 
Medical Record Requirements ....................................................................................... 7 
6.3 
Data Collection ............................................................................................................... 7 
7.0 
STATISTICAL ANALYSIS .............................. 8 
8.0 
ADVERSE EVENT ASSESSMENT ................ 8 
9.0 
REFERENCES................................................ 8 
 
 
 

 
Protocol Number: 2022-1962  
Version Date: 11/25/2024 
 
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PROTOCOL SYNOPSIS 
Protocol Title: 
Genicular Nerve Blocks for Arthroscopic Anterior Cruciate Knee 
Surgery: A Randomized Controlled Trial 
Protocol Number: 
2022-1962 
Protocol Date: 
11/21/2022 
Sponsor: 
Department of Anesthesiology 
Principal 
Investigator: 
David H. Kim, MD 
Products: 
N/A 
Objective: 
The intervention to be studied is to see if the addition of the genicular 
nerve block (GEN) to our current peripheral nerve block regimen of 
adductor canal block (ACB) and infiltration between the popliteal artery 
and capsule of the posterior knee (IPACK) significantly reduces opioid 
consumption in first 24 hours after an anterior cruciate ligament repair 
with bone tendon bone autograft surgery. 
Study Design: 
Randomized Study 
Enrollment: 
192 
Subject Criteria: 
Inclusion: 
• 
Ambulatory arthroscopic unilateral anterior cruciate ligament 
repair surgery with bone tendon bone autograft 
• 
English-speaking 
• 
ASA I-III 
• 
BMI < 35 
 
Exclusion: 
• 
History of chronic pain syndromes 
• 
Chronic opioid use (daily morphine milligram equivalents > 30 mg 
for at least 3 months) 
• 
Contraindication to peripheral nerve blocks 
• 
Contraindication to neuraxial anesthesia 
• 
History of peripheral neuropathy or pre-existing neurological 
deficits 
• 
Psychiatric or cognitive disorder that prohibit patient from following 
study protocol 
• 
Allergy to local anesthetic or study medications 
• 
Multiligament surgery 
• 
History of substance abuse 
• 
Infection at the site of injection 
• 
diagnoses of Type I or Type II diabetes 
Study Duration: 
2 years 
Data Collection: 
Sources: EPIC, Medical Records, and Patient Reported. 
 
Variables: Name, MRN, DOB, Race, Ethnicity, Gender, Height, 
Weight, BMI, ASA class, email address, phone number, level of 

 
Protocol Number: 2022-1962  
Version Date: 11/25/2024 
 
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education, co-morbidities (diabetes, high blood pressure, cholesterol, 
rheumatological conditions, allergies), medications to manage pre-
existing conditions (opioids and non-opioids), surgery details (surgeon, 
anesthesiologist, surgery type, tourniquet use, duration), anesthesia 
details, DVT prophylaxis medications ordered and/or administered, 
length of PACU stay, time to meet discharge criteria, opioid 
consumption, IV PCA ordered, NRS pain scores, nerve block success, 
duration of blocks, ACB assessment, brief pain inventory, patient 
satisfaction. 
Statistical Analysis: 
1. Proposed analysis (e.g., student’s t-test, ANOVA, chi-
square, regression, etc.): two-sample t-test (one sided- 
alternative hypothesis OME reduction 0-24 hours mean (gen 
block) < mean (control) 
2. Interim analysis planned?: No 
3. Alpha level:  0.05 
4. Beta or power level:  0.8 
5. Primary outcome variable estimate (mean +/- s.d. for 
continuous outcome, frequency/percentage for 
categorical variable): 28.2  +/-  23.34 mg oral morphine 
equivalents 
6. Number of groups being compared (use 1 for paired 
analysis within the same subjects):  2 
7. Effect size or change expected between groups: 33% 
reduction in opioid consumption 0-24 hours after block time 
(9.31) 
8. Resulting number per group: 96 
9. Total sample size required: 192 (10% attrition added to 174 
needed for statistical significance)   
 
 
 
 

 
Protocol Number: 2022-1962  
Version Date: 11/25/2024 
 
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1.0 INTRODUCTION 
Genicular nerve blocks have been shown to provide effective analgesia for chronic osteoarthritis 
knee pain [1].  There are several publications supporting its use for chronic knee pain but there 
is a scarcity of literature in its use in the perioperative period.  Recently, it has been shown to 
provide effective analgesia for total knee arthroplasty [2].  This will be a novel application for it to 
be used for anterior cruciate ligament surgery.  There are only a couple of prospective and 
retrospective studies that showed promising analgesic benefits for anterior cruciate ligament 
repairs [3][4].  There are currently no randomized controlled trials published investigating the use 
of genicular nerve blocks for anterior cruciate ligament surgery. 
Researching novel innovative motor-sparing and opioid-sparing peripheral nerve blocks for have 
been the focus of our research team.  We have investigated the motor sparing benefits of the 
adductor canal block [5], the effective analgesic benefits of the IPACK block [6], the phrenic 
sparing benefits of the superior trunk block [7], and the analgesic benefits of the pericapsular 
nerve group block and lateral femoral cutaneous nerve [8]. Genicular nerve blocks would be a 
potential additive block that may further enhance the recovery of our knee surgeries, including 
unicondylar, total knee and anterior cruciate ligament repair patients. 
2.0 OBJECTIVE OF CLINICAL STUDY 
 
