A Randomized Controlled Trial to Evaluate a Novel Analgesia Technique for ACL Reconstruction: Adductor Canal Block With an IPACK Versus Adductor Canal Block
Phase: PHASE4
Conditions: Anterior Cruciate Ligament Injury
Sponsor: Hospital for Special Surgery, New York

 
Page 1 of 14 
 
 
 
 
 
 
 
 
A Novel Analgesia technique for ACL 
Reconstruction: Adductor Canal Block with an 
IPACK versus Adductor Canal Block 
FUNDER: 
Department of Anesthesiology 
PROTOCOL NO.: 
2017-0934 
VERSION & DATE: 
7/25/2019 
 
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 
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. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 2 of 14 
 
 
 
 
TABLE OF CONTENTS 
 
TABLE OF CONTENTS ............................................ 2 
PROTOCOL SYNOPSIS ........................................... 3 
1.0 
INTRODUCTION ............................................. 5 
2.0 
OBJECTIVE(S) OF CLINICAL STUDY .......... 7 
3.0 
STUDY HYPOTHESES .................................. 8 
4.0 
STUDY DESIGN ............................................. 8 
4.1 
Endpoints ....................................................................................................................... 8 
4.1.1 
Primary Endpoint ...................................................................................................... 8 
4.1.2 
Secondary Endpoints ................................................................................................ 8 
4.2 
Study Sites ..................................................................................................................... 9 
5.0 
STUDY POPULATION ................................... 9 
5.1 
Number of Subjects ........................................................................................................ 9 
5.2 
Inclusion Criteria............................................................................................................. 9 
5.3 
Exclusion Criteria ........................................................................................................... 9 
6.0 
PROCEDURES ............................................. 10 
6.1 
Intraoperative Protocol ................................................................................................. 10 
6.2 
Data Collection ............................................................................................................. 11 
7.0 
STATISTICAL ANALYSIS ............................ 12 
8.0 
ADVERSE EVENT ASSESSMENT .............. 13 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 3 of 14 
 
 
 
 
 
PROTOCOL SYNOPSIS 
 
Protocol Title: 
A Novel Analgesia technique for ACL Reconstruction: Adductor 
Canal Block with an IPACK versus Adductor Canal Block 
Protocol Number: 
2017-0934 
Protocol Date: 
7/25/2019 
Sponsor: 
Department of Anesthesiology 
Principal Investigator: 
Jonathan Beathe, MD 
Objective: 
A comparison of two pain control methods - the combination of 
Adductor Canal Block (ACB)/Periarticular Injection 
(PAI)/Infiltration of the interspace between the popliteal artery 
and the capsule of the posterior knee (IPACK) versus the 
Periarticular Injection (PAI) - in patients undergoing total knee 
arthroplasty. Primary outcome is NRS pain scores with 
ambulation on postoperative day one (24 hours post-block 
administration). 
Study Design: 
Prospective, randomized controlled, double-blinded study 
Enrollment: 
120 
Subject Criteria: 
 
• 
Patients undergoing BTB ACL reconstruction with 
participating surgeon  
• 
Age 13 or greater  
• 
Planned use of regional anesthesia  
• 
Ability to follow study protocol  
• 
English speaking (secondary outcomes include 
questionnaires validated in English only) 
• 
Patients of participating surgeons: Drs. Allen, Cordasco, 
McCarthy, Nawabi, Pearle, & Williams. 
Data Collection: 
Sources: EPIC, Patient Reported, and Anesthesiologist 
Variables: Name, DOB, Race, Gender, BMI, AUC of NRS Pain 
at rest, NRS with ambulation and with stairs, DVPRS (at rest 
and with movement), opioid consumption, time to meet 
discharge criteria, time to reach DC physical therapy, induction 
time, PONV, nerve block success, block duration, ORSDS, 
patient satisfaction, SF-*, KOOS-Jr, blinding assessment, post-
op neurological symptoms, peroneal palsy (if present), power 
assessment, 2 opioid-related questions, sleep quality and 
duration assessment, bang blinding index 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 4 of 14 
 
 
 
Statistical Analysis: 
• 
Regression based on a generalized estimating equations 
approach 
• 
Alpha level: 0.05 
• 
Beta or power level: 80% 
 
