Is Pericapsular Nerve Group (PENG) Block Superior to Interscalene Nerve Block Regarding Motor Power Affection in Shoulder Scope Surgeries? A Randomised Comparative Study.
Phase: NA
Conditions: Shoulder Arthroscopic Surgery
Sponsor: Sherin Refaat

 
Is Pericapsular nerve group (PENG) block superior to 
interscalene nerve block regarding motor power 
affection in shoulder scope surgeries? A randomised 
comparative study. 
 
 
 
 
 
 
 
 
1 March 2025 
 
 
 
 
 
 

 
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Table of Contents 
Title Page 
2 
Study Title 
2 
Investigators 
2 
Introduction: 
3 
Aim of the work 
3 
Objectives: 
3 
Hypothesis 
4 
Ethical Considerations 
4 
Methodology 
5 
I. 
Study design 
5 
II. Study setting and location 
5 
III. 
Study population 
5 
IV. 
Eligibility Criteria 
5 
1. Inclusion criteria 
5 
2. Exclusion criteria 
5 
V. Study Procedures 
6 
1. Randomization 
6 
2. Study Protocol 
6 
3. Measurement tools 
6 
 

 
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VI. 
Study outcomes 
7 
1. Primary outcome 
7 
2. Secondary outcome(s) 
7 
Statistical Analysis 
7 
I. 
Sample size 
7 
II. Statistical analysis 
7 
References 
8 
 
 

 
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Title Page 
Study Title 
  
Is Pericapsular nerve group (PENG) block superior to interscalene nerve block 
regarding motor power affection in shoulder scope surgeries? A randomised 
comparative study. 
Investigators 
Candidate Details 
Name: Bassem Raafat Kamal Mansour 
Degree: MD 
Affiliation: Assistant Lecturer of anaesthesiology, surgical ICU and pain 
management 
Phone: 01222722475 
E-mail: bassem.k.mansour@gmail.com 
Principle Investigator 
Name and Affiliation: Prof. Dr. Dina Zakaria Mohammed, Professor of 
anaesthesiology, surgical ICU and pain management 
Phone: 01110577774 
E-mail: dinazakaria005@yahoo.com 
Co-investigator (A): 
Name & Affiliation: Dr. Sherine Refaat Mahmoud, Assistant Professor of 
anaesthesiology, surgical ICU and pain management 

 
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Phone: 01005607829 
E-mail: sherin.refaat@hotmail.com 
Co-investigator (B): 
Name & Affiliation: Dr. Alaa Mahmoud Bahaa El Din, Lecturer of 
anaesthesiology, surgical ICU and pain management 
Phone: 01276143115 
E-mail: alaa.taha@kasralainy.edu.eg 
Co-investigator (C): 
Name & Affiliation: Dr. Mohammed Abdel Moneim Morsi, Lecturer of 
anaesthesiology, surgical ICU and pain management 
Phone: 01015651909 
E-mail: dr.mmorsy13@gmail.com 
Introduction: 
Advances in arthroscopic techniques have led to more reliance on shoulder 
arthroscope for several surgeries instead of using more conventional open 
techniques (1). Shoulder scope is used either for diagnostic procedures or 
interventional ones; most commonly rotator cuff muscles repair, labrum repair or 
repair for recurrent shoulder dislocation (2).  
 
As shoulder scope procedures are usually done as day case surgeries, 
patients are often concerned about postoperative pain which is usually more 
intense during the first few hours after the procedure and mainly due to stretch of 

 
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the capsule by irrigation in addition to the manipulation of intracapsular structures 
(3,4). It has been established that multimodal analgesia yields best pain control as 
different pain pathways are targeted with different drugs and techniques with 
regional anesthesia being one of the most prominent modalities (5). For a long time 
interscalene block (ISB) has been used for shoulder scope surgeries. Although it is 
an effective block, the procedure is not devoid of complications which include 
phrenic nerve affection and diaphragmatic paralysis which could affect respiration. 
Also, dural spread and brachial plexus injury are among the recorded complications 
(6,7). Even when these complications do not occur, interscalene block affects 
motor power of the arm while PENG block spares motor power affection which is 
a key factor regarding that shoulder scopes are usually day case surgeries. 
Interscalene block produces an intense motor block of the upper limb 
muscles which may extend to the hand muscles leading to the discomfort of 
patients and predisposing them to injuries (8), patients are always advised to carry 
the numb limb in an immobilizer and to protect it till complete sensory and motor 
function returns. 
 