Since 2021, we have performed genicular nerve blocks on our patients at HSS and anecdotally 
seen immediate benefit in the patients via reduction of opioid consumption and earlier discharge.  
Recently, genicular nerve blocks have demonstrated significant and clinically meaningful reduction 
in opioid consumption in total knee arthroplasty patients.  The purpose of the study is to perform a 
randomized controlled trial on the patients who underwent anterior cruciate ligament repairs 
comparing our current standard regimen of peripheral nerve blocks, which includes an adductor 
canal block (ACB) and interspace between the popliteal artery and capsule of the posterior knee 
block (IPACK), to a new regimen that includes the addition of genicular nerve blocks.  
3.0 STUDY HYPOTHESES 
 
Genicular nerve blocks will significantly and clinically meaningfully reduce mean opioid 
consumption (in oral morphine equivalents) by 33% in the first 24 hours compared to the 
standard peripheral nerve block regimen. Genicular nerve blocks will significantly reduce mean 
NRS pain scores in the first 24 hours. Genicular nerve blocks will significantly reduce discharge 
times. Genicular nerve blocks will reduce opioid consumption and NRS pain scores in first 48 
hours. Genicular nerve blocks will have better scores on the brief pain inventory questionnaire 
and higher patient satisfaction. 
4.0 STUDY DESIGN 
 
4.1 
Study Duration 
January 2023 – November 2024 

 
Protocol Number: 2022-1962  
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4.2 
Endpoints 
4.2.1 
Primary Endpoint 
• 
Mean opioid consumption at 24 hours 
4.2.2 
Secondary Endpoints 
• 
Opioid consumption at PACU, 48, 72,96, 168 hrs: PACU (PACU arrival to removal 
from board), 48,72,96,168 hours after time zero (PACU arrival time) 
• 
NRS pain scores at PACU, 24, 48, 72, 96, 168 hrs: PACU (discharge ready time = 
recovery complete time), 24,48,72,96,168 hours after time zero (PACU arrival time) 
• 
Cumulative opioid consumption at 48, 72, 96 hours: sum of opioid used from 0-48 
hours, and 0-72 hours, and 0-96 hours. 
• 
Brief pain inventory (short form): Preoperatively, 24,48,72,96,168 hours 
• 
Patient satisfaction with pain treatment: PACU, 24, 48 hours 
• 
Duration of analgesic block: RA scripted phone call at 24 hours after block placement 
(or 48 hours if block still in place). Patients will be asked "When did your pain relief from 
the block completely"  
• 
Success of ACB: numbness in the saphenous distribution will be assessed in the PACU 
by an anesthesiologist or RA 
• 
Time of readiness for pacu discharge: from pacu arrival time to recovery complete 
time. 
• 
Length of PACU stay: from pacu arrival time to patient removed from board time 
• 
Adverse events: Incidence of neuropraxia (neurological symptoms over 3 days), LAST, 
and infection 
4.3 
Study Sites 
 
This study will take place at the Hospital for Special Surgery (HSS) West Side Ambulatory 
Surgery Center. 
5.0 STUDY POPULATION 
5.1 
Number of Subjects 
192 
5.2 
Inclusion Criteria 
Subjects of either gender will be included if they: 
• 
Ambulatory arthroscopic unilateral anterior cruciate ligament repair surgery with bone tendon 
bone autograft 
• 
English-speaking 
• 
ASA I-III 
• 
BMI < 35 
 
5.3 
Exclusion Criteria 
Subjects will be excluded from the study if they: 
• 
History of chronic pain syndromes 
• 
Chronic opioid use (daily morphine milligram equivalents > 30 mg for at least 3 months) 