 
 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 5 of 14 
 
 
 
1.0 INTRODUCTION 
 
Patellar autograft ACL reconstruction is a painful surgery that requires optimal pain control 
to ensure expeditious recovery and discharge. Nerve blocks, such as the traditional femoral 
nerve block, are instrumental in effectively providing pain relief and improving patient 
satisfaction1,2. Pain scores are notably decreased with nerve blocks, but motor blockade 
impedes mobility and may pose a fall risk early in the post-operative period3-6. The utilization 
of ultrasound introduces newer block techniques offering adequate analgesia without 
detrimental motor blockade.  
 
The adductor canal block serves as an alternative to femoral nerve blockade in providing 
anterior knee analgesia without significantly compromising quadriceps strength7-10.  Despite 
this advantage, posterior knee compartment pain remains a postoperative concern.  Sciatic 
and posterior tibial nerve blocks are also anesthetic options, but again result in motor 
blockade.  A small percentage of patients receiving sciatic nerve blockade also exhibit foot 
drop due to peroneal nerve injury11. Alternatively, as a sensory block, the periarticular 
injection (PAI) proves to hasten ambulation and recovery after TKA12. The PAI blind injection 
into the posterior capsule seems to aid in pain control of the posterior compartment and 
reduces the total number physical therapy sessions13.  
 
Injection in the interspace between the Popliteal Artery and Capsule of the posterior Knee 
(IPACK) provides an alternative to the PAI blind technique for analgesia in the posterior 
compartment14. The IPACK block is not a nerve block, but rather infiltrates the area between 
the popliteal artery and the femur15. This area is rich with sensory nerve fibers from the 
posterior capsule of the knee, which originate from the sciatic and posterior tibial nerve16.  
There have been several studies validating adductor canal blocks to be noninferior in 
analgesia and superior in quadriceps strength for both TKR (7) and ACL (15) surgeries in 
comparison to the FNB.   There also are retrospective studies validating the use of the 
sciatic nerve block with the femoral nerve block for ACL surgery (16,17,18). There are 
currently no studies published on the use of IPACK with ACB for ACL surgery.  Currently, 
there is an IRB approved prospective study under enrollment at HSS investigating the use of 
the IPACK block for TKR. 
 
In this prospective study, we will be the first to compare pain scores between the two 
groups: ACB/IPACK and ACB in patients undergoing BTB ACL surgery.  We will determine 
whether there is a difference between groups in AUC NRS pain at rest for 24h. 
 
References: 
  
1. Holm B, Kristensen MT, Bencke J, Husted H, Kehlet H, Bandholm T. Loss of knee-
extension strength is related to knee swelling after total knee arthroplasty. Arch Phys 
Med Rehabil . 2010;91:1770–1776. 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 6 of 14 
 
 
 
 
2. Huebner, D, Benthien JP. Efficacy of continuous catheter analgesia of the sciatic 
nerve after total knee arthroplasty. Swiss Med Wkly. 2015;147:w14119. 
3. Ilfeld, BM, Duke, KB, Donohue, MC. The Association between Lower Extremity 
Continuous Peripheral Nerve Blocks and Patient Falls After Knee and Hip 
Arthroplasty. Anesth Analg. 2010: 111(6): 1552-1554. 
 
4. Mizner RL, Petterson SC, Stevens JE, Vandenborne K, Snyder-Mackler L. Early 
quadriceps strength loss after total knee arthroplasty. The contributions of muscle 
atrophy and failure of voluntary muscle activation. J Bone Joint Surg Am . 2005;87: 
1047–1053. 
 
5. Johnson RL, Kopp SL, Hebl JR, Erwin PJ, Mantilla CB. Falls and major orthopedic 
surgery with peripheral nerve blockade: a systematic review and meta-analysis. Br J 
Anaesth . 2013;110:518–528.   
 
6. Muraskin SI, Conrad B, Zheng N, Morey TE, Enneking FK. Falls associated with 
lower-extremity-nerve blocks: a pilot investigation of mechanisms. Reg Anesth Pain 
Med . 2007;32:67–72. 
 