Therefore, alternatives for interscalene block as suprascapular nerve 
blocks or supraclavicular nerve blocks are being researched. Pericapsular nerve 
group (PENG) block is one of the novel techniques that are being studied currently, 
its main advantage over interscalene is that the target is the peripheral nerve 
endings around the joint capsule rather than tackling large nerves as the brachial 
plexus trunks (9). It has been first introduced in hip arthroplasty and other hip 
surgeries and showed promising results; thus, it is being applied to shoulder scope 
surgeries (10).  

 
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Papers have been published investigating the efficacy of PENG block in hip 
surgery with different control and comparison groups, as was done by Mosaffa F et 
al when comparing PENG with fascia iliaca compartment block (11). Other studies 
were done on PENG block efficacy in shoulder surgery, but with comparison against 
suprascapular nerve block, and with the main focus on postoperative pain relief as 
a primary outcome rather than recovery of motor power.  To our knowledge, this 
is the first study to compare between the effect of PENG block and interscalene 
block on muscle power of the hand in shoulder arthroscopic surgery.  
Aim of the work 
The aim of the study is to compare the effect of PENG block and 
interscalene block on the motor power of the hand and time to full recovery of 
motor affection if any. 
Objectives: 
● To assess effectiveness of PENG block in recovery of hand motor power 
compared with ISB  
● To compare between PENG and ISB in controlling postoperative pain 
● To assess effectiveness of PENG block in reducing postoperative opioid 
consumption compared with ISB 

 
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Hypothesis 
We hypothesize that PENG block will be superior to interscalene nerve 
block regarding motor power sparing. 
Ethical Considerations 
This study will be conducted after taking approval of the research ethical 
committee. Written informed consent will be obtained from study participants or 
their legally authorized representative.  

 
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Methodology 
I. 
Study design 
Randomised comparative single blinded superiority study. 
II. 
Study setting and location 
This study will be conducted at the theatre for orthopedic surgeries at 
The Cairo University Teaching Hospital. 
III. 
Study population 
Patients scheduled for arthroscopic shoulder surgery 
IV. 
Eligibility Criteria  
1. Inclusion criteria 
● Adult patients (age 22-60) scheduled for arthroscopic shoulder surgery 
under general anesthesia 
● Both genders 
● ASA grade I-II 
● BMI less than 35 
● Duration of surgery 90-120 minutes 
2. Exclusion criteria 
● ASA grade III-IV 
● Allergy to local anesthetics 
● Coagulation disorder (INR >1.2, Platelets <100,000), or recent intake 
of clopidogrel or warfarin within 1 week. 
● Active infection at site of injection 

 
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V. 
Study Procedures 
1. Randomisation 
This is a single centre randomised comparative trial. Patients 
undergoing arthroscopic shoulder surgery will be randomised to receive 
either PENG block, which is the intervention group, or to receive 
interscalene block. 
Randomisation will be done via computer generated random 
numbers which will be enclosed in envelopes with 60 envelopes in total, 30 
for each group. This is a single blinded study so an anesthesiologist who will 
not partake in this study will open the envelopes and proceed with the 
allocated block. After the procedure, the anesthesiologist who will assess 
motor power recovery and collect postoperative data will also be blinded to 
the type of block given. Therefore, to reduce bias only the anesthesiologist 
and main researchers will be aware of the allocation, while the outcome 
data collector will be blinded. 
2. Study Protocol 
Patients in this study will be randomly assigned to one of two groups; 
Group A will receive PENG block and Group B will receive interscalene block. 
All patients will be evaluated preoperatively by routine lab investigations (full 
blood picture, serum electrolytes, liver and kidney function tests and 
coagulation profile).  
Patients will be educated concerning the nature of the procedure and 
its possible complications, and all patients will sign a written informed 
consent. Short term fasting will be encouraged (6 hours for solid food, 2 
hours for clear fluids). A 3rd generation cephalosporin will be given 30 min 
prior to the procedure as prophylaxis. Before admittance to the operation 