 
Protocol Number: 2022-1962  
Version Date: 11/25/2024 
 
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• 
Contraindication to peripheral nerve blocks 
• 
Contraindication to neuraxial anesthesia 
• 
History of peripheral neuropathy or pre-existing neurological deficits 
• 
Psychiatric or cognitive disorder that prohibit patient from following study protocol 
• 
Allergy to local anesthetic or study medications 
• 
Multiligament surgery 
• 
History of substance abuse 
• 
Infection at site of injection 
• 
diagnoses of Type I or Type II diabetes 
5.4 
Randomization 
Participants will be assigned at random to one of 2 study groups: 
o 
Group 1 (control): patients receive adductor canal block (ACB) + infiltration between 
the popliteal artery and capsule of the posterior knee (IPACK)  
o 
Group 2 (genicular nerve block): patient receive ACB + IPACK + GEN 
6.0 PROCEDURES 
6.1 
Surgical Procedure 
Arthroscopic anterior cruciate ligament repair 
6.2 
 Medical Record Requirements 
 
Using EPIC, research staff will review the patient's medical history to determine eligibility to 
participate in the study. 
 
PHI that will be reviewed: 
 
Name, DOB, preferred language, medical history, allergies, current outpatient medication, 
weight & body mass index 
 
6.3 
Data Collection 
 
The following data will be collected: 
 
Pre-operative/Baseline 
Name, MRN, DOB, Race, Ethnicity, Gender, Height, Weight, BMI, ASA class, phone number, 
co-morbidities  
 
Surgical procedure 
• 
Surgery details (date of surgery, surgeon, laterality, duration, tourniquet use) 
• 
Anesthesia details (neuraxial, PNB, medications given) 
 
Follow-up visits (PACU, Post-operative day of surgery (POD) 1, 2, 3, 4, 7) 
• 
Brief Pain Inventory (BPI) 
• 
Analgesic duration 
• 
ACB assessment 
• 
Opioid consumption 

 
Protocol Number: 2022-1962  
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• 
NRS pain score 
• 
Patient satisfaction 
7.0 STATISTICAL ANALYSIS 
Proposed analysis (e.g., student’s t-test, ANOVA, chi-square, regression, etc.): two-sample 
t-test (one sided- alternative hypothesis OME reduction 0-24 hours mean (gen block) < mean 
(control) 
Interim analysis planned?: No 
Alpha level:  0.05 
Beta or power level:  0.8 
Primary outcome variable estimate (mean +/- s.d. for continuous outcome, 
frequency/percentage for categorical variable): 28.2 +/- 23.34 
Number of groups being compared (use 1 for paired analysis within the same subjects):  2 
Effect size or change expected between groups:  33% reduction in opioid consumptions 0-24 
hours after block time (9.31) 
Resulting number per group: 96 
Total sample size required: 192 (10% attrition added to 174 needed for stat. significance) 
 
8.0 ADVERSE EVENT ASSESSMENT 
All Adverse Events (AEs) will be reported in the final study report. 
 
9.0 REFERENCES 
1. Aaron Conger, DO, et al. Genicular Nerve Radiofrequency Ablation for the Treatment of 
Painful Knee Osteoarthritis: Current Evidence and Future Directions, Pain Medicine, Volume 
22, Issue Supplement_1, July 2021, Pages S20–S23 
2. Rambhia M, et al. Ultrasound-guided genicular nerve blocks following total knee arthroplasty: 
a randomized, double-blind, placebo-controlled trial. Reg Anesth Pain Med. 2021 
Oct;46(10):862-866.  
3. Caldwell GL Jr, Selepec MA. Reduced Opioid Use After Surgeon-Administered Genicular 
Nerve Block for Anterior Cruciate Ligament Reconstruction in Adults and Adolescents. HSS 
J. 2019 Feb;15(1):42-50.  
4. Gruskay JA, et al. Surgeon-Administered Anterolateral Geniculate Nerve Block as an Adjunct 
to Regional Anesthetic for Pain Management Following Anterior Cruciate Ligament 
Reconstruction. Arthrosc Tech. 2022 Jan 20;11(1):e1-e6. 
5. Kim DH, et al. Adductor canal block versus femoral nerve block for total knee arthroplasty: a 
prospective, randomized, controlled trial. Anesthesiology. 2014 Mar;120(3):540-50. 
6. Kim DH, et al. Addition of Infiltration Between the Popliteal Artery and the Capsule of the 
Posterior Knee and Adductor Canal Block to Periarticular Injection Enhances Postoperative 
Pain Control in Total Knee Arthroplasty: A Randomized Controlled Trial. Anesth Analg. 2019 
Aug;129(2):526-535.  
7. Kim DH, et al. Superior Trunk Block: A Phrenic-sparing Alternative to the Interscalene Block: 
A Randomized Controlled Trial. Anesthesiology. 2019 Sep;131(3):521-533 
8. Kim DH, et al.  Pericapsular nerve group with lateral femoral cutaneous blocks for hip 
arthroscopy: a retrospective cohort study.  ASRA abstract presentation 2022