7. Kim DH, Lin Y, Goytizolo EA, Kahn RL, Maalouf DB, Manohar A, Patt ML, Goon AK, 
Lee YY, Ma Y, Yadeau JT. Adductor canal block versus femoral nerve block for total 
knee arthroplasty: a prospective, randomized, controlled trial. Anesthesiology. 2014 
Mar;120(3):540-50. 
 
8. Lund J, Jenstrup MT, Jaeger P, Sorensen AM, Dahl JB. Continuous adductor-canal-
blockade for adjuvant post-operative analgesia after major knee surgery: preliminary 
results. Acta Anaesthesiol Scand . 2011;55:14–19. 
 
9. Jenstrup MT, Jaeger P, Lund J, et al. Effects of adductor-canal-blockade on pain and 
ambulation after total knee arthroplasty: a randomized study. Acta Anaesthesiol 
Scand . 2012;56:357–364. 
 
10. YaDeau JT, Goytizolo EA, Padgett DE, Liu SS, Mayman DJ, Ranawat AS, et al. 
Analgesia after total knee replacement: local infiltration versus epidural combined 
with a femoral nerve blockade: A prospective, 6andomized pragmatic trial. Bone 
Joint J 2013; 95-B: 629–35. 
 
11. Schinsky, MF, Macaulay W, Parks, ML, Kiernan, H, Nercessian, OA. Nerve injury 
after primary total knee arthroplasty. J of Arthroplasty. 2001;16(8):1048-1054. 
 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 7 of 14 
 
 
 
12. Kovalak, E, Dogan, AT, Uzumcugil, O, Obut, A, Yildiz, AS, Kanay, E, Tuzuner, T, 
Ozyuvaci, E. A comparison of continuous femoral nerve block and periarticular local 
infiltration analgesia in the management of early period pain developing after total 
knee arthroplasty. Acta Orthrop Traumatol Turc. 2015;49(3):260-266. 
 
13. Horn, BJ, Cien, A, Reeves, P, Pathak, P, Taunt, CJ. Femoral Nerve Block vs. 
Periarticular bupivacaine Liposome injection after primary total knee arthroplasty: 
effect on patient outcomes. 2015. 115:714-719.  
 
14. Elliott CE, Myers TJ, Soberon JR, et al. The Adductor Canal Block Combined with 
iPACK Improves Physical Therapy Performance and Reduces Hospital Length of 
Stay (Abstract 197). Presented at the 40th Annual Regional Anesthesiology and 
Acute Pain Medicine Meeting (ASRA), May 14-16, 2015, in Las Vegas, Nevada. 
 
15. NYSORA – The New York School of Regional Anesthesia: NYSORA Webcast 
Series: Innovative Regional Techniques for Analgesia After Total Knee Arthroplasty 
 
16. Horner G., Dellon AL. Innervation of the human knee joint and implications for 
surgery. Clin Orthop Relat Res . 1994;301:221–226. 
 
17. Abdullah Anesthesiology 2016 Vol 124 No5, p 1053-64 
 
18. Harbell, Cohen JCA Sept 2016, Vol. 33:68-74 
 
19. Cohen J Anesth Clin Res 2014, Vol 5. 1-5 
 
20. Jansen AANA Journal June 2009 Vol 77, No.3  
 
21. Williams Anesthesiology. 2003 May; 98(5): 1206-13 
 
22. Kim IRB #2016-0168 Approved 3/17 
2.0 OBJECTIVE(S) OF CLINICAL STUDY 
 
Adductor canal blocks have been shown to effectively provide adequate analgesia without 
compromising quadriceps strength. IPACK has been shown to optimize pain relief by 
providing analgesia to the posterior compartment of the knee without compromising foot 
strength. The IPACK is also known as the SPANK block (sensory posterior articular nerves 
of the knee) and is shown to involve blocking the superior medial and lateral genicular 
nerves, providing analgesia to the capsule of the knee joint as well as the intraarticular and 
extra-articular ligaments.  By utilizing these new techniques, it may be possible to optimize 
pain relief without compromising motor strength. This may facilitate ambulation threshold 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 8 of 14 
 