 
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theatre, a 22G cannula will be inserted and anxiolysis will be achieved by 
giving the patients midazolam 2 mg IV. 
Upon arrival to the operation room, all patients will receive standard 
monitoring (Pulse oximeter, ECG, NIBP, Capnography), and baseline 
hemodynamic measurements of heart rate, systolic blood pressure (SBP), 
diastolic blood pressure (DBP) and mean arterial blood pressure (MAP) will 
be recorded. Also baseline muscle power of the hand on the same side of 
surgery will be measured using a digital dynamometer (Handeful Digital 
Hand Dynamometer, Handeful, CA, United States). The dynamometer we are 
using is a digital one that measures grip strength in kilograms. 
Group P (PENG Block group): 
Patients in this group will receive PENG block prior to induction of 
general anesthesia. Patient will be placed in supine position with arm 
abducted and externally rotated. Skin will be disinfected then under 
ultrasonic guidance (ACUSON X300™ ultrasound system, Siemens Medical 
Solutions, Inc, Germany) a high frequency linear ultrasound probe (12MHz) 
will be applied longitudinally between the head of humerus and coracoid 
process then local infiltration will be done using 29 G needle to apply 3 mL 
lidocaine 2%. After identification of deltoid muscle and subscapularis muscle 
tendon which should be immediately superficial to humeral head, a 22-gauge 
needle (SonoPlex® STIM, PAJUNK® Medical System L.P., Germany) will be 
advanced to pierce the deltoid and target the tip to be just touching the 
subscapularis tendon. A test dose of 3 ml saline solution will be injected to 
visualise the separation of deltoid from subscapularis and confirm and the 

 
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needle is in the correct position. Afterwards 15 ml of 0.25% bupivacaine will 
be injected to complete the block. A wait time of 30 minutes will be allowed 
before induction of general anesthesia to ensure the full activation of the 
block. 
Group I (Interscalene block): 
Patients in this group will also receive ISB prior to general anesthesia. 
With patient placed in supine position and head facing away from the side 
being blocked, the skin is disinfected first then the linear ultrasound probe is 
placed transversely on the neck to identify the carotid artery. Then the 
transducer is moved slightly laterally until middle and anterior scalene 
muscles are identified with the brachial plexus between them then local 
infiltration will be done using 29 G needle to apply 3 mL lidocaine 2%. A 22-
gauge needle will be introduced in plane in a lateral-medial direction aiming 
towards the space between the roots. After a 3 ml saline injection for 
confirmation of proper position, 15 ml of 0.25% bupivacaine will be injected 
with advancement of the needle as the roots are displaced by the injectate. 
Adequate injection will be confirmed by visualizing the roots being 
surrounded by the local anesthesia infiltrate. 
Patients receiving either block will wait 30 minutes before induction 
of general anesthesia. Interscalene block will be tested using pin prick test 
on shoulder and upper arm area, by loss of shoulder abduction, and finally 
by passively moving the arm to check for loss of previously present pain on 
movement. PENG block will be tested using pin prick test and loss of pain on 
passive movement as well. A block not fulfilling these examinations will be 

 
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deemed unsuccessful, and the patients will be given additional opioids in the 
form of morphine 5 mg IV with induction of general anesthesia. These 
patients will be excluded from the study. Before induction of general 
anesthesia another dynamometer measurement will be recorded. 
In both groups patients will receive general anaesthesia using the 
standard centre preferences; IV induction via propofol 2 mg/kg and fentanyl 
1 mic/kg for induction, then atracurium 0.5 mg/kg for intubation followed by 
0.1 mg/kg every 20 minutes for maintenance. An additional dose of fentanyl 
1 mic/kg will be administered on skin incision. 
For maintenance of anaesthesia, isoflurane will be administered at a 
concentration of 1.2-2%, and the patient will be mechanically ventilated 
using parameters that will achieve normal end-tidal CO2 (35-45 mmHg) and 
oxygen saturation (> 95%). To maintain relaxation atracurium will be given 
as 0.1 mg/kg every 20 minutes. 
Intraoperative hemodynamics will be measured at 10 min intervals, 
both heart rate and blood pressure values (SBP, DBP and MAP) will be 
recorded. Bradycardia defined as heart rate below 60 beats per minute, and 
bradycardia will be managed if heart rate drops below 55 bpm by giving 
atropine 0.04 mg/kg IV bolus to be repeated after 5 minutes if needed. 
Hypotension also described as SBP below 90 mmHg will be managed by 
giving ephedrine 5-10 mg IV bolus. 
At the end of surgery, patients will be given 1 g acetaminophen IV, and 
NSAID will be given in the recovery room in the form of ketorolac 30 mg IV. 