 
 
and reduce opioid consumption (with its associated adverse effects), possibly leading to an 
earlier discharge. The reason to do this study is to investigate whether the ACB/IPACK 
(anterior/posterior) in combination would be a better alternative to ACB alone.  Furthermore, 
the study will also determine whether ACB/IPACK is superior to ACB in lowering pain scores 
at 24 hours post block administration. The study will assess the analgesic component of this 
intervention, however the DVPRS complete assessment is a 5-item instrument that includes 
the biopsychosocial impact of pain.  We hypothesize that superior analgesia early in 
recovery may contribute to an improvement in DVPRS and functional outcomes (KOS) well 
after block resolution.  In addition, questions related to opioid consumption may direct future 
studies in exploring strategies to reduce the risks associated with narcotic analgesics. 
The aim of this study is to determine will the IPACK group will have lower pain scores. 
3.0 STUDY HYPOTHESES 
This is a prospective study to assess whether Patellar-autograft ACL reconstruction patients 
who receive ACB + IPACK will have reduced NRS pain in the first 24 hours postoperatively 
compared to ACB alone. 
4.0 STUDY DESIGN 
4.1 
Endpoints 
4.1.1 
Primary Endpoint 
1. Average NRS pain difference at rest during the first 24 hours postoperatively 
(starting at 3 hours post spinal placement): every 30 min for 3 hours, then 6, 12, 18, 
and 24 hours. 
 
4.1.2 
Secondary Endpoints 
1. Time to meet discharge criteria: modified post anesthetic discharge scoring system 
2. Time to ambulate 
3. Induction time (time out to induction end) 
4. PONV (PACU discharge) 
5. ORSDS (POD1, POD14) 
6. Block duration (measured as time of block placement to when patient reports block 
wearing off via phone call) (POD1, POD2) 
7. Opioid consumption (POD0, POD1, POD2, POD3, POD7)  
8. Continued opioid consumption as yes/no (POD14) 
9. NRS pain score with ambulation and with stairs (PACU) 
10. DVPRS pain score at rest (pre-op, PACU discharge, POD1, POD2, POD7 and 6wks) 
11. SF-8 (pre-op, POD7, and 6 wks) 
12. KOOS-Jr assessment (pre-op and 6 wks) 
13. Patient satisfaction with pain control (PACU discharge, POD1, POD2) 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 9 of 14 
 
 
 
14. Incidence and duration of postoperative neurologic symptoms detected including 
numbness, paresthesia, weakness (POD7) 
15. Incidence and duration of transient peroneal palsy,  if present (POD0, POD1, POD2) 
16. Power assessment of extension of operative limb (quad strength) and dorsiflexion at 
ankle (peroneal weakness) using dynamometer (pre-op, PACU discharge) 
17. Response to the following 2 questions: Are you concerned about running out of your 
prescription pain medication? (yes/no) Are you concerned about being addicted to 
prescription pain medication? (yes/no) (POD 7, POD14) 
18. Sleep quality assessment and duration of sleep using actimeter (POD1) 
19. Bang Blinding Index (POD7) 
 
4.2 
Study Sites 
This study will take place at the main campus of the Hospital for Special Surgery (HSS). 
5.0 STUDY POPULATION 
5.1 
Number of Subjects 
120 
 
5.2 
Inclusion Criteria 
Subjects of either gender will be included if: 
• 
Patients undergoing BTB ACL reconstruction with participating surgeon  
• 
Age 13 or greater  
• 
Planned use of regional anesthesia  
• 
Ability to follow study protocol  
• 
English speaking (secondary outcomes include questionnaires validated in English 
only) 
• 
Patients of participating surgeons: Drs. Allen, Cordasco, McCarthy, Nawabi, Pearle, 
Williams. 
5.3 
Exclusion Criteria 
Subjects will be excluded from the study if: 
• 
Hepatic or renal  insufficiency  
• 
Younger than 13 years old 
• 
Patients undergoing general anesthesia 
• 
Allergy or intolerance to one of the study medications  
• 
BMI > 40 
• 
Diabetes 
• 
ASA IV 
• 
Chronic gabapentin/pregabalin use (regular use for longer than 3 months) 
• 
Chronic opioid use (taking opioids for longer than 3 months, or daily morphine 
equivalent of >5mg/day for one month) 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 10 of 14 
 
 
 
6.0 PROCEDURES 
6.1 
Intraoperative Protocol 
 
Both groups will receive intraoperative intravenous sedation with midazolam and propofol. 
Patients will not be given ketamine during the operation.  Patients will be given IV 4mg 
dexamethasone, 4mg ondansetron, 20mg famotidine, and up to 100mcg fentanyl.  Upon 
skin closure, patients will receive IV toradol 30mg (15mg for 65 or older). 
 
A spinal anesthetic with 1.5% mepivacaine (3.5cc) will be performed for all groups. 
 
Surgeons are not to administer any additional local anesthetic infiltration at the surgical site. 
 
Group 1- IPACK with ACB group  
Adductor canal block technique; supine position, after IV sedation.  Ultrasound guided with 
linear transducer, GE or sonosite,  Chiba needle, 22G/4 inch.  Identify the femoral artery in 
the adductor canal deep to the Sartorius muscle, below the vasoadductor membrane. Mid-
thigh injection of 15 cc of bupivacaine 0.5% with 2 mg of preservative-free dexamethasone. 
The local anesthetic will be delivered periarterially with spread anterior to the femoral artery, 
encompassing 9 o’clock to 3 o’clock position of the artery, surrounding the saphenous 
nerve.  
 
IPACK technique:  prone or supine, frog-leg position.  Ultrasound guided with c60 sonosite 
probe (5-2 Hz).  22G/4 inch Chiba needle.   Identify the popliteal artery at popliteal crease; 
move cephalad, just beyond the femoral condyles, at the confluence with the femur. Identify 
space between the femur and popliteal artery.  From medial to lateral, place needle in 
between the popliteal artery and femur with the tip ending 2-3 cm lateral to the artery.  Inject 
25 cc of 0.25% bupivacaine with 2 mg of preservative-free dexamethasone, infiltrating the 
area between the artery and femur.    
 
Group 2 – ACB group  
 
ACB (same method as above).  
 
Postoperative: 
 
Postoperative analgesia will consist of: 
 
Acetaminophen (1 g  IV upon arrival to PACU)  
Ketorolac (30 mg IV 6 hrs following intraop dose if not yet discharged, 15 mg for 65 or older)  
Tramadol (50mg q6hrs PRN mild pain 1-3) 
Tramadol (100mg q6hrs PRN moderate pain 4-6) 
Oxycodone (5 mg q3hrs PRN severe pain 7-10) 
 
Dilaudid IV rescue will only be ordered for severe 7-10 pain refractory to oxycodone. 
 
Dexamethasone (4mg IV push PRN nausea) 
Ondansetron (4mg IV q 8 hr PRN nausea) 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 11 of 14 
 
 
 
Metoclopramide (10mg IV q 6 hr PRN vomiting) 
Scopolamine patch (prn refractory nausea) 
 
Home regimen will be Naproxen 500mg q12 and Percocet 5/325mg 1-2 tabs q4hr prn pain, 
dispense #30 
 
Physical Therapy 
one session on DOS. 
6.2 
Data Collection 
The following data will be collected: 
 
Pre-operative/Baseline 
• 
Consent 
• 
NRS Pain (at rest) 
• 
DVPRS Pain 
• 
SF-8 
• 
KOOS-Jr 
• 
Power assessment 
 
Post-Operative Day 0 (POD 0) 
• 
NRS pain scores at rest 
• 
NRS pain (with ambulation and with stairs) 
• 
Time to meet discharge criteria 
• 
Time to ambulation 
• 
Induction time 
• 
PONV 
• 
DVPRS Pain 
• 
Physical therapy 
• 
Patient satisfaction 
• 
Opioid consumption 
• 
Post-op peroneal palsy (if present) 
• 
Power assessment 
 
Post-Operative Day 1 (POD 1) 
• 
ORSDS 
• 
Block Duration 
• 
DVPRS Pain 
• 
Blinding assessment 
• 
Patient satisfaction 
• 
Opioid consumption 
• 
Post-op peroneal palsy (if present) 
• 
Sleep quality and duration assessment 
 
Post-Operative Day 2 (POD 2) 
• 
Block duration 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 12 of 14 
 
 
 
• 
DVPRS Pain 
• 
Patient satisfaction 
• 
Opioid consumption 
• 
Post-op peroneal palsy (if present) 
 