 
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For recovery, neuromuscular blockade will be reversed using 
neostigmine 0.04 mg/kg and atropine 0.02 mg/kg, and the patient will be 
extubated fully awake and when adequately reversed which is clinically 
assessed as the patient achieves tidal volumes > 5ml/kg. 
Patients will be transferred to the post anesthesia care unit (PACU), 
and same intraoperative hemodynamics will be measured every 10 min 
through their PACU stay duration. With regards to postoperative 
management, Visual analog scale (VAS), which is a scale from 0 to 10 where 
0 represents no pain at all and 10 represents the most severe pain, will be 
used to assess pain. VAS assessment will be carried out during the 1st hour at 
the PACU then at 2, 4, 6, 12, and 24 hours postoperative during day 1, and If 
VAS is >4, opioids will be administered in the form nalbuphine 5mg IV, and 
the time to first dose and total number of doses given will be noted not to 
exceed 60 mg per day. Also, hand grip power will be assessed at the PACU 
then at 2, 4, 6, 12, and 24 hours postoperatively, and this will be done using 
the digital dynamometer. The readings will be compared with a 
measurement of the patient’s baseline grip power of the same hand taken 
before surgery and with readings taken after block administration. 
3. Measurement tools 
● Hand grip power will be measured using digital dynamometer at 
these intervals: immediately postoperative at PACU and then at 2, 4, 
6, 12, and 24 hours postoperative, and results compared with 
baseline measurement. 
● Time for full recovery of hand grip power. 

 
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● Intraoperative hemodynamics in the form of heart rate and mean 
blood pressure every 10 minutes. 
● Postoperative pain will be measured using VAS score at theses 
intervals: immediately postoperative at PACU and then at 2, 4, 6, 12, 
and 24 hours postoperative. 
● Postoperative hemodynamics in the form of heart rate and mean 
blood pressure in PACU every 10 minutes until discharge  
● Time to first opioid dose 
● Total amount of opioid administered. 
● Patient satisfaction will be measured at 24 hours postoperative using 
self reported satisfaction scale (1= very dissatisfied and 5=very 
satisfied) 
VI. 
Study outcomes 
1. Primary outcome 
●  Time for full recovery of hand power, defined as time from start of 
block activation till time of achieving grip strength similar to patient’s 
baseline 
2. Secondary outcome(s) 
● Hand grip power after surgery at PACU, then at 2, 4, 6, 12, and 24 
hours. 
● Time to first analgesia request 
● VAS score after surgery at rest and during movement at PACU then at 
2, 4, 6, 12, and 24 hours 

 
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● Patient satisfaction score at 24 hours postoperative 
● Intraoperative hemodynamics 
Statistical Analysis 
I. 
Sample size 
Based on a previous study (12) the duration of motor block in patients 
receiving ISB was 711± 151 min (REF). A minimum sample of 50 patients 
is needed to detect a 20% reduction in duration of motor block. The study 
power was set at 90% and alpha error was set at 0.05. Sample size was 
calculated using the MedCalc Software V14. The number of envelopes will 
be increased to 60 (30 in each group) to compensate for dropouts. 
II. 
Statistical analysis 
Statistical package for social science (SPSS) software, version 26 for 
Microsoft Windows (SPSS inc., Chicago, IL, USA) will be used for data 
analysis. Categorical data will be presented as frequency (%) and will be 
analyzed by the chi square test. Continuous data will be checked for 
normality using the Shapiro-Wilk test and will be presented as mean 
(standard deviation) or median (interquartile range) as appropriate. 
Continuous data will be analyzed using unpaired the t test or the Mann 
Whitney test according to normality of the data. Repeated measures will 
be analyzed using the analysis of variance (ANOVA) for repeated 
measures with post-hoc pairwise comparisons using the Boneferroni 
tests. A P-value less than 0.05 will be considered statistically significant. 

 
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