Post-Operative Day 3 (POD 3) 
• 
Opioid consumption 
 
Post-Operative Day 7 (POD 7) 
• 
DVPRS Pain 
• 
2 Opioid-related questions 
• 
SF-8 
• 
Opioid consumption 
• 
Postop neurologic symptoms 
• 
Bang blinding index 
 
Post-Operative Day 14 (POD 14) 
• 
ORSDS 
• 
2 opioid-related questions 
• 
Opioid consumption 
 
6 Weeks Post-Operative 
• 
DVPRS Pain 
• 
SF-8 
• 
KOOS-Jr 
7.0 STATISTICAL ANALYSIS 
1. Proposed analysis (e.g., student’s t-test, ANOVA, chi-square, regression, etc.):  
Regression based on a generalized estimating equations approach 
2. Alpha level:   0.05 
3. Beta or power level: 80% 
4. Primary outcome variable estimate (mean +/- s.d. for continuous outcome, 
frequency/percentage for categorical variable): Within-group standard deviation of 
NRS pain at rest = 4.1 points (based on Abdallah et al, 2016 [1]) 
5. Number of groups being compared (use 1 for paired analysis within the same 
subjects):  2 
6. Effect size or change expected between groups:  2 points is considered a clinically 
significant difference in pain scores in previous literature [1,2,3]) 
7. Resulting number per group: 47 
8. Total sample size required: 120 (original: 100, use120 total to account for 20% 
attrition/withdrawal) 
 
Primary outcome: 
The primary outcome, NRS pain at rest during the first 24 hours postoperatively, will be 
compared between the ACB and ACB + IPACK groups regression based on a generalized 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 13 of 14 
 
 
 
estimating equations approach. The observed difference between the ACB and ACB + 
IPACK groups will also be compared to the previously defined clinically meaningful 
difference in NRS pain for the first 24 postoperative hours. 
 
Secondary outcome: 
The secondary outcomes will also be compared between the ACB and ACB + IPACK 
groups. Specific statistical approaches will be determined by the observed distribution of 
these outcomes: 
• 
As a sensitivity analysis, AUC of NRS pain at rest during the first 24 hours 
postoperatively (calculated using the trapezoidal rule [similar to Abdallah et al. 2016 
[1]) will be compared between groups using the Mann-Whitney-Wilcoxon U test or 
two-sample t-test (depending upon the distribution of the data). 
• 
Continuous and categorical outcomes measured at multiple time points (e.g., opioid 
consumption, DVPRS score at rest, SF-8 and KOS assessment, patient satisfaction 
with pain control, etc.) will be analyzed using a generalized estimating equations 
(GEE) approach. 
• 
Categorical outcomes measured at one time point (e.g., continued opioid 
consumption at 2 weeks, etc.) will be analyzed using chi-square and/or Fisher’s 
exact tests. 
• 
Continuous outcomes measured at one time point (e.g., time to meet discharge 
criteria, time to PT clearance, induction time, block duration, incidence and duration 
of transient peroneal palsy, etc.) will be analyzed using Mann-Whitney-Wilcoxon U 
test or two-sample t-tests. 
 
Baseline characteristics: 
Demographics and other baseline characteristics (e.g., age, sex, etc.) will be compared 
between the ACB and ACB + IPACK groups. Balance diagnostics may be used to determine 
similarity of baseline covariates between the two study groups, such as described in Austin 
2009 [2]. 
 
References for Data Analysis section: 
[1] Abdallah, Faraj W., et al. "Adductor canal block provides noninferior analgesia 
and superior quadriceps strength compared with femoral nerve block in anterior 
cruciate ligament reconstruction." The Journal of the American Society of 
Anesthesiologists 124.5 (2016): 1053-1064. 
[2] Austin, Peter C. "Balance diagnostics for comparing the distribution of baseline 
covariates between treatment groups in propensity‐score matched samples." 
Statistics in medicine 28.25 (2009): 3083-3107. 
 
8.0 ADVERSE EVENT ASSESSMENT 
All Adverse Events (AEs) will be reported in the final study report.  
 

 
Protocol Number: 2017-0934  
Version Date:   
 
 
Page 14 of